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Heptamethine based cyanines, namely 1,3,‐trimethyl‐2‐(2‐2[2‐phenylsulfanyl‐3‐[2‐(1,3,3‐trimethyl‐1,3,3‐trithyl‐1,3‐dihydro‐indol‐2‐ylidene)‐ethylidene]cyclohex‐1‐enyl]vinyl)‐3H‐indolium chloride (S1) and 2‐[2‐(2‐chloro‐[2‐[1,1‐dimethyl‐7‐sulfo‐3‐(4‐sulfobutyl)‐1,3‐dihydro‐benzo[e]indol‐2‐ylidene]‐ethylidene]cyclopent‐1‐enyl]vinyl]‐1,1‐dimethyl‐7‐sulfo‐3‐(4‐sulfobutyl)‐1Hbenzo[e]indolium hydroxide, inner salt, triethylammonium salt (S2), efficiently result in physical drying of an aqueous dispersion comprising a polyurethane binder. S2 possesses a water solubility of 40 g/L. A high‐intensity near‐infrared‐LED emitting at 820 nm with an intensity of 1 W/cm2 served as light source. The cyanine converted the light absorbed into heat by internal conversion needing less drying time compared to conventional drying. Water content after film formation showed less then 1%. In the second step, ultraviolet (UV) exposure with a LED emitting at 395 nm resulted in formation of semi‐interpenetrating polymer networks by crosslinking of the multifunctional (meth)acrylate operating as reactive diluent. Ethyl phenyl(2,4,6‐trimethylbenzoyl)phosphinate‐L served as effective UV‐photoinitiator. Furthermore, the UV‐exposure together with Norrish Type I and Type II photoinitator systems results in a very efficient bleaching of the green physical dried film. This contribution shows for the first time a new photonic hybrid technique describing successful replacement of an oven‐based process by a photonic based step that generates heat needed for drying. [ABSTRACT FROM AUTHOR]

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This paper extends previous studies by the authors that aimed to describe the effect of apparent cross-link density (CLD) of the rubber polymer networks on the fracture mechanism caused by cut and chip (CC) wear of natural rubber (NR), demonstrating the positive effect of conventional vulcanization (CV). This work is focused on the determination of the effect of CLD while keeping constant the accelerator-to-sulfur ratio A/S = 0.2, typical for CV systems. For this ratio, different sulfur quantities were chosen, and the concentration of the accelerator N-tert-butyl-benzothiazole sulphonamide (TBBS) was calculated to achieve CLDs in a range from 35 to 524 μmol・cm–3. Standard analyses such as tensile tests, hardness, rebound resilience and DIN abrasion were performed. From these analyses, the optimum physical properties of the NR-based rubber were estimated to be in the CLD range of approximately 60 to 160 μmol・cm–3. A CC wear analysis was performed with an Instrumented cut and chip analyzer (ICCA) and it was found that the highest CC wear resistance of the NR is in the CLD range of 35 to 100 μmol・cm–3. Furthermore, the effect of straininduced crystallization (SIC) of NR on CC wear and its dependence on the CLD region was discussed. For the first time, we determine a CLD range for a CV system in which the material achieves both optimal mechanical properties and CC wear resistance.

Poly(vinyl alcohol) (PVA) based hydrogels have gained more interest in the field of biomaterials because of their many biomedical uses (i.e., wound healing, drug delivery, and tissue engineering) and intrinsic physicochemical and biological characteristics. They can be made using a variety of synthetic techniques, but all of them are very time-consuming. Among them, photopolymerization also referred to as light-induced polymerization, has drawn a lot of attention because of its benefits, which include not requiring the use of solvents, easy and quick network formation, energy efficiency, quick processing, control over both space and time and reliability of crosslinking density and matrix strength. Ultraviolet (UV)-curable hydrogels containing PVA as a main component are gaining interest because of their excellent properties, including biodegradability, biocompatibility, less cytotoxicity and remarkable mechanical strength. This review highlights the significance of UV curable systems and their components, types, advantages and disadvantages of photoinitiators (PIs), UV curable monomers and their structures, properties of UV-cured PVA hybrid hydrogels, and their characterizations and applications in different fields. The photopolymerization mechanisms, tunable properties, and unique advantages of these hydrogels have been explored in detail. Furthermore, it sheds light on recent advancements in PVA-based hydrogels research and future exploration in this domain.

