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Background: This study focused on the aging mechanism and degradation of mechanical and structural features of elastodontic appliances (EA) under artificial and intraoral aging to achieve oral myofunctional therapy with particular removable silicone elastomer devices., Materials and Methods: EAs artificially aged in saliva with different pH values were investigated through cyclic compression testing along with characterization techniques (Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy), and characterization analysis was also performed on clinically retrieved EAs., Results: Artificial aging was found to have minimal effect on the structural properties of EAs, and intraorally aged samples showed perceptible micro-morphology. The Mullins index and peak stress decreased (P<0.01), while the compression set increased with prolonged aging time. Samples in alkaline saliva showed the largest Mullins effect (P<0.05)., Conclusions: The aging mechanism of the elastomer was found to be the crosslinking of main chains and scission of side chains. The presence of OH- enhanced the rupture degree of side bonds. The decline in viscoelastic properties was shown to be more severe with longer service durations., Clinical Relevance: Research on how the salivary environment and pH affect the aging characteristics of EAs is vital for guiding clinical applications and future modifications to extend their clinical lifetime., (© 2024. The Author(s).)

Magnetic soft grippers have attracted intensive interest due to their untethered controllability, rapid response, and biological safety. However, manipulating living objects requires a simultaneous increase in shape adaptability and gripping force, which are typically mutually exclusive. Increasing the magnetic particle content enhances the magnetic strength but also increases the elastic modulus, leading to low adaptability and high impact force. Here, a porous magnetic soft gripper (PMSG) is developed by integrating a porous structure into a magnetic silicone elastomer. The design of porous hard magnetic composite is characterized by high magnetization, low modulus, and rough surface. It offers the PMSG good compliance, high gripping force, and low impact force at fast gripping. The PMSG is capable of performing a variety of tasks, including the fast and gentle grasping of delicate living objects. The study provides insight into the design of novel magnetic grippers and may offer a promising outlook for biomedical or scientific applications in the manipulation of delicate organisms., (© 2024 Wiley‐VCH GmbH.)

A remarkable variety of organisms use metachronal coordination (i.e. numerous neighboring appendages beating sequentially with a fixed phase lag) to swim or pump fluid. This coordination strategy is used by microorganisms to break symmetry at small scales where viscous effects dominate and flow is time-reversible. Some larger organisms use this swimming strategy at intermediate scales, where viscosity and inertia both play important roles. However, the role of individual propulsor kinematics-especially across hydrodynamic scales-is not well-understood, though the details of propulsor motion can be crucial for the efficient generation of flow. To investigate this behavior, we developed a new soft robotic platform using magnetoactive silicone elastomers to mimic the metachronally coordinated propulsors found in swimming organisms. Furthermore, we present a method to passively encode spatially asymmetric beating patterns in our artificial propulsors. We investigated the kinematics and hydrodynamics of three propulsor types, with varying degrees of asymmetry, using Particle Image Velocimetry and high-speed videography. We find that asymmetric beating patterns can move considerably more fluid relative to symmetric beating at the same frequency and phase lag, and that asymmetry can be passively encoded into propulsors via the interplay between elastic and magnetic torques. Our results demonstrate that nuanced differences in propulsor kinematics can substantially impact fluid pumping performance. Our soft robotic platform also provides an avenue to explore metachronal coordination at the meso-scale, which in turn can inform the design of future bioinspired pumping devices and swimming robots., (Creative Commons Attribution license.)

Although deterioration of silicone maxillofacial prostheses is severely accentuated in smoking patients, the phenomenon has not been systematically studied. To address a gap in the literature concerning the stability of maxillofacial prostheses during service, in this contribution, the effect of cigarette smoke on the aspect and physical properties of M511 silicone elastomer was evaluated. The aspect, surface, and overall properties of the silicone material, pigmented or not, were followed by AFM, color measurements, FTIR, water contact angle measurements, TGA-DTG and DSC, hardness and compression stress-strain measurements. The types of the contaminants adsorbed were assessed by XRF, ESI-MS, MALDI-MS, and NMR spectral analyses. Important modifications in color, contact angle, surface roughness, local mechanical properties, and thermal properties were found in the silicone material for maxillofacial prostheses after exposure to cigarettes smoke. The presence of lead, nicotine, and several other organic compounds adsorbed into the silicone material was emphasized. Slight decrease in hardness and increase in Young's modulus was found. The combined data show important impact of cigarette smoke on the silicone physical properties and could indicate chemical transformations by secondary cross-linking. To our knowledge, this is the first study making use of complementary physical methods to assess the effect of cigarette smoke on the aspect and integrity of silicone materials for maxillofacial prostheses., (© 2024 Wiley Periodicals LLC.)

Background: Digitally fabricated dentures may require relining due to continual alveolar ridge resorption. However, studies evaluating the tensile bond strength (TBS) of digitally fabricated dentures bonded to denture liners are lacking. This study aimed to evaluate the TBS of autopolymerized, heat-polymerized, milled, and 3D printed denture base materials bonded to 2 acrylic-based and 2 silicone-based denture liners, both before and after thermocycling. Additionally, the impact of thermocycling on the TBS were also evaluated., Methods: The TBS of 4 different denture base materials (Palapress (PL), Vertex Rapid Simplified (VR), Smile CAM total prosthesis (SC), and NextDent denture 3D+ (ND)) bonded to 2 acrylic-based (GC Soft-Liner (GC) and Tokuyama Rebase II (RB)) and 2 silicone-based (Ufi Gel P (UP) and Sofreliner Tough M (ST)) denture liners were tested. Specimens (n = 8) were divided into non-thermocycling and thermocycling groups. Non-thermocycling specimens were tested after 24-hours water immersion, while thermocycling specimens were underwent 5000 cycle and were immediately tested. Mode of failure was examined under a stereomicroscope. Data were analyzed using 2-way ANOVA and Tukey HSD tests (α = 0.05), and independent samples t test (α = 0.05) for TBS between non-thermocycling and thermocycling groups., Results: For the non-thermocycling groups, within the same denture liner material, no significant differences were found between denture base materials, except the ND + RB group, which had significantly lower TBS. For the thermocycling groups, within the same denture liner material, the TBS in the PL group exhibited the highest and the ND group exhibited the lowest. Within the same denture base material, in both non-thermocycling and thermocycling groups, the TBS in the ST group exhibited the highest; in contrast, that in the GC group exhibited the lowest. No significant differences were observed in TBS between non-thermocycling and thermocycling groups, except for denture base materials bonded to the ST group, SC + UP, and ND + UP groups., Conclusions: Milled denture base can be relined with acrylic-based or silicone-based denture liner. However, cautions should be exercised when relining 3D printed denture base. Thermocycling did not affect TBS between acrylic-based denture liners and denture bases. In contrast, it affected the bond between silicone-based denture liner and denture base., (© 2024. The Author(s).)

Background: Glaucoma is one of the major irreversible blinding eye diseases in the world. Reducing intraocular pressure (IOP) is the primary treatment option, and taking eye drops daily is the common method. However, short drug duration and poor bioavailability of eye drops may lead to unsatisfied therapeutic effects and inadequate patient compliance., Methods: A brimonidine-loaded silicone rubber insert (BRI@SR@PT) was prepared by loading brimonidine into a surface-modified silicone rubber ring, followed by polydopamine/thermoplastic polyurethane coatings. The physical properties, in vitro cytocompatibility and drug release of BRI@SR@PT were investigated. The BRI@SR@PT was administrated in the conjunctival sac of rabbit eyes, and its in vivo drug release, IOP-lowering efficacy and biosafety were assessed., Results: The BRI@SR@PT presented great thermal stability and excellent elasticity. The BRI@SR@PT was able to release BRI sustainably for 28 days with little toxicity in vitro . Compared to BRI eye drops, the BRI@SR@PT effectively lowered IOP for 21 days based on the sustained BRI release with great biosafety when administrated in conjunctival sac of rabbit eyes in a noninvasive fashion., Conclusions: The conjunctival sac insert (BRI@SR@PT), as a promising drug-delivery platform, may provide a sustained IOP-lowering treatment for patients with ocular hypertension or glaucoma, without the need for invasive procedures.