Epoxidized natural rubber with 50 mol% epoxide (ENR-50) was compounded with zinc chloride (ZnCl2) and subjected to torque response analysis using a moving die rheometer. It was found that different ZnCl2 concentrations (3, 5, 7, 9, and 12 millimoles (mmol)) mixed in ENR-50 exhibited positive torque responses, prompting further molecular characterization using Fourier transform infrared spectroscopy. The results indicated distinct absorption peaks at wavenumbers of 442 and 809 cm–1, which signify the presence of –O–Zn–O– coordination linkages. The curing characteristics of ENR and ZnCl2 compounds showed that increasing ZnCl2 content resulted in higher minimum and maximum torque values, but also led to a decrease in scorch time and cure rate index (CRI). Moreover, higher ZnCl2 concentrations enhanced the strength properties (tensile strength, moduli, stiffness, toughness, and hardness), crosslink densities, dynamic shear moduli, initial modulus during relaxation experiments, and thermal resistance, as evidenced by temperature scanning stress relaxation (TSSR), thermogravimetric analysis, and dynamic mechanical analysis. However, an increase in ZnCl2 content led to a reduction in elongation at break due to the higher crosslink density within the coordination networks in the ENR matrix, which resulted in the movement constraint of the rubber vulcanizate.

Research into sustainable packaging materials has gained increasing importance due to the pressing environmental concerns related to plastic waste. The present study focused on developing a sustainable paper coating based on modified natural rubber (NR) latex filled with gelatin (GT). The graft copolymer latex of NR and poly(vinylbenzyl chloride) bearing quaternary ammonium groups, abbreviated as NR-g-QPVBC, was first synthesized. GT was then incorporated into the latex, and the combination of these materials resulted in a heat-sealable film with good tensile properties and a water barrier. The ionic crosslinking of the latex film was achieved by the reaction with ethylenediaminetetraacetic acid (EDTA). Heat-sealing studies of the NR-g-QPVBC latex film filled with GT (NR-g-QPVBC/GT) revealed its heat-sealability at 160 °C. Scanning electron microscope (SEM) analysis further confirmed the diffusion of the chains across the interface during heat sealing. Dip coating was a method for depositing latex film on kraft paper. The paper coated with the NR-g-QPVBC/GT latex showed a significant increase in dry and wet-tensile strength compared to the uncoated paper. The sealing process was optimized to achieve a heat-seal strength of 755.31 N/m at a dwell time of 3 s and a temperature of 160 °C. The research's practical application was demonstrated by transforming the coated paper into various heat-sealable bags using a handheld bag sealer.

Natural rubber (NR) composites reinforced with sepiolite and crosslinked with phenolic resin were prepared. Effects of compatibilizer types and contents, namely 3-aminopropyl triethoxysilane (APTES) or epoxidized NR (ENR50), on curing, tensile, strain-induced crystallization, and stress relaxation were investigated. Compared to APTES, ENR50 provided a greater compatibilizing effect in the NR composites. The ENR50 introduced strong physical and chemical interactions between sepiolite and NR, while only physical interaction was present in the APTES compatibilized composites. Stronger interaction between rubber and sepiolite improved filler dispersion, swelling resistance, and tensile strength; and delayed stress relaxation of the composite. Increased addition of ENR50 improved the modulus and tensile strength, and the greatest tensile strength was achieved at 2 phr ENR50 with a 15% improvement over composite without compatibilizer. In the case of APTES, 2 phr level enhanced tensile strength, but a further increase in APTES content degraded tensile, swelling resistance, and stress relaxation responses, due to its plasticizing effect. Moreover, ENR50 enhanced the strain-induced crystallization and delayed stress relaxation of the composites more than APTES. Weaker interaction between rubber and filler in APTES filled composites was due to having only hydrogen bonds formed between rubber and filler, in addition to crosslinks.

Abstract Corneal crosslinking (CXL) is a widely applied technique to halt the progression of ectatic diseases through increasing the thickness and mechanical stiffness of the cornea. This study investigated the biocompatibility and efficiency of a novel CXL procedure using ruthenium and blue light in rat corneas and evaluated parameters important for clinical application. To perform the CXL procedure, the corneal epithelium of rats was removed under anaesthesia, followed by the application of a solution containing ruthenium and sodium persulfate (SPS). The corneas were then exposed to blue light at 430 nm at 3 mW/cm2 for 5 min. Rat corneas were examined and evaluated for corneal opacity, corneal and limbal neovascularization, and corneal epithelial regeneration on days 0, 1, 3, 6, 8, and 14. On day 28, the corneas were isolated for subsequent tissue follow-up and analysis. CXL with ruthenium and blue light showed rapid epithelial healing, with 100% regeneration of the corneal epithelium and no corneal opacity on day 6. The ruthenium group also exhibited significantly reduced corneal (p

Abstract Background Wound healing represents a complex biological process, critically important in clinical practice due to its direct implication in a patient’s recovery and quality of life. Conservative wound management frequently falls short in providing an ideal environment for the optimal tissue regeneration, often resulting in extended healing periods and elevated risk of infection and other complications. The emerging biomaterials, particularly hydrogels, have shown substantial promise in addressing these challenges by offering properties such as biocompatibility, biodegradability, and the ability to cure wound environment. Recent advancements have highlighted the therapeutic potential of integrating cell-derived conditioned medium (CM) into hydrogel matrices. Cell-derived CM represents a rich array of bioactive molecules, demonstrating significant efficacy in modulating cellular activities crucial for wound healing, including cellular proliferation, migration, and angiogenesis. Methods The methodology of this review adheres to the standards set by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The review includes a selection of studies published within the last five years, focusing on in vivo experiments involving various types of skin injuries treated with topically applied hydrogels loaded with CM (H-CM). The search strategy refers to the PICO framework and includes the assessment of study quality by CAMARADES tool. Results The systematic review represents a detailed evaluation of H-CM dressings wound healing efficiency based on the experimental results of cell-based assays and animal wound models. The study targets to reveal wound healing capacity of H-CM dressings, and provides a comparative data analysis, limitations of methods and discussions of H-CM role in advancing the wound healing therapy. Conclusions The data presented demonstrate that H-CM is a promising material for advanced wound healing and regenerative medicine. These dressings possess proved in vitro/in vivo efficacy that highlights their strong clinical potential and paves the way to further investigations of H-CM formulations within clinical trials.

Purpose. To evaluate the effectiveness and safety of direct current cornea fulguration in the treatment of drug-resistant keratitis. Material and methods. 20 patients (20 eyes) diagnosed with drug-resistant infectious keratitis (bacterial, acanthamoeba, fungal), underwent fulguration of the infiltration zone with plasma electrocautery. In addition to a standard ophthalmological examination, all patients were tested for corneal thickness and lesion depth before surgery and 1 day, 1 month, and 3 months after surgery by anterior segment optical coherence tomography (OCT). After photofixation of the cornea, OCT data were used to dynamically assess the lesion area and deepithelialization. Results. In 95 % of cases (19 eyes), the infectious inflammatory process could be stopped in 3 to 7 weeks, with the opacification onset in the stromal layers of the cornea 2–3 weeks after the procedure. In these cases, after 2 weeks, the infiltrated or corneal ulcer area was completely epithelialized. Over a long postprocedural period (3 months), the corneal thickness in the inflammation area varied from 285 µm to 791 µm. During the entire observation period, the integrity of the cornea was maintained and transparency improved. 3 months after surgery, the average visual acuity corrected by spectacle lenses increased from 0.42 ± 0.35 to 0.54 ± 0.33. Conclusion. Direct current fulguration can be an effective and relatively safe urgent treatment for drug-resistant infectious keratitis.

Abstract Glutaraldehyde (GTA) crosslinking is commonly used to improve the thermal stability and mechanical strength of collagen casings. The aim of this research was to determine the optimal pH of the crosslinking between GTA and collagen as well as the crosslinking mechanisms. The weakly alkaline environment could facilitate the generation of GTA polymerization through the rapid generation of -C = C-C = O and -N = C-C = C- conjugated structures, and enhance the crosslinking reaction of GTA polymers with collagen amino groups. In the pH range of 8–10, the fibril diameter and d-space value declined significantly in the self-assembled collagen fibril-GTA system. Meanwhile, collagen casing films crosslinked with GTA in weakly alkaline conditions exhibited higher mechanical strength and thermal stability. These results suggest that the crosslinking of collagen casings and GTA can be improved by adjusting the pH. Possible crosslinking mechanisms related to the formation of conjugated long chains have also been proposed. This study could provide guidance on the appropriate use of GTA in the production process of collagen casings. Graphical Abstract