Statement of Problem: Retention is essential for maxillofacial prosthesis. Adhesives are commonly used for retention because of their simplicity, availability, and cost-effectiveness. Studies that have estimated the differences in bond strength between the types of adhesives and the impact of reapplication are sparse., Purpose: The purpose of this observational clinical study was to estimate the peel bond strength and reapplication effects of water-based and silicone-based adhesives at 0, 24, and 48 hours., Material and Methods: A total of 46 participants were enrolled, with 23 participants in each adhesive test group-water-based and silicone-based adhesive. Silicone elastomeric strips were attached to the ventral aspect of the participants' forearm 5 cm away from the radial styloid prominence. The strength of each adhesive group was tested at 0 hours, and its reapplication effects were evaluated at 24 and 48 hours. The peel bond strength was estimated by using a universal testing machine, and the data were recorded in N/m and statistically analyzed by the independent Student t test and Spearman rho correlation coefficient tests (α=.05)., Results: The mean ±standard deviation of peel bond strength at 0 hours for silicone-based adhesive (111.5 ±2.5 N/m) was higher than that for water-based adhesive (99.9 ±3.9 N/m) (P<.001). On reapplication, the silicone-based adhesive had a higher peel bond strength (113.5 ±2.8 N/m) than the water-based adhesive (105.2 ±3.0 N/m) (P<.001). The results were statistically significant between the 2 groups at different time intervals (P=.04)., Conclusions: The mean peel bond strength of the silicone-based adhesive was higher than that of the water-based adhesive. The reapplication of adhesives improved the bond strength in both the groups., (Copyright © 2022 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Blood-contacting catheters play a pivotal role in contemporary medical treatments, particularly in the management of cardiovascular diseases. However, these catheters exhibit inappropriate wettability and lack antimicrobial characteristics, which often lead to catheter-related infections and thrombosis. Therefore, there is an urgent need for blood contact catheters with antimicrobial and anticoagulant properties. In this study, we employed tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) to create a stable hydrophilic coating under mild conditions. Heparin (Hep) and poly(lysine) (PL) were then modified on the TA-APTES coating surface using the layer-by-layer (LBL) technique to create a superhydrophilic TA/APTES/(LBL) 4 coating on silicone rubber (SR) catheters. Leveraging the superhydrophilic nature of this coating, it can be effectively applied to blood-contacting catheters to impart antibacterial, antiprotein adsorption, and anticoagulant properties. Due to Hep's anticoagulant attributes, the activated partial thromboplastin time and thrombin time tests conducted on SR/TA-APTES/(LBL) 4 catheters revealed remarkable extensions of 276 and 103%, respectively, when compared to uncoated commercial SR catheters. Furthermore, the synergistic interaction between PL and TA serves to enhance the resistance of SR/TA-APTES/(LBL) 4 catheters against bacterial adherence, reducing it by up to 99.9% compared to uncoated commercial SR catheters. Remarkably, the SR/TA-APTES/(LBL) 4 catheter exhibits good biocompatibility with human umbilical vein endothelial cells in culture, positioning it as a promising solution to address the current challenges associated with blood-contact catheters.

Statement of Problem: The choice of cleaning method is an important consideration for lengthening the serviceable time of facial prostheses as microbial organisms and biofilms could degrade facial prostheses and cause skin irritation. Whether microwave disinfection is a suitable cleaning method without degradation of the properties of a prosthesis is unclear., Purpose: The purpose of this in vitro study was to measure the color stability of 6 commonly used facial silicone elastomers after microwave disinfection over a simulated 1.5-year period., Material and Methods: Six different facial silicone elastomers: MDX4-4210, MDX4-4210/Type A, M511, A-2186, VST-50, and A-2000 were mixed with intrinsic silicone white opacifier (except for the control group) and subsequently combined with 4 silicone intrinsic pigment color groups: red (R), yellow (Y), burnt sienna (B), and a mixture of R+Y+B (M). The control group was a silicone elastomer without opacifier or pigment. Each of the 30 experimental groups consisted of 5 specimens (N=150). Five specimens were placed in a 250-mL Erlenmeyer flask filled with 160 mL of tap water. Seven flasks were then placed in a 660-W microwave oven. An exposure of 6 minutes was used according to the antimicrobial efficacy of microwave disinfection protocol on facial silicone prostheses with a final water temperature of 60 °C for 18 times (simulating 1.5 years of microwave disinfection with one 6-minute exposure monthly). A spectrophotometer was used to measure reflectance color change values (∆E). Color differences were calculated following CIELab (∆E* ab ) and CIEDE2000 (∆E00) formulae. ∆E* ab and ∆E00 were statistically analyzed by a linear mixed effects model with 3 factors (silicone type, color shade, and time) using the R Statistical software program (α=.05)., Results: Both ∆E* ab and ∆E00 of all silicone elastomers studied were less than the visual perceptibility thresholds (∆E* ab <1.1 and E00<0.7) and were considered clinically acceptable (∆E* ab <3.0 and E00<2.1) after the 1.5-year simulation of microwave disinfection. Yellow and blue pigments had more effect on MDX4-4210 and M511, while red pigment had more effect on MDX4-4210, MDX4-4210/Type A, and M511 (P<.05). Nevertheless, the values were still below the perceptibility threshold (∆E* ab ≤1.0 and E00<0.6)., Conclusions: All 6 facial silicone elastomers maintained clinically acceptable color after 18 months of exposure to microwave disinfection., (Copyright © 2024 Editorial Council for The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Nasal retainers have been utilized to maintain the position of the nose after primary rhinoplasty in cleft lip patients. However, commercial nasal retainers made from silicone are quite expensive. To address this issue, the authors designed an alternative nasal retainer that is affordable, safe, and has similar biomechanical and biocompatibility properties to other commercial nasal retainers. Three types of nasal retainers were tested: our own (Nostriloo), a commercial nasal retainer from Turkey, and another one from Taiwan. There were 3 samples on each group, with a total sample of 9 retainers. Each sample was tested for biomechanical property and biocompatibility. Elasticity modulus, tensile strength, and direct and indirect toxicity were analyzed. Nostriloo had the least durable tensile strength but showed similar elastic modulus (2.76 ± 0.41 MPa) compared with human lower lateral cartilage (2.09 ± 0.81 MPa). On the basis of direct and indirect toxicity tests, Nostriloo is considered nontoxic. Nostriloo can be utilized for small-scale production and use. Further experiment is needed to produce higher-quality nasal retainers., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 by Mutaz B. Habal, MD.)

Purpose: To evaluate the effect of adding tea tree oil to denture liners on Candida albicans and bond strength to the acrylic denture base., Materials and Methods: Disc-shaped specimens were fabricated from silicone-based resilient liner (Tokuyama, Molloplast), acrylic-based hard liner (GC Reline), and acrylic-based soft liner (Visco-gel). Tea tree oil (TTO) was incorporated into the liners at varying concentrations (0% [control], 2%, 5%, 8%). C albicans were counted by viable colony count, and optical density (OD) was measured with a spectrophotometer. The tensile strength to heat polymerized acrylic denture base was measured in a universal testing machine. The compliance of the data to the distribution of normality was evaluated using the Shapiro Wilk test. Two-way ANOVA, Bonferroni correction, and paired sample t test were performed (α = .05)., Results: The addition of TTO into liners provided a significant decrease in the OD values (P < .001). The control groups of the liners presented the highest colony counts, whereas increasing TTO decreased the results (P < .01). According to tensile bond strength test, 8% TTO addition resulted in a significant decrease for Tokuyama (P < .01) and Molloplast liners (P < .05), while 2% TTO resulted in significance for GC Reline (P < .001)., Conclusions: Denture liners containing increasing percentages of TTO presented lower amounts of C albicans colonies and decreased bond strength to the denture bases. When using TTO for its antifungal properties, the amount added should be carefully selected because the tensile bond strength may be affected.

Aim: This study aims to assess the antimicrobial efficacy and impact on color stability of Thymus (T.) vulgaris solution compared to conventional disinfectants on maxillofacial silicones., Materials and Methods: Various solutions were evaluated, including T. vulgaris solutions at 5 and 10%, saline (control), chlorhexidine (4%), and soap water. The substrates were MDX4-4210 silicone elastomers, and the microorganisms tested were Candida (C.) albicans and Staphylococcus (S.) aureus . The viability of microorganisms was determined through an 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) reduction assay, and color stability was measured using a spectrophotometer with X-Rite Europe software. Statistical analysis was performed using the Kruskal-Wallis test, Mann-Whitney U post hoc test, and Wilcoxon Signed Rank test., Results: Soap water demonstrated superior disinfectant action against both microorganisms, while T. vulgaris solutions at 5 and 10% exhibited comparable antimicrobial efficacy. Chlorhexidine and 10% T. vulgaris solution showed minimal color changes in the silicone material. In contrast, soap water and the 5% T. vulgaris solution resulted in clinically unacceptable color alterations., Conclusion: This study underscores the potential of T. vulgaris as an herbal disinfectant for combating microbial biofilms on maxillofacial silicones, particularly at concentrations of 5 and 10%. The importance of maintaining color stability is emphasized, with Chlorhexidine and the 10% T. vulgaris solution demonstrating effective preservation of esthetics. These findings suggest the viability of considering T. vulgaris as an alternative disinfectant in clinical settings for maxillofacial silicone prostheses., Clinical Significance: Maxillofacial silicones are vital in restoring aesthetic features for individuals with facial trauma, congenital deformities, or post-surgical interventions. Yet, biofilm-related infections jeopardize their durability and visual integrity. Clinically, T. vulgaris signifies a potential advance in prosthodontic care, offering valuable insights for improving antimicrobial performance and aesthetic durability in maxillofacial prostheses. How to cite this article: Peter M, Kanathila H, Bembalagi M, et al . An In Vitro Comparative Evaluation of Conventional and Novel Thymus vulgaris Derived Herbal Disinfectant Solutions against Pathogenic Biofilm on Maxillofacial Silicones and Its Impact on Color Stability. J Contemp Dent Pract 2023;24(12):967-973.