This study addresses the increasing demand for eco-friendly rubber compounding additives by exploring greensynthesized zinc oxide (ZnO) nanoparticles. The green synthesis of ZnO nanoparticles is gaining attention due to its ecofriendly approach and potential applications. This study investigates the synthesis of ZnO nanoparticles using sweet lime peel extract as a green method, comparing it with chemical synthesis. The obtained nanoparticles are characterized and evaluated for suitability as activators in natural rubber composites for tire applications. Furthermore, the cytotoxicity of the prepared ZnO nanoparticles on mice cells is assessed, revealing lower toxicity for green-synthesized ZnO compared to chemically synthesized ZnO. Payne effect analysis on the composites demonstrates improved polymer-filler interaction and mechanical properties for the green-synthesized ZnO-loaded composites. Notably, the incorporation of green-synthesized ZnO leads to significant enhancements in tensile strength due to its higher surface area. It achieves desirable magic triangle tire properties, including low rolling resistance, high wet traction, and high abrasion resistance. These findings highlight the promising potential of green ZnO as an environmentally friendly alternative to chemical ZnO in rubber compounding.

Induced corneal collagen crosslinking and mechanical stiffening via ultraviolet-A photoactivation of riboflavin (UVA CXL) is now a common treatment for corneal ectasia and Keratoconus. Some effects of the procedure such as induced mechanical stiffening, corneal flattening, and cellular toxicity are well-known, but others remain more controversial. Authors report a variety of contradictory effects, and provide evidence based on individual results and observations. A full understanding of the effects of and mechanisms behind this procedure are essential to predicting its outcome. A growing interest in modifications to the standard UVA CXL protocol, such as transepithelial or accelerated UVA CXL, makes analyzing the literature as a whole more urgent. This review presents an analysis of both the agreed-upon and contradictory results reported and the various methods used to obtain them.

The environmental and ecological concerns drive researchers to synthesize functional materials using components from natural resources. Nanocellulose (NC), derived from plants, marine animals, or microorganisms, is a green material attracting attention due to its abundance, biocompatibility, and biodegradability. NC’s interstice properties enable the synthesis of functional nanocomposites in forms like aerogels, foams, paper, sheets, or hollow filaments. This review briefly describes NC classification and production while comprehensively presenting its mechanical, rheological, optical, and electrical properties, offering foundational knowledge for future research. Additionally, it highlights recent developments in NC-based products across fields such as papermaking, water treatment, civil engineering, electronics, cosmetics, food, and medicine. For the first time, this paper explores recent advances in NC molecular simulation, providing insights into structure, arrangement, and interactions through molecular dynamic simulation. Finally, future prospects for NC-based applications are discussed to encourage studies addressing current challenges.

Dynamic cross-linked networks (DCNs) endow thermoset rubber with self-healability and recyclability to extend its lifetime and alleviate environmental pollution. However, the contradiction between high self-healing and mechanical properties in DCNs rubber is always difficult to be resolved. Herein, we used boronic ester (BO) and Diels-Alder dynamic covalent bonds (DA) to synthesize polybutadiene-based dual networks rubber (PB-BO-DA) via thiol-ene reaction. This approach achieved a tensile strength of 16.46 MPa and 99% self-healing efficiency, facilitated by extensive intermolecular interactions (π-π packing and N-B coordination) and fully dynamic cross-linking. In addition, multiple dynamic cross-linked networks (MDCNs) polybutadiene-based rubber also show excellent shape memory ability and recyclability. This strategy might open a helpful pathway to fabricate intelligent multifunctional polymers with high strength and high self-healing efficiency.

Abstract Background Wound healing is a natural but complex process that can be delayed by infection. Rosuvastatin calcium (RVS) is an anti-hyperlipidemic that was recently reported to have a wound healing capability. The study aimed to investigate the impact of combining RVS with Levofloxacin (LV) on wound healing. A physically crosslinked polyvinyl alcohol (PVA) film loaded with RVS and LV was formulated as wound dressing. Formulation optimization was carried out using Box–Behnken design. The effect of independent variables (PVA and propylene glycol concentrations and the number of freeze–thaw cycles) on tensile strength (TS), elongation to break (%EB) and in vitro drugs’ release was studied. For simultaneous RVS and LV quantification in the formulations and pure form, three spectrophotometric methods: derivative of ratio spectrophotometry, first derivative and mean centering, were developed. Also, their greenness was evaluated by the Analytical Eco-Scale and the Green Analytical Procedure Index. Then, the wound healing effect of the optimized wound dressing was evaluated in rat models. Results The optimized dressing had sufficient mechanical strength (9.45 ± 0.67 MPa), adequate flexibility (112.6 ± 3.8% EB) and suitable drug release (52.3 ± 1.4% for LV and 38.99 ± 1.6% for RVS after 12 h). The proposed methods were validated following ICH guidelines, and greenness assessment suggested their very low environmental effect. The wound healing evaluation showed a higher wound contraction percentage when RVS was combined to LV. A histopathological study confirmed marked improvement in animals treated with combined formula with lowest inflammatory infiltration and optimum epithelialization, compared to other groups. Conclusion Study findings suggest that combined LV-RVS dressing would be a beneficial platform with potentiated wound healing capacity. Graphic abstract

Abstract Resistant starch from plantain (Macho Musa paradisiaca L.) and banana (Roatan Musa sapientum L.) varieties was chemically modified by crosslinking using epichlorohydrin (EPI). These modified starches were subjected to in vitro digestibility studies using the Englyst method to determine the content of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). The thermal stability of these crosslinked starches was evaluated by gelatinization and retrogradation analyses, and their enthalpies were determined using differential scanning calorimetry (DSC). Additionally, their functional properties were evaluated. Chemical modification with EPI significantly increased the RS content in both starch varieties compared to that in native starch. The enthalpy and gelatinization temperature decreased in the EPI-modified starches of both varieties, indicating lower thermal stability during the gelatinization process compared to that of native starch. In general, both varieties of crosslinked plantain starch had lower viscosity (0.43 Pa*s) than did native starch (0.58 Pa*s). The results indicates that this starch crosslinked with EPI constitutes an alternative for use in food for people with health problems such as high cholesterol levels or postprandial insulin concentrations. Graphical Abstract

Electron beam (EB) treatment of a high vinyl styrene-butadiene-styrene (SBS) block copolymer was accomplished by exposing the polymer to high-energy electrons generated from an electron accelerator. This resulted in the formation of free radicals of carbon on the polybutadiene units in the backbone of the elastomer and subsequent radical coupling to produce cross-links. In the process, some unavoidable chain scission (CS) also occurred. An attempt was made to mathematically trace the nature of the CS as a function of radiation dose with the aid of the experimentally determined cross-link density (CLD), tensile strength and tear strength, the latter three also obtained as functions of radiation dose. The radiation dose was varied from 12.5 to 300.0 kGy in multiples of 12.5 kGy. The novelty of the work was, in part to create a function that can be used to calculate chain-scission in dependence of EB radiation dose. It was found that a change in the ratio of CS to CLD occurred as a function of radiation dose over the previously calculated constant ratio, using the Charlesby-Pinner equation.

Abstract Deoxyribonucleotide (DNA) is uniquely programmable and biocompatible, and exhibits unique appeal as a biomaterial as it can be precisely designed and programmed to construct arbitrary shapes. DNA hydrogels are polymer networks comprising cross-linked DNA strands. As DNA hydrogels present programmability, biocompatibility, and stimulus responsiveness, they are extensively explored in the field of biomedicine. In this study, we provide an overview of recent advancements in DNA hydrogel technology. We outline the different design philosophies and methods of DNA hydrogel preparation, discuss its special physicochemical characteristics, and highlight the various uses of DNA hydrogels in biomedical domains, such as drug delivery, biosensing, tissue engineering, and cell culture. Finally, we discuss the current difficulties facing DNA hydrogels and their potential future development. Graphical Abstract

Objective: The aim was to evaluate the effect of oligo-chitosan modification on the properties of gelatin-based films. Methods: The gelatin-based films were prepared by using gelatin extracted from scrap pig skin as a cheap raw material and chitosan and polyvinyl alcohol as cross-linking agents. The structural and mechanical properties were characterized by Fourier infrared spectroscopy, X-ray power diffractometry, scanning electron microscopy, spectroscopy, and tensile test. Meanwhile, the ability of gelatin-based films in antioxidant, antibacterial, water stability and biodegradation were evaluated. Results: The multi-cross-linked gelatin-based films showed excellent mechanical properties, with a highest fracture stress of 37.09 MPa, a maximum tearing energy of 56.71 kJ/m2, and a good physical form maintained after 48 h of immersion in water. In addition, the films possessed excellent light transmission (up to 92.32%), good oxidation resistance (radical scavenging capacity up to 75.12%), excellent antimicrobial and biodegradability (complete degradation time