The aim of this research was to obtain new polymer composites with a silicone rubber matrix, having favorable mechanical and functional properties. They contained admixtures in the amount of 10% by weight of expanded graphite (EG) or birch bark (BB). Additionally, some composites contained magnetic particles in the form of carbonyl iron in the amount of 20% by weight. The tensile strength, water absorption, frost resistance, surface contact angle, and free surface energy were examined. Microscopic images were taken using the SEM method and the content of some elements in selected microareas was determined using the EDXS method. In the study, a constant magnetic field with magnetic induction B was used, by means of which the properties and structure of polymer composites were modified. Scientific research in the field of polymers is the driving force behind the progress of civilization. Smart materials are able to respond to external stimuli, such as magnetic fields, with significant changes in their properties. The magnetic field affects not only chemical reactions, but also the crystallographic structure and physicochemical properties of the final products. Owing to their unique properties, such materials can be used in the space industry, automotive industry, or electrical engineering.

Rosin is a characteristic natural renewable resource. In view of the unique hydrogenated phenanthrene ring skeleton structure of rosin, it can be designed and synthesized to modify silicone rubber for improving its mechanical properties, thermal stability, and other properties. In this paper, the research progress of silicone rubber modified by rosin and its derivatives is reviewed, including internal or surface modification of room temperature or high temperature vulcanized silicone rubber. The different chemical modifications and polymerization pathways to obtain bio-based silicone rubber ( e.g. rosin-based silicone cross-linking agent, filler compound rosin-based silicone cross-linking agent, rosin-based polymer, and rosin quaternary ammonium salt bifunctional antibacterial coating) are discussed and its research prospect is reviewed. Overall, the present review article will provide a quantitative experimental basis for rosin to produce bio-renewable multifunctional silicone rubber to increase our level of understanding of the behavior of this important class of silicone rubber and other similar bio-based polymers.

Background: Maxillofacial silicones are the most popular and acceptable material for making maxillofacial prostheses, but they are not perfect in every sense. To enhance their effectiveness, more improvements to their properties are required, such as their antimicrobial efficiency. This study assess the antibacterial effect of barium titanate nanoparticles in various percentages against staphylococcus epidermidis biofilm adhesion after addition to maxillofacial silicone. Methods: Barium titanate nanoparticles were added into VST-50 platinum silicone elastomer in four weight percentages (0.25wt%, 0.5wt%, 0.75wt% and 1wt%). 50 specimens were prepared and categorized into five groups; one control group and four experimental groups. All conducted data was statistically analyzed using (one-way ANOVA) analysis of variance, and Games-Howell multiple comparison test (significant level at p < 0.05). Shapiro-Wilk and Levene's tests were used, respectively, to evaluate the normal distribution and homogeneity of the data. Result: One-way ANOVA test revealed a highly significant difference between all groups, and Games-Howell test revealed a highly significant difference between the control group and the four experimental groups. The 0.25wt% and 0.5wt% groups revealed a highly significant difference between them and with the (0.75%wt and 0.1%wt) groups. While the 0.75wt% group revealed a significant difference with 1wt% group. Conclusions: The addition of barium titanate to VST-50 maxillofacial silicone enhanced the antibacterial activity of silicon against Staphylococcus epidermidis , and this activity seems to be concentration dependent. FTIR analysis demonstrated no chemical interaction between the Barium Titanate and the VST-50 maxillofacial silicone elastomer. SEM pictures show that the barium titanate nanopowder was effectively dispersed inside the maxillofacial silicone matrix., Competing Interests: No competing interests were disclosed., (Copyright: © 2023 Kareem YM and Hamad TI.)

Background and Objectives : One's quality of life depends on overall health, and in particular, oral health, which has been and continues to become a public health issue through frequent manifestations in various forms, from simple oral stomatitis (inflammations of the oral cavity) to the complicated oral health pathologies requiring medical interventions and treatments (caries, pulp necrosis and periodontitis). The aim of this study focused on the preparation and evaluation of vitamins (vitamin A, B1 and B6) incorporated into several silicone-based lining materials as a new alternative to therapeutically loaded materials designed as oral cavity lining materials in prosthodontics. Materials and Methods : Silicone-based liners containing vitamins were prepared by mixing them in solution and becoming crosslinked, and then they were characterized using Fourier-transform infrared (FT-IR) spectroscopy to confirm the incorporation of the vitamins into the silicone network; scanning electron microscopy (SEM) to evidence the morphology of the liner materials; dynamic vapor sorption (DVS) to evaluate their internal hydrophobicity, swelling in environments similar to biological fluids and mechanical test to demonstrate tensile strength; MTT to confirm their biocompatibility on normal cell cultures (fibroblast) and mucoadhesivity; and histopathological tests on porcine oral mucosa to highlight their potential utility as soft lining materials with improved efficiency. Results : FT-IR analysis confirmed the structural peculiarities of the prepared lining materials and the successful incorporation of vitamins into the silicone matrix. The surface roughness of the materials was lower than 0.2 μm, while in cross-section, the lining materials showed a compact morphology. It was found that the presence of vitamins induced a decrease in the main mechanical parameters (strength and elongation at break, Young's modulus) and hydrophobicity, which varied from one vitamin to another. A swelling degree higher than 8% was found in PBS 6.8 (artificial saliva) and water. Hydrolytic stability studies in an artificial saliva medium showed the release of low concentrations of silicone and vitamin fragments in the first 24 h, which increased the swelling behavior of the materials, diffusion and solubility of the vitamins. The microscopic images of fibroblast cells incubated with vitamin liners revealed very good biocompatibility. Also, the silicone liners incorporating the vitamins showed good mucoadhesive properties. The appearance of some pathological disorders with autolysis processes was more pronounced in the case of vitamin A liners. Conclusions : The addition of the vitamins was shown to have a beneficial effect that was mainly manifested as increased biocompatibility, hydrolytic stability and mucoadhesiveness with the mucosa of the oral cavity and less of an effect on the mechanical strength. The obtained lining materials showed good resistance in simulated biological media but caused a pronounced autolysis phenomenon, as revealed by histopathological examination, showing that these materials may have broad implications in the treatment of oral diseases.

BACKGROUND We investigated the bond strength, tensile strength, and water absorption properties of 4 widely used chairside silicone long-term denture soft lining materials and compared properties with those of heat-cured silicone material. MATERIAL AND METHODS Four chairside materials (GC Reline Soft, Mucopren Soft, Sofreliner Soft, and Elite Soft Relining) and a heat-cured silicone material (Molloplast B) were investigated. For tensile and shear bond strength and tensile strength, samples were prepared according to the manufacturers' instructions and the testing machine used. For water absorption, IOS 1567 was followed to prepare specimens. Bond strengths were measured using a Lloyd Instruments materials testing machine. Ten specimens for each test were prepared for each soft liner, except for water absorption and solubility tests, for which only 5 specimens were prepared. ANOVA, Bonferroni, and Kruskal-Wallis tests were used to compare values of materials and assess changes over time. RESULTS There was strong evidence of differences in the properties between materials. GC Reline Soft showed comparable tensile bond (1.4±0.6 MPa), shear bond (1.1±0.4 MPa), tensile strength (5.44±0.98), water absorption (0.92±0.2 µg/mm³), and solubility values (0.3±0.2 µg/mm3) to that of Molloplast B (1.4±0.4; 1.6±0.5; 4.53±0.9 MPa, 1.7±0.3, and 1.0±0.3 µg/mm³, respectively). The water solubility of Sofreliner Soft was significantly lower (1.5±0.8 µg/mm³) than that of Molloplast B. CONCLUSIONS There were significant differences between some properties of 4 chairside denture soft lining materials and that of Molloplast B, which had higher shear and tensile bond strength than chairside denture silicone soft lining materials but had the highest water solubility.

Developing coating materials with low cytotoxicity and high antimicrobial activity has been recognized as an effective way to prevent medical device-associated infections. In this study, a maleic anhydride terpolymer (PPTM) is synthesized and covalently attached to silicone rubber (SR) surface. The formed coating can be further cross-linked (SPM) through the self-condensation of pendent siloxane groups of terpolymer. No crack or delamination of SPM was observed after 500 cycles of bending and 7 day immersion in deionized water. The sliding friction force of a catheter was reduced by 50% after coating with SPM. The SPM coating without adding any extra antibacterial reagents can kill 99.99% of Staphylococcus aureus and Escherichia coli and also significantly reduce bacterial coverage, while the coating displayed no antimicrobial activity when maleic anhydride groups of SPM were aminated or hydrolyzed. The results of the repeated disinfection tests showed that the SR coated with SPM could maintain 87.3% bactericidal activity within 5 cycles. Furthermore, the SPM coating only imparted slight toxic effect (>85% viability) on L929 cells after 36 h of coculture, which is superior to the coating of aminated SPM conjugated with the antimicrobial peptide E6. The terpolymer containing maleic anhydride units have great potential as a flexible and durable coating against implant infections.

Aim: The aim was to evaluate and compare the cell viability, tear bond strength, and shore hardness of MDX4-4210 silicone reinforced with titanium dioxide and silver nanoparticles in 1%, 2%, and 3%., Settings and Design: The study design involves in vitro comparative study., Materials and Methods: MDX4-4210 silicone incorporated with 1%, 2%, and 3% by weight of silver and titanium dioxide nanoparticles. A total of 112 specimens were prepared and grouped into 7, with 16 specimens in each group. Group 1 - control, Groups 2, 3, and 4 were 1%, 2%, and 3% silver, respectively. Groups 5, 6, and 7 were 1%, 2%, and 3% titanium dioxide nanoparticles, respectively. Cell viability was tested by MTT ASSAY on MG63 cell lines, tear bond strength was tested by peeling force in universal testing machine, and Shore A hardness was tested in durometer., Statistical Analysis Used: The cell viability values were statistically analysed using one-way analysis of variance, and Tukey honestly significant difference test, tear bond strength and shore hardness values were analysed using Mann-Whitney test., Results: Based on the MTT ASSAY test, 1% silver nanoparticles incorporated MDX4-4210 silicone showed maximum cell viability of 42.10%, whereas minimum cell viability was 18.06% for 3% of titanium dioxide-reinforced silicone. The mean value of tear bond strength of 1% silver and 1% titanium dioxide nanoparticles reinforced room temperature vulcanized maxillofacial silicone were 62.81 ± 3.637 N/m and 59.69 ± 5.313 N/m and the mean value of shore hardness of room temperature vulcanized of 1% silver and 1% titanium dioxide nanoparticles reinforced room temperature vulcanized maxillofacial silicone were 38.06 ± 1.237 and 36.75 ± 1.291., Conclusion: Cell viability of 1% silver nanoparticles reinforced MDX4-4210 silicone was higher in comparison to the other groups, and tear bond strength and shore hardness were significantly higher in 1% silver nanoparticles reinforced silicone compared to 1% titanium nanoparticles reinforced MDX4-4210 silicone.

Objectives: The antibacterial efficacy of silicone is improved by impregnating it with antimicrobials such as chlorohexidine and zinc oxide. The purpose of this study was to examine mechanical properties and bonding of maxillofacial silicone elastomer mixed with Zinc Oxide nanoparticles (ZnO-NP), and Chlorohexidine Diacetate Salt (CHX) at three different concentrations (1 %, 3 %, and 5 %)., Methods: Specimens of a silicone elastomer (M511) were prepared and divided into 7 groups. Group 1 was control of no additive. Groups 2-4 included silicone elastomer mixed with ZnO-NP (surface area = 67 m 2 /g) at 3 different concentrations (by weight %); 1 %, 3 % and 5 %. Groups 5-7 included silicone elastomer mixed with CHX at the same concentrations. Tear and tensile strengths, elongation percentage, modulus of elasticity, and shear bond strength to primed acrylic resin surfaces were evaluated. Data was analyzed with 1-way ANOVA, Bonferroni, and Dunnett's T3 post-hoc tests (P < 0.05)., Results: There was significant effect of the additives on the tensile strength, elongation percentage, tear strength, and shear bond strength (P < 0.05). Shear bond strengths ranged from 0.55 to 0.96 MPa. Silicone elastomer mixed with CHX (5 %) resulted in the highest shear bond strength (P < 0.05). Non-linear regressions between tensile strength and ZnO and CHX additives were 0.95 and 0.96 respectively., Significance: All additives reduced the tensile strength of the silicone. However, CHX at 5 % optimized shear bond strength and thus is proposed in order to fabricate maxillofacial prostheses of sufficient mechanical properties, bonding and antimicrobial activity., (Copyright © 2023 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Objective: To prepare the hydrogel coating on the surfaces of nasogastric tubes and to evaluate its effect on the insertion of nasogastric tubes in a rabbit model., Methods: The polyacrylamide (PAAm) hydrogel coating was prepared by UV-induced free radical polymerization. The morphology of the PAAm coating and its interfacial bonding with the silicone rubber substrates of nasogastric tubes were observed with scanning electron microscope. The composition of the coating was analyzed by Fourier transform infrared (FTIR) spectrometer and X-ray photoelectron spectrometer (XPS). The water absorption power and stability of the coating were measured by the weighing method. Water contact angle meter was used to measure the wettability of the coating and tribometer was used to determine the friction coefficient of the silicone rubber substrates before and after the modification. The cytotoxicity of the coating on L929 murine fibroblast cell line was explored with CCK-8 assay after 24-h coculturing of the L929 cell line with silicone rubber substrates before and after modification. An animal model of nasogastric tube insertion in New Zealand rabbits was used to evaluate the effect of the lubrication coating by assessing the insertion time and nasal damage., Results: In this study, PAAm hydrogel coating was prepared and constructed on the surface of silicone rubber nasogastric tubes. The coating, with a three-dimensional network structure, showed strong interfacial bonding with silicone rubber substrates. The appearance of amino and carbonyl groups indicated that the PAAm hydrogel coating was grafted on the surfaces of nasogastric tubes. Before the modification, the silicone rubber substrate essentially did not absorb much water, whereas, after the modification, the silicone rubber substrate showed significant improvement of as much as 2.9% in water absorption. After sonication for 90 min, the weight loss rate was only 0.15%. Compared with pristine nasogastric tubes, the water contact angle of the modified nasogastric tubes was reduced from 111.9°±2.2° to 58.9°±1.5° ( t =22.59, P <0.05). In addition, the friction coefficient of silicone rubber nasogastric tubes decreased by 69.3% from 0.378±0.05 to 0.116±0.004 ( t =42.80, P <0.05) after modification. Moreover, there was no significant difference in the cytocompatibility between L929 cells cocultured with pristine nasogastric tube and those cocultured with modified nasogastric tube. The animal experiment of nasogastric tube insertion showed that the insertion time of the modified nasogastric tubes was reduced from (41.6±7.8) s to (12.4±2.9) s ( t =8.509, P <0.05). Laryngoscopy revealed that the PAAm hydrogel coating significantly reduced the mucosal damage caused by the insertion of nasogastric tubes., Conclusion: In this study, PAAm hydrogel coating with strong interfacial bonding was prepared on the surface of silicone rubber nasogastric tubes. The coating has excellent hydrophilic lubrication property and cytocompatibility, effectively shortens the insertion time, and reduces the damage caused by nasogastric tube insertion., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Purpose: To evaluate the effect of different kinds of gingival retraction agents after directly contacted with polyvinyl siloxane impression materials on polymerization inhibition and the inhibition degree., Methods: Five kinds of gingival retraction agents (0.1% epinephrine hydrochloride, 0.05% oxymetazoline, 15.5% ferric sulfate, 25% aluminum chloride and 5% aluminum chloride) were chosen, normal saline was as control group, and two kinds of polyvinyl siloxane impression materials (Express TM , Imprint TM Ⅱ) were combined into 12 groups. There were 12 specimens in each group and 144 specimens in total. Silicone rubber impression materials were mixed by the same operator using a dispensing gun into the acrylic mold, so that they could directly contact the gingival retraction agents on the densely woven cotton fabrics. The samples were removed when the polymerization time arrived according to the manufactures' recommendations and then placed under a stereomicroscope with a magnification of 10 times to observe whether polymerization inhibition occurred, the degree of inhibition was compared afterwards. SPSS 22.0 software package was used for statistical analysis., Results: The polymerization inhibition of two kinds of silicone rubber impression materials occurred in 15.5% ferric sulfate group and 25% aluminum chloride group, and the inhibition occurrence rate was 100%, the difference was statistically significant (P＜0.05) compared with normal saline group. Inhibition was not found in 0.1% epinephrine hydrochloride group, 0.05% oxymetazoline group and 5% aluminum chloride. The effect of 15.5% ferric sulfate and 25% aluminum chloride on polymerization inhibition degree of Imprint TM Ⅱ was greater than Express TM , and the difference was statistically significant(P＜0.05)., Conclusions: When silicone rubber impression material is used during impression procedure, attention should be paid to the effect of the gingival retraction agent containing 15.5% ferric sulfate and 25% aluminum chloride on its polymerization. The gingival retraction agent should be washed before impression to avoid the residue directly contacting the silicone rubber to prevent polymerization.