Silicone rubber magnetorheological elastomers (SR-MREs) are increasingly recognized for their resilience in marine conditions, offering prolonged service life and durability. This study evaluates the one-month durability of silicone rubber magnetorheological elastomers (SR-MREs) under seawater conditions. Results revealed a 6% reduction in hardness and an 8% decrease in Young’s modulus compared to unimmersed samples. Morphological and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analyses supported these findings, revealing surface defects and chemical bonding changes. The immersed SR-MRE displayed a notable 250% increase in elongation at break, highlighting enhanced elasticity. Rheological properties revealed complex mechanical behavior, with an initial increase in storage modulus from 0.25 to 0.38 MPa in the presence of a magnetic field, followed by a gradual decrease to 0.15 MPa at 0 A and 0.52 Mpa at 5 A with strain. Additionally, this study proposes an illustrative mechanism to elucidate the relationship between seawater elements and SR-MRE behavior, enhancing our understanding of its mechanical properties and degradation in marine environments, thus highlighting SR-MRE’s potential as a durable material compared to traditional rubber composites.

This work reported a practical approach to turning conventional natural rubber (NR) into a thermally healable rubber. 4-vinylbenzyl chloride was first polymerized in the NR latex to yield graft copolymers of NR and poly(vinylbenzyl chloride), NR-g-PVBC. The cutting and rejoining process was used to study the healing ability of latex film. The healing behavior was observed after the reassembled film was heated at 100 °C for 1 h and then allowed to heal continuously at room temperature (RT). The healed film displayed a 58.44% regain of the tensile strength (4.57 MPa) after being allowed to recover at RT for 72 h. Additionally, the chloromethyl moieties in the NR-g-PVBC could be converted into quaternary ammonium (QA) groups by reaction with trimethylamine, producing the quaternized NR-g-PVBC (NR-g-QPVBC). Ionic crosslinking of the NR-g-QPVBC film was achieved by incorporating sodium tripolyphosphate (STPP). The latex film had a tensile strength of 15.32 MPa and could withstand a strain of 868% when ionically cured with 2 phr of STPP. After the healing process, the cured film showed a healing efficiency of 49.67% in tensile strength (7.61 MPa). Furthermore, a suturing test was performed to investigate the feasibility of developing a suture training pad from the corresponding cured film. The film’s ability to heal with heat assistance was its significant practical advantage, enhancing its realism and mimicking the healing process in human skin.

A porous, crosslinked aromatic polyamide having COCl and COOH groups (referred to as PA herein) prepared had a mesoporous structure and comprised agglomerates of particles with average diameters of approximately 30 nm. The PA was found to swell with significant deformation in response to water vapor, but was almost unchanged after exposure to toluene vapor. The polymeric structure returned to its original porous morphology after removal of the solvents, demonstrating that the PA possessed affinity for specific solvents and shape memory. The chemical composition and porous structure of the PA were also not affected by heating to 330 °C. The COCl groups in the PA could be modified by reaction with 2,4,6‐triaminopyrimidine (TAP), resulting in a doubly crosslinked structure based on the reaction with the TAP as well as the existing amide moieties in the polymer. The degree of modification was highly dependent on the reaction solvent used. The porous structure of the PA was essentially unchanged after this modification. The TAP‐based crosslinks in the modified PA could be selectively cleaved along with vaporization of the TAP by heating at 330 °C, which no change to the porous structure. Thus, the PA showed excellent heat resistance and structural stability. [ABSTRACT FROM AUTHOR]

Background: Wound healing is a natural but complex process that can be delayed by infection. Rosuvastatin calcium (RVS) is an anti-hyperlipidemic that was recently reported to have a wound healing capability. The study aimed to investigate the impact of combining RVS with Levofloxacin (LV) on wound healing. A physically crosslinked polyvinyl alcohol (PVA) film loaded with RVS and LV was formulated as wound dressing. Formulation optimization was carried out using Box–Behnken design. The effect of independent variables (PVA and propylene glycol concentrations and the number of freeze–thaw cycles) on tensile strength (TS), elongation to break (%EB) and in vitro drugs' release was studied. For simultaneous RVS and LV quantification in the formulations and pure form, three spectrophotometric methods: derivative of ratio spectrophotometry, first derivative and mean centering, were developed. Also, their greenness was evaluated by the Analytical Eco-Scale and the Green Analytical Procedure Index. Then, the wound healing effect of the optimized wound dressing was evaluated in rat models. Results: The optimized dressing had sufficient mechanical strength (9.45 ± 0.67 MPa), adequate flexibility (112.6 ± 3.8% EB) and suitable drug release (52.3 ± 1.4% for LV and 38.99 ± 1.6% for RVS after 12 h). The proposed methods were validated following ICH guidelines, and greenness assessment suggested their very low environmental effect. The wound healing evaluation showed a higher wound contraction percentage when RVS was combined to LV. A histopathological study confirmed marked improvement in animals treated with combined formula with lowest inflammatory infiltration and optimum epithelialization, compared to other groups. Conclusion: Study findings suggest that combined LV-RVS dressing would be a beneficial platform with potentiated wound healing capacity. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the influence of food‐grade organic acids incorporation in buckwheat starch films obtained by casting. Buckwheat starch is extracted via the alkaline methodology, and the impact of different acids and concentrations on film properties is evaluated. The films are submitted to the following characterizations: mechanical and moisture resistance properties, water vapor permeability (WVP), thermogravimetry (TG), field emission gun scanning electron microscopy (FEG‐SEM), and ATR‐FTIR (Attenuated Total Reflectance‐Fourier Transform Infrared) spectroscopy. Incorporating organic acids show film moisture reduction, WVP, and increased thermal stability. Among the organic acids tested, the films with tartaric and citric acids provide the most positive impact on the films’ mechanical and water resistance. In contrast, malic acid is demonstrated to have a less efficient crosslinking capacity. [ABSTRACT FROM AUTHOR]