There is a growing demand for assessing the concentrations of Hydrophobic Organic Contaminants (HOCs) in aquatic environments, including Persistent Organic Pollutants (POPs). The hydrophobicity of POPs challenges their quantification in waters due to the sub-trace concentrations, especially when using conventional spot sampling. The results from the conventional samples are only a "snapshot" of the concentrations (if detected) at the specific sampling moment. Contrary, passive sampling provides average concentration levels over weeks or months from the quantification of accumulated pollutants during the deployment period. The present work compared ethylene vinyl acetate (EVA) and silicon rubber (SR) as monophasic passive samplers to measure dissolved concentrations of HOCs. Four classes of POPs were studied: (i) polychlorinated dibenzo-p-dioxins (PCDDs), (ii) polychlorinated dibenzofurans (PCDFs), (iii) polychlorinated biphenyls (PCBs), including the dioxin-like congeners, and (iv) the polybrominated diphenyl ethers (PBDEs). The polymer-water partition coefficients (K pw ), determined by the cosolvent and crossed calibrations, were, on average, one logarithmic unit larger in EVA than in the SR. The diffusion coefficients (D p ) estimated by the "film-stacking" method were, on average, two orders of magnitude smaller in the EVA than in the SR. For both polymers, the theoretical model of mass transfer resistance confirmed that the water boundary layer controlled the absorption, thus allowing the use of Performance Reference Compounds (PRCs) to estimate the in-situ sampling rates. Larger K pw 's in EVA may be an advantage because they imply longer time scales to reach equilibrium, higher absorption capacities and hence a higher absorbed contaminant mass, especially for compounds that reach equilibrium relatively faster (log K ow < 5). In addition, the longer times to attain equilibrium for EVA maintain this sampler longer in the linear phase of absorption, and the time-weighted average concentration may only be assessed in this phase when the compounds have not yet reached equilibrium., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Bacteria have the extraordinary ability to adhere to biomaterial surfaces and form multicellular structures known as biofilms, which have a detrimental impact on the performance of medical devices. Herein, an investigation highlighted the effective inhibition of bacteria adhesion and overgrowth on silicone rubber surface by grafting polysaccharide, agarose (AG), to construct hydrophilic and negatively charged surfaces. Because of the strong hydration capacity of agarose, the water contact angle of the modified silicone rubber surfaces was significantly reduced from 107.6 ± 2.7° to 19.3 ± 2.6°, which successfully limited bacterial adherence. Most importantly, the durability and stability of coating were observed after 10 days of simulated dynamic microenvironment in vivo, exhibiting a long service life. This modification method did not compromise biocompatibility of silicone rubber, opening a door to new applications for silicone rubber in the field of biomedical materials., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Silicone elastomers are widely used in aviation, electronics, automotive, and medical device fields, and their overuse inevitably causes recycled problems. In addition, the elastomers are subject to attack by bacteria and fire during use in some application scenarios, which is a safety hazard. Therefore, there is a great need to prepare silicone elastomers with improved antibacterial, flame retardant, self-healing, and recyclable functions. A new strategy is proposed to prepare silicone elastomers with bio-based tannic acid as cross-linkers to solve this problem by using polydimethylsiloxane as a soft chain segment and 2,2-bis(hydroxymethyl)propionic acid as an intermediate chain extender. Based on the phenol carbamate bonding and hydrogen bonding interactions, the elastomer has efficient self-healing ability and can achieve dynamic dissociation at 120 °C for complete recovery. In addition, due to the unique spatial structure and polyphenolic hydroxyl groups of tannic acid, the mechanical properties of the elastomer are greatly improved with an antimicrobial efficiency of over 90% and a final oxygen index of 25.5%. The multifunctional silicone elastomer has great potential applications in recyclable refractory materials and antimicrobial materials., (© 2022 Wiley-VCH GmbH.)

Objectives: This work aimed to synthesize a novel injectable alginate impression material and evaluate its accuracy., Methods: Certain proportions of sodium alginate, trisodium phosphate dodecahydrate, potassium fluorotitanate, diatomaceous earth, and other ingredients were dissolved in water and mixed evenly with a planetary centrifugal mixer to obtain a certain viscosity base paste. Certain proportions of calcium sulfate hemihydrate, magnesium oxide, glycerin, and polyethylene glycol (PEG) 400 were mixed evenly with a planetary centrifugal mixer to obtain the reactor paste with the same viscosity as the base paste. The base and reactor pastes were poured into a two-cylinder cartridge at a 2∶1 volume ratio. A gun device was used to accomplish mixing by compressing materials into a mixing tip. The samples were divided into three groups: injectable alginate impression materials (IA group) as the experimental group, and Jeltrate alginate impression materials (JA group) and Silagum-putty/light addition silicone rubber impression materials (SI group) as the two control groups., Results: Scanning electron microscopy (SEM) showed that the injectable alginate impression materials had a denser structure and fewer bubbles than the commercial alginate impression material. The accuracy of the three kinds of impression materials was evaluated by 3D image superposition. The deviations between the three test group models and the standard model (trueness) were 49.58 μm±1.453 μm (IA group), 54.75 μm±7.264 μm (JA group), and 30.92 μm±1.013 μm (SI group). The deviations of the models within each test group (precision) were 85.79 μm±8.191 μm (IA group), 97.65 μm±11.060 μm (JA group), and 56.51 μm±4.995 μm (SI group). Significant differences in trueness and precision were found among the three kinds of impression materials ( P <0.05)., Conclusions: The accuracy of the new injectable alginate impression material was better than that of the traditional powder-type alginate impression material but worse than that of the addition silicone rubber impression materials. The novel injec-table alginate impression material demonstrated good operation performance and impression accuracy, showing broad application prospect.

Aims: Silicone elastomers, chemically known as polydimethylsiloxane used in maxillofacial rehabilitation, over a period of time, undergo degradation and discoloration once aged, thereby reducing clinical longevity. Many previous studies reinforced the maxillofacial silicone material with stronger materials to increase its mechanical properties. However, no studies have been conducted to evaluate all the primary properties using single reinforcing agent. This study was conducted to evaluate and compare the tensile strength, tear strength, color stability, and Shore A hardness of conventional and 1% trisnorbornenylisobutyl polyhedralsilsesquioxanes (POSS) modified room temperature vulcanizing (RTV) maxillofacial silicone after a 6 - month artificial aging period., Setting and Design: In vitro comparative study., Materials and Methods: Eighty-eight silicone samples were fabricated. Therefore for each parameter of tensile strength, tear strength, color stability and hardness, twenty two samples comprising of 11 samples of conventional RTV silicone (Group 1) and 11 for POSS modified RTV silicone (Group 2) were fabricated in stainless steel molds using ASTM D 412-06, ASTM D 624, and ASTM D 2240-15 Standards. Baseline measurements for Shore A hardness and color values were recorded. Samples were then exposed to 6 months of natural weathering process and evaluated for tensile and tear strengths, color stability (ΔE), and hardness., Statistical Analysis Used: Paired and unpaired t-test., Results: Intragroup and intergroup comparison was done using unpaired and paired t-test. At the end of 6-month aging period, the tensile strength and tear strength of POSS-modified RTV silicone were significantly higher than conventional RTV silicone (P < 0.0001 and P = 0.00014, respectively). Intragroup comparison of conventional group showed highly statistically notable changes in L, a, and b values (P = 0.01631, > 0.0001, and = 0.0.0067, respectively), whereas the POSS-modified RTV silicone showed statistically nonsignificant results in L, a, and b values' (P = 0.91722, 0.15174, and 0.10847, respectively) comparisons after aging. Intergroup ΔE value comparisons showed an extremely statistically difference (P < 0.0001) within the groups. Intergroup comparisons postaging hardness showed a high statistical difference between both the groups, indicating a significant increase in hardness in the conventional group (P < 0.0001). However, intragroup comparison for hardness values showed a statistically highly significant difference for Group 1 (P < 0.0001) and a nonsignificant difference (P = 0.4831) for Group 2., Conclusion: After the simulated 6-month aging procedure, 1% NB 1070 trisnorbornenylisobutyl POSS-incorporated RTV maxillofacial silicone showed better tensile strength, tear strength, Shore A hardness and color stability as compared to conventional RTV silicone. Hence, trisnorbornenylisobutyl POSS is a potent cross-linking agent which enhances the primary mechanical properties of RTV silicone can result in in significant increase in the mean life expectancy of RTV silicone even after 6 months of weathering., Competing Interests: None

For many decades, silicone elastomers with oil incorporated have served as fouling-release coating for marine applications. In a comprehensive study involving a series of laboratory-based marine fouling assays and extensive global field studies of up to 2-year duration, we compare polydimethylsiloxane (PDMS) coatings of the same composition loaded with oil via two different methods. One method used a traditional, one-pot pre-cure oil addition approach (o-PDMS) and another method used a newer post-cure infusion approach (i-PDMS). The latter displays a substantial improvement in biofouling prevention performance that exceeds established commercial silicone-based fouling-release coating standards. We interpret the differences in performance between one-pot and infused PDMS by developing a mechanistic model based on the Flory-Rehner theory of swollen polymer networks. Using this model, we propose that the chemical potential of the incorporated oil is a key consideration for the design of future fouling-release coatings, as the improved performance is driven by the formation and stabilization of an anti-adhesion oil overlayer on the polymer surface., (© 2022. The Author(s).)