Resistant starch from plantain (Macho Musa paradisiaca L.) and banana (Roatan Musa sapientum L.) varieties was chemically modified by crosslinking using epichlorohydrin (EPI). These modified starches were subjected to in vitro digestibility studies using the Englyst method to determine the content of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). The thermal stability of these crosslinked starches was evaluated by gelatinization and retrogradation analyses, and their enthalpies were determined using differential scanning calorimetry (DSC). Additionally, their functional properties were evaluated. Chemical modification with EPI significantly increased the RS content in both starch varieties compared to that in native starch. The enthalpy and gelatinization temperature decreased in the EPI-modified starches of both varieties, indicating lower thermal stability during the gelatinization process compared to that of native starch. In general, both varieties of crosslinked plantain starch had lower viscosity (0.43 Pa*s) than did native starch (0.58 Pa*s). The results indicates that this starch crosslinked with EPI constitutes an alternative for use in food for people with health problems such as high cholesterol levels or postprandial insulin concentrations. [ABSTRACT FROM AUTHOR]

Durable functionalization on polypropylene (PP) surfaces is always a key problem to besolved. Coatings with low surface energy peel off easily especially under extreme conditions, owing to their weak adhesion. In this paper, side groups of both polyhedral oligomeric silsesquioxane (POSS) and alkane are grafted to polypentafluorophenyl methacrylate (PFP), and then PP blends with these side‐group modified PFP are obtained through a melt‐blending process. It is found that POSS can result in surface segregation and provide hydrophobicity in blends. Microfibers are formed because of the orientation effect during the tensile testing, which furtherly promotes mechanical strength. Significantly, alkaneside‐groups can be entangled with PP segments, which brings about cross linking. Therefore, with crosslinking and synchronous orientation of POSS, the elongation at the break of blends is greatly increased up to 974%. The final blend demonstrates quite durable hydrophobicity under many extreme conditions, such as repeated tape peeling, ultrasonic washing, strong friction, and soaking in strong acid (pH = 1), strong alkali (pH = 14) and alcohol. The heat and UV resistance of the blend are also obviously improved. This study will develop anovel and facile strategy to endow PP with durable hydrophobicity as well as greatly enhanced mechanical properties. [ABSTRACT FROM AUTHOR]