Infections caused by bacteria and biofilms on the surfaces of biomedical devices and implants pose serious threats to public health. Herein, a nitric oxide (NO) gas-releasing quaternary ammonium-type ionic liquid (IL)-based coating on polydimethylsiloxane (PDMS), PDIL-NO, with effective and long-acting antibacterial and antifouling properties was prepared. N -(2-((2, 3-Dimethylbut-3-enoyl)oxy)ethyl)- N , N -dimethyloctan-1-aminium bromide (IL-Br), and 2-methyl-2-propenoic acid 2-(2-methoxyethoxy) ethyl ester were covalently grafted onto the surfaces of PDMS by a thiol-ene click chemical reaction, followed by incorporation of l-proline anions (Pro - ) through anion exchange with Br - to adsorb NO gas. The prepared PDIL-NO showed a prolonged NO-releasing time (>1440 min) and a relatively high concentration (88 μM). Additionally, PDIL-NO possessed good and long-term antimicrobial activity, and could effectively reduce the adsorption of bovine serum albumin and adhesion of bacteria, as well as inhibit wound infection and reduce inflammation in vivo due to the synergetic effect of IL and the released NO. This study may provide a new approach to combat bacterial infections associated with biomedical devices and implants.

Aim: The aim of the current research was to evaluate the tensile bond strength of a soft liner to the denture base resin with different surface management techniques., Materials and Methods: Dies made up of stainless steel and having dimensions of 40 × 10 × 10 were used to fabricate polymethyl-methacrylate resinous blocks. To make sure of the regularity of the soft liner in the test, dies made up of stainless steel and having dimensions of 10 × 10 × 3 were fabricated to serve as spacers. These acrylic resinous blocks were allocated to three groups depending upon the particular surface management technique as: group I-Absence of surface treatment (Control), group II-Surface management with methyl methacrylate (MMA) monomer, and group III-Surface management with Phosphoric acid. All the samples underwent thermocycling at 5° centigrade and 55° centigrade in two water baths for 500 cycles at a dwell tenure of 30 seconds in every bath to reproduce the oral circumstances. The samples were then subjected to testing in the universal testing machine for evaluation of the tensile strength., Results: The highest tensile strength was noted in the soft liner with denture base resin that was subjected to treatment with a monomer having a mean score of 1.88 ± 0.11 in pursuit by surface management using phosphoric acid at 1.16 ± 0.90 as well as the control group at 0.94 ± 0.02 in that order. There was a statistically noteworthy disparity amid the three dissimilar surface management techniques with a p -value <0.001. There was a statistically noteworthy differentiation amid group I vs group II as well as group II vs group III with a p -value <0.001. However, there was no statistically significant disparity amid group I vs group III with p -value >0.001., Conclusion: The current research arrived at the conclusion that the samples subjected to treatment with MMA monomer exhibited higher and noteworthy bond strength than those attained by additional surface management techniques for soft lining of the denture base resins., Clinical Significance: Soft denture lining materials play a pivotal position in contemporary prosthodontic practice as they possess the ability to restore the health of swollen as well as deformed mucosal tissues. They are comfortable in those individuals who are unable to endure pressure from occlusal forces, like in a situation of residual ridge resorption, sore tissues, and ridges that attain a knife-edge shape. Failing bond causes delamination of the reliner and therefore lack of adaptability of the denture to the oral mucosal tissues. For this reason, superior bonding to the denture base beneath is critical for the clinical triumph of relining agents.

Silicone-rubber baby teats used to bottle-feed infants are frequently disinfected by moist heating. However, infant exposure to small microplastics (<10 μm) potentially released from the heated teats by hydrothermal decomposition has not been studied, owing to the limitations of conventional spectroscopy in visualizing microplastic formation and in characterizing the particles at the submicrometre scale. Here both the surfaces of silicone teats subjected to steam disinfection and the wash waters of the steamed teats were analysed using optical-photothermal infrared microspectroscopy. This new technique revealed submicrometre-resolved steam etching on and chemical modification of the teat surface. Numerous flake- or oil-film-shaped micro(nano)plastics (MNPs) (in the size range of 0.6-332 μm) presented in the wash waters, including cyclic and branched polysiloxanes or polyimides, which were generated by the steam-induced degradation of the base polydimethylsiloxane elastomer and the polyamide resin additive. The results indicated that by the age of one year, a baby could ingest >0.66 million elastomer-derived micro-sized plastics (MPs) (roughly 81% in 1.5-10 μm). Global MP emission from teat disinfection may be as high as 5.2 × 10 13 particles per year. Our findings highlight an entry route for surface-active silicone-rubber-derived MNPs into both the human body and the environment. The health and environmental risks of the particles are as yet unknown., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Flexible wearable electronics play an important role in the healthcare industry due to their unique skin affinity, portability and breathability. Despite great progress, it still remains a big challenge to facilely fabricate stretchable electrodes with low resistance, excellent stability and a wide tensile range. Here, we propose a handy and time-saving strategy for the fabrication of elastomeric films consisting of wave-like fibers with a robust conductive layer of silver nanoparticles (AgNPs) immobilized using polydopamine (PDA) and silicone rubber (SR). To realize better stretchability, electrospun thermoplastic polyurethane (TPU) mats with oriented nanofibers were treated via ethanol to achieve a wavy structure, which also allowed for the decoration of AgNP precursors on the TPU surface via PDA assisted electroless deposition (ELD). Therefore, the electrodes achieved a stretchability of 120% with high electrical conductivity (486 S cm -1 ). The films with a reduction time of 30 min showed superior electrical conductivity indicated by a resistance increase of only 100% within 50% strain. The TPU/PDA/AgNP/SR composites with a shorter reduction time of silver precursors could monitor human motions as wearable strain sensors with a wide work strain range (0-98%) and a high sensitivity (with a gauge factor (GF) of up to 81.76) for a strain of 80-98%. Therefore, they are an excellent candidate for potential application in prospective stretchable electronics.

Inspired by living organisms, soft robots are developed from intrinsically compliant materials, enabling continuous motions that mimic animal and vegetal movement 1 . In soft robots, the canonical hinges and bolts are replaced by elastomers assembled into actuators programmed to change shape following the application of stimuli, for example pneumatic inflation 2-5 . The morphing information is typically directly embedded within the shape of these actuators, whose assembly is facilitated by recent advances in rapid prototyping techniques 6-11 . Yet, these manufacturing processes have limitations in scalability, design flexibility and robustness. Here we demonstrate a new all-in-one methodology for the fabrication and the programming of soft machines. Instead of relying on the assembly of individual parts, our approach harnesses interfacial flows in elastomers that progressively cure to robustly produce monolithic pneumatic actuators whose shape can easily be tailored to suit applications ranging from artificial muscles to grippers. We rationalize the fluid mechanics at play in the assembly of our actuators and model their subsequent morphing. We leverage this quantitative knowledge to program these soft machines and produce complex functionalities, for example sequential motion obtained from a monotonic stimulus. We expect that the flexibility, robustness and predictive nature of our methodology will accelerate the proliferation of soft robotics by enabling the assembly of complex actuators, for example long, tortuous or vascular structures, thereby paving the way towards new functionalities stemming from geometric and material nonlinearities., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Conductive hydrogels are promising multifunctional materials for wearable sensors, but their practical applications require combined properties that are difficult to achieve. Herein, we developed a flexible wearable sensor with double-layer structure based on conductive composite hydrogel, which included the outer layer of silicone elastomer (Ecoflex)/silica microparticle composite film and the inner layer of P(AAm- co -HEMA)-MXene-AgNPs hydrogel. Through covalently cross-linking silicone elastomer on the surface of the hydrogel polymer, we bonded a thin Ecoflex film (100 μm) on the P(AAm- co -HEMA)-MXene-AgNPs hydrogel with robust interface, which can easily adhere to the Ecoflex/SiO 2 microparticle composite film by silicone glue. The Ecoflex/SiO 2 microparticle composite film endows the strain wearable sensor with superhydrophobic function that could maintain the stability under stretching or bending. Moreover, it can effectively resist the interference of water droplets and water flow. The P(AAm- co -HEMA)-MXene-AgNPs hydrogel exhibits outstanding antibacterial activity to inhibit Staphylococcus aureus , Escherichia coli , and even drug-resistant Escherichia coli . In addition, the flexible wearable sensor exhibited good self-adhesive performance by changing the reaction temperature of hydrogel and can adhere strongly onto various materials. The conductive composite hydrogel reported in this work contributes an innovative strategy for the preparation of multifunctional flexible wearable sensor.

Despite technological advancement, nosocomial infections are prevalent due to the rise of antibiotic resistance. A combinatorial approach with multimechanistic antibacterial activity is desired for an effective antibacterial medical device surface strategy. In this study, an antimicrobial peptide, nisin, is immobilized onto biomimetic nitric oxide (NO)-releasing medical-grade silicone rubber (SR) via mussel-inspired polydopamine (PDA) as a bonding agent to reduce the risk of infection. Immobilization of nisin on NO-releasing SR (SR-SNAP-Nisin) and the surface characteristics were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy and contact angle measurements. The NO release profile (7 days) and diffusion of SNAP from SR-SNAP-Nisin were quantified using chemiluminescence-based nitric oxide analyzers and UV-vis spectroscopy, respectively. Nisin quantification showed a greater affinity of nisin immobilization toward SNAP-doped SR. Matrix-assisted laser desorption/ionization mass spectrometry analysis on surface nisin leaching for 120 h under physiological conditions demonstrated the stability of nisin immobilization on PDA coatings. SR-SNAP-Nisin shows versatile in vitro anti-infection efficacy against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in the planktonic and adhered states. Furthermore, the combination of NO and nisin has a superior ability to impair biofilm formation on polymer surfaces. SR-SNAP-Nisin leachates did not elicit cytotoxicity toward mouse fibroblast cells and human umbilical vein endothelial cells, indicating the biocompatibility of the material in vitro . The preventative and therapeutic potential of SR-SNAP-Nisin dictated by two bioactive agents may offer a promising antibacterial surface strategy.

Encapsulation materials play an important role in many applications including wearable electronics, medical devices, underwater robotics, marine skin tagging system, food packaging, and energy conversation and storage devices. To date, all the encapsulation materials, including polymer layers and inorganic materials, are solid materials. These solid materials suffer from limited barrier lifetimes due to pinholes, cracks, and nanopores or from complicated fabrication processes and limited stretchability for interfacing with complex 3D surfaces. This paper reports a solution to this material challenge by demonstrating bioinspired oil-infused slippery surfaces with excellent waterproof property for the first time. A water vapor transmission test shows that locking a thin layer of oil on the silicone elastomer improves the water vapor barrier performance by three orders of magnitude. Accelerated lifetime tests suggest robust water barrier characteristics that approach 226 days at 37 °C even under severe mechanical damage. A combination of temperature- and thickness-dependent experimental measurements and reaction-diffusion modeling reveals the key waterproof property. In addition to serving as a barrier to water, the oil-infused surface demonstrates an attractive ion barrier property. All these exceptional properties suggest the potential applications of slippery surfaces as encapsulation materials for medical devices, underwater electronics, and many others.

Attachment of microbial bodies including the corona virus on the surface of personal protective equipment (PPE) is found to be potential threat of spreading infection. Here, we report the development of a triboelectroceutical fabric (TECF) consisting of commonly available materials, namely, nylon and silicone rubber (SR), for the fabrication of protective gloves on the nitrile platform as model wearable PPE. A small triboelectric device (2 cm × 2 cm) consisting of SR and nylon on nitrile can generate more than 20 V transient or 41 μW output power, which is capable of charging a capacitor up to 65 V in only ∼50 s. The importance of the present work relies on the TECF-led antimicrobial activity through the generation of an electric current in saline water. The fabrication of TECF-based functional prototype gloves can generate hypochlorite ions through the formation of electrolyzed water upon rubbing them with saline water. Further, computational modelling has been employed to reveal the optimum structure and mechanistic pathway of antimicrobial hypochlorite generation. Detailed antimicrobial assays have been performed to establish effectiveness of such TECF-based gloves to reduce the risk from life-threatening pathogen spreading. The present work provides the rationale to consider the studied TECF, or other materials with comparable properties, as a material of choice for the development of self-sanitizing PPE in the fight against microbial infections including COVID-19.

The stability, surface micromorphology, and volatile organic compounds (VOCs) of silicone rubber baking molds (SRBMs) were tested while using the molds under severe conditions: baking at 175 °C, microwaving at 800 W, and freezing at -18 °C. Moreover, migration tests of SRBMs to food simulants (isooctane, 95% ethanol, and Tenax®) at 70 °C for 2 h (accelerated conditions) were performed. The initial total VOCs concentration was 2.53% higher than that recommended by BfR Recommendations on Food Contact Materials. Therefore, the SRBM samples were considered as badly tempered materials, and 18 different types of silicone oligomers were identified during the migration tests. The following percentage of silicone oligomers with a molecular weight lower than 1000 Da in isooctane, 95% ethanol, and Tenax® were detected: 70.7%, 91.8%, and 97.2%, respectively. It has been proven that previous baking treatments effectively reduced the content of silicone oligomers migrating from SRBMs., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Due to high humidity, the ageing of room temperature vulcanized silicone rubber (RTV) has been a serious problem in Southwestern China. In order to solve the problem of RTV life prediction, the aging classification method was established by analyzing the microtopography of RTV samples in this paper. Besides, the comprehensive analysis of RTV element content, partial element content ratio, and major chemical groups of RTV samples in each aging level were conducted. It is found that as the ageing level increases, the element contents of C, Si, O, Al change accordingly and the ratio of C:Si drops from 2.39 to 1.54, and absorption peaks of the chemical groups of Si-(CH3)2, Si-O-Si, Si-CH3 and C-H in CH3 decrease. This work can enrich the investigation of RTV, and may provide useful reference for performance evaluation and replacement of RTV in substations., Competing Interests: The authors have read the journal’s policy and have the following competing interests: LZ and YZ are employees of Electric Power Research Institute, State Grid Shaanxi Electric Power Company. This does not alter our adherence to PLOS ONE policies on sharing data and materials. There are no patents, products in development or marketed products associated with this research to declare.

In view of the development direction of high power and miniaturization of high-voltage power supply, higher requirements are put forward for the breakdown strength, thermal conductivity of packaging materials for its high voltage output module. An electric-insulated heat-conducted material with aluminium nitride as heat conducting filler and addition-cure liquid silicone rubber (ALSR) as matrix for high voltage power encapsulation has been studied. Initially, the thermal conductivity and breakdown strength of composites were explored at different filler fractions. With increase of filler fraction, the thermal conductivity increased and the breakdown strength decreased. Then, with the packaging module volume as the optimization objective and the working temperature as the optimization condition, the temperature distribution of high voltage power supply was studied by using the finite element method, and 40wt% filling fraction was selected as the optimal ratio. Finally, the actual packaging experiment of the high voltage module is carried out. and the variation of the output voltage and temperature with the working time is obtained. According to the experimental results, the output voltage of the high voltage module is basically stable, and the maximum surface temperature is 40.4°C. The practicability of the electric-insulated heat-conducted material has been proved., Competing Interests: The authors have declared that no competing interests exist.

Slide-ring elastomers have garnered a lot of interest for their potential use in dielectric elastomer actuators due to their intrinsically soft nature and high elasticity. However, the use of sliding cross-linkers has been constrained by their low miscibility with commonly used elastomer precursors and the specialized curing chemistries that are necessary for incorporating them into networks. Here, we have presented a method to produce vinyl functional polyrotaxane cross-linkers that are compatible with polysiloxanes and can be processed by industrially scalable methods. The sliding silicone films that were fabricated with these novel cross-linkers were highly extensible (>350%) and did not exhibit strain hardening even at high elongation. The composite films also retained the favorable dielectric properties of silicone elastomers such as the characteristic low dielectric loss. The modified polyrotaxanes present a robust platform for producing a new class of sliding silicone elastomers with well-defined networks structures., (© 2021 IOP Publishing Ltd.)

The long-term stability of condensation curing silicone elastomers can be affected by many factors such as curing environment, cross-linker type and concentration, and catalyst concentration. Mechanically unstable silicone elastomers may lead to undesirable application failure or reduced lifetime. This study investigates the stability of different condensation curing silicone elastomer compositions. Elastomers are prepared via the reaction of telechelic silanol-terminated polydimethylsiloxane (HO-PDMS-OH) with trimethoxysilane-terminated polysiloxane ((MeO) 3 Si-PDMS-Si(OMe) 3 ) and ethoxy-terminated octakis(dimethylsiloxy)-T8-silsesquioxane ((QM OEt ) 8 ), respectively. Two post-curing reactions are found to significantly affect both the stability of mechanical properties over time and final properties of the resulting elastomers: Namely, the condensation of dangling and/or unreacted polymer chains, and the reaction between cross-linker molecules. Findings from the stability study are then used to prepare reliable silicone elastomer coatings. Coating properties are tailored by varying the cross-linker molecular weight, type, and concentration. Finally, it is shown that, by proper choice of all three parameters, a coating with excellent scratch resistance and electrical breakdown strength can be produced even without an addition of fillers.

Engineering rubber composites have been widely used as main components in many fields including vehicle engineering and biomedical applications. However, when a rubber composite surface area is exposed to heat or sunlight and over a long-term accelerated exposure and lifecycle of test, the rubber becomes hard, thus influencing the mechanical and rheological behavior of the materials. Therefore, in this study, the deterioration of rheological characteristics particularly the phase shift angle (δ) of silicone rubber (SR) based magnetorheological elastomer (MRE) is investigated under the effect of thermal aging. SR-MRE with 60 wt% of CIPs is fabricated and subjected to a continuous temperature of 100 °C for 72 h. The characterization of SR-MRE before and after thermal aging related to hardness, micrograph, and rheological properties are characterized using low vacuum scanning electron microscopy (LV-SEM) and a rheometer, respectively. The results demonstrated that the morphological analysis has a rough surface and more voids occurred after the thermal aging. The hardness and the weight of the SR-MRE before and after thermal aging were slightly different. Nonetheless, the thermo-rheological results showed that the stress-strain behavior have changed the phase-shift angle (δ) of SR-MRE particularly at a high strain. Moreover, the complex mechanism of SR-MRE before and after thermal aging can be observed through the changes of the 'in-rubber structure' under rheological properties. Finally, the relationship between the phase-shift angle (δ) and the in-rubber structure due to thermal aging are discussed thoroughly which led to a better understanding of the thermo-rheological behavior of SR-MRE.

Background: With the enormous increment of globalization and global warming, it is expected that the number of newly evolved infectious diseases will continue to increase. To prevent damage due to these infections, the development of a diagnostic method for detecting a virus with high sensitivity in a short time is highly desired. In this study, we have developed a disposable electrode with high-sensitivity and accuracy to evaluate its performances for several target viruses., Results: Conductive silicon rubber (CSR) was used to fabricate a disposable sensing matrix composed of nitrogen and sulfur-co-doped graphene quantum dots (N,S-GQDs) and a gold-polyaniline nanocomposite (AuNP-PAni). A specific anti-white spot syndrome virus (WSSV) antibody was conjugated to the surface of this nanocomposite, which was successfully applied for the detection of WSSV over a wide linear range of concentration from 1.45 × 10 2 to 1.45 × 10 5 DNA copies/ml, with a detection limit as low as 48.4 DNA copies/ml., Conclusion: The engineered sensor electrode can retain the detection activity up to 5 weeks, to confirm its long-term stability, required for disposable sensing applications. This is the first demonstration of the detection of WSSV by a nanofabricated sensing electrode with high sensitivity, selectivity, and stability, providing as a potential diagnostic tool to monitor WSSV in the aquaculture industry.

Although silicone implants are the most popular choice around the world for breast augmentation, reconstruction, and revision, due to the poor antibacterial properties and limited biocompatibility of silicone rubber (SR), one of the major complications, capsule contracture, is a lingering problem. To overcome the two main shortcomings, a dual ion implantation technique was applied to modify the surface of SR with the basic skeleton element of organic matter, carbon (C) and the broad-spectrum bactericide, silver (Ag). We present surface characterization, toxicological effects, and evaluation of the mechanical, antibacterial and biocompatible properties of C and Ag co-implanted SR (C/Ag-SRs). After ion implantation, surface roughness and tensile strength of these new materials increased. Biotoxicity was fully assessed by in vitro experiments on human fibroblasts and in vivo experiments on rats, showing that the low-Ag groups met safety standards. Both the anti-bacterial adhesion and bactericidal abilities of C/Ag-SRs were superior to those of SR, which had few antibacterial activities, especially against Staphylococcus epidermidis. With respect to biocompatibility, the adhesion of fibroblasts was promoted, while their proliferation was moderately inhibited on ion-implanted surfaces. After subcutaneous implantation in rats for 7, 30, 90 and 180 d, the capsular thickness around C/Ag-SRs was significantly lower than that around the SR. Additionally, there was no difference in the inflammatory reaction after 7 d of retention in vivo between C/Ag-SRs and SR. The results demonstrate that C/Ag-SRs are desirable shell materials for breast implants.

Due to their high biocompatibility silicone elastomers are the material of choice in many sensitive health care applications. However, the inherent hydrophobicity of the polymer makes silicones more susceptible to spontaneous protein adsorption and subsequent biofilm formation than more hydrophilic abiotic materials. Hence, the development of antimicrobial silicone elastomers could help to reduce potential biofilm-associated infections when using silicone based medical devices. In this study, we describe carboxylic-acid-modified silicone elastomers that are biocompatible and exhibit a specific antimicrobial activity against clinically relevant pathogens even after being stored in common packaging materials., Competing Interests: Declaration of competing interest The authors Andreas Koellnberger, Rainer Schrader, Christoph Briehn declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Significance: Lotrafilcon B lenses packaged in and cared for with block copolymer-containing (polyoxyethylene-polyoxybutylene; EOBO) lens care solutions resulted in lower cholesterol extraction than each of the habitual silicone hydrogel lens/multipurpose solution (MPS) regimens tested., Purpose: This study aimed to compare the extracted cholesterol of lotrafilcon B lenses packaged in and cared for with EOBO-containing lens care solutions with the extracted cholesterol of habitual silicone hydrogel lenses cared for with MPS not containing EOBO., Methods: In this prospective, randomized, observer-masked parallel study, habitual wearers of senofilcon C, senofilcon A, comfilcon A, and samfilcon A contact lenses using a non-EOBO MPS were randomized 1:1 to lotrafilcon B lenses packaged in and cared for with EOBO-containing solutions or to their habitual lenses and MPS. Subjects randomized to lotrafilcon B were further randomized to one of two EOBO-containing lens care solutions, OPTI-FREE PUREMOIST or CLEAR CARE PLUS with HydraGlyde (Alcon Laboratories, Inc., Fort Worth, TX). A subset of right eye lenses was collected after wear, and total cholesterol was extracted and measured using a fluorometric enzymatic assay., Results: Of 143 lenses analyzed, 95 were from subjects randomized to their habitual lenses/MPS and 48 to lotrafilcon B + EOBO lenses plus CLEAR CARE PLUS with HydraGlyde or OPTI-FREE PUREMOIST. The mean amounts of cholesterol extracted from lotrafilcon B + EOBO lenses cared for with CLEAR CARE PLUS with HydraGlyde (0.28 ± 0.18 μg/lens) and OPTI-FREE PUREMOIST (0.28 ± 0.48 μg/lens) were significantly lower than those extracted from senofilcon C (4.18 ± 3.25 μg/lens), senofilcon A (2.19 ± 2.69 μg/lens), comfilcon A (2.17 ± 1.47 μg/lens), and samfilcon A (2.07 ± 1.48 μg/lens) lenses used with MPS (P < .0001 each)., Conclusions: Cholesterol sorption was significantly lower in wearers of lotrafilcon B lenses cared for with polyoxyethylene-polyoxybutylene-containing lens care solutions than in users of habitual silicone hydrogel lenses cared for with non-polyoxyethylene-polyoxybutylene MPS.

Drift tube ion mobility spectrometers (DT IMS) allow the concentration of different organic compounds to be measured. This gives the opportunity to use these detectors in measuring the penetration of various substances through polymer membranes. Permeation measurements of two substances (2-heptanone and dimethyl methylphosphonate (DMMP)) through a cylindrical silicone rubber membrane were carried out. The membrane separated the aqueous solution from the air. The analyte was introduced into water, and then its concentration in air on the opposite side of the membrane was recorded. Based on the dynamics of detector signal changes, the diffusion coefficients for both tested substances were determined. Determination of permeability coefficients was based on precise quantitative measurements, which took into account the non-linearity of the detector characteristics and the effect of water on detection sensitivity. The analysis of measurement results was based on a mathematical description of diffusion process.

The joint membrane of the American lobster shows an excellent combination of high strength, toughness, and defect tolerance due to the periodic helicoidal stacking of the fiber layers that are connected by a weak continuous matrix. Inspired by the joint membrane of American lobsters, we simply use nonwoven fabrics and silicon rubber to fabricate a multilayer soft composite with the helicoidal stacking and controllable matrix. The influences of stacking structure, matrix strength, fabrics strength, and notch size on the fracture behavior of the soft composite during the tensile process are systematically analyzed by both experimental tests and finite element analysis (FEA). We find that similar to the joint membrane, the soft composite demonstrates a gradual failure process and a linear relationship between tensile strength/toughness and notch size. Such phenomena demonstrate the strong defect-tolerant ability, thereby imparting the soft composite with both high strength and toughness. The defect-tolerant ability is closely related to the helicoidal stacking and weak matrix between the fabrics layers, which induce crack deflection and inhibit the propagation of cracks across the sample.

Polydimethylsiloxane (PDMS) film with significantly enhanced water permeability and uptake was prepared by incorporating spherical elastic hollow microcapsules (eHMCs) in it. eHMCs were prepared through O/W/O emulsification method. Water permeability and uptake of the film increased significantly in proportion to the amount of embedded eHMCs while minimizing the changes in elastic characteristics and transparency of PDMS. The release rate of loaded water soluble model drug from the eHMC-embedded PDMS film could be controlled by the magnitude of uniaxial mechanical stimulus applied over the film and initial drug loading amount, with negligible release of drug from the film in the absence of external stimulation. Thus, these biocompatible and elastic composite PDMS films are potentially useful, including as an easily accessible and instantly effective way of controlling hydrophilic drug release using the mechanical stimulus as well as a soft elastomer with enhanced water uptake and permeability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)