In this work, a magnetic cross-linked chitosan-benzil/organoclay/Fe3O4 biocomposite (CHI-BZI/OC/Fe3O4) was synthesized as a bio-adsorbent for the removal of remazol brilliant blue R (RBBR) dye from aquatic environment. The adsorption factors i.e., CHI-BZI/OC/Fe3O4 dosage, pH, and time were statistically optimized using the Box-Behnken design (BBD). The highest RBBR removal efficiency of 90.9% was achieved at a CHI-BZI/OC/Fe3O4 dosage of 0.1 g/100 mL, initial solution pH of 4.0, and contact time of 20 min. The RBBR adsorption onto the CHI-BZI/OC/Fe3O4 matched the pseudo-second-order kinetic (PSO). Moreover, equilibrium study was conducted and the best fit to the adsoption expsrimantal data was described by Langmuir isotherm model. The adsorption capacity of CHI-BZI/OC/Fe3O4 for RBBR was determined to be 102.9 mg/g. This work contributes to the advancement of environmentally friendly and sustainable methods for treating dye-contaminated water, showcasing the potential of biocomposite materials as effective adsorbents in the field of water purification. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are often regarded as semi-rigid, all-carbon polymers. However, unlike conventional polymers that can form 3D networks such as hydrogels or elastomers through crosslinking in solution, CNTs have long been considered non-crosslinkable under mild conditions. This perception changed with our recent discovery of UV-defluorination-driven direct crosslinking of CNTs in solution. In this study, we further investigate the thermal stability of UV-defluorination-driven crosslinked CNTs, revealing that they are metastable and decompose more readily than either pristine or fluorinated CNTs under Raman laser irradiation. Using Raman spectroscopy under controlled laser power, we examined both single-walled and multi-walled fluorinated CNTs. The results demonstrate that UV-defluorinated CNTs exhibit reduced thermal stability compared to their pristine or untreated fluorinated counterparts. This instability is attributed to the strain on the intertube crosslinking bonds resulting from the curved carbon lattice of the linked CNTs. The metallic CNTs in the crosslinked CNT networks decompose and revert to their pristine state more readily than the semiconducting ones. The inherent instability of crosslinked CNTs leads to combustion at temperatures approximately 100 °C lower than those required for non-crosslinked fluorinated CNTs. This property positions crosslinked CNTs as promising candidates for applications where mechanically robust, lightweight materials are needed, along with feasible post-use removal options. [ABSTRACT FROM AUTHOR]

Collagen nanofibrous materials have become integral to tissue engineering due to their exceptional properties and biocompatibility. Dehydrothermal crosslinking (DHT) enhances stability and maintains structural integrity without the formation of toxic residues. The study involved the crosslinking of electrospun collagen, applying DHT with access to air and under vacuum conditions. Various DHT exposure times of up to 72 h were applied to examine the time dependance of the DHT process. The DHT crosslinked collagen was subsequently chemically crosslinked using carbodiimides. The material crosslinked in this way evinced elevated Young's modulus values and ultimate tensile strength values, a lower swelling rate and lower shrinkage ratio during crosslinking, and a higher degree of resistance to degradation than the material crosslinked solely with DHT or carbodiimides. It was shown that the crosslinking mechanism using DHT occupies different binding sites than those using chemical crosslinking. Access to air for 12 h or less did not exert a significant impact on the material properties compared to DHT under vacuum conditions. However, concerning longer exposure times, it was determined that access to air results in the deterioration of the properties of the material and that reactions take place that occupy the free bonding sites, which subsequently reduces the effectiveness of chemical crosslinking using carbodiimides. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulation (MD) technology can be used to simulate and study the physicochemical properties of polymer materials on the basis of material data obtained in traditional experiments. In this study, we use MD to construct models of crosslinked carbon nanotubes/epichlorohydrin rubber composites with different carbon nanotube diameters and study the effect of CNT tube diameter on crosslinked ECO. The results show that with the increase in CNT tube diameter, the contact area between the CNTs and rubber matrix increases, the interaction force is enhanced, the free volume fraction of rubber matrix decreases by 21.36%, the glass transition temperature increases by 6.5%, the mean square displacement decreases, the radius of gyration decreases by 3.18 Å, and the radial distribution function of the C-atom group and the H-atom group in the system gradually decreases. The binding energy between the two is elevated, which in turn verifies the enhancement of the interaction force. [ABSTRACT FROM AUTHOR]

Summary: The development of edible films, which serve as a safe alternative to synthetic polymers by utilising by‐products from the agricultural industry, has become a focus of research as they contribute to the sustainable use of resources. In the present study, quince seed gel (QSG) and whey protein concentrate (WPC) (1:1 w/w) were used as base components to develop edible films using glycerol as a plasticiser. The proteins were sonicated to denature and then the proteins were modified by cross‐linking with the enzyme transglutaminase (TGase). The thickness, moisture content, solubility, permeability and digestibility of each edible films were investigated. In addition to the morphological, mechanical, optical, thermal and structural properties, the edible films were further characterised. The thickness, moisture, water vapour and oxygen permeability and the water solubility of the films were positively influenced by the cross‐linking and the digestibility of proteins decreased with the cross‐linking. A remarkable change in the secondary structures was observed in the FTIR spectra of the films. The stronger networks and their smooth surface of crosslinked films were confirmed by AFM images. The results of this research shows that QSG/WPC films cross‐linked with TGase have potential for use in food packaging systems due to their advantages and may be an attractive alternative to synthetic materials in further studies. [ABSTRACT FROM AUTHOR]

To investigate corneal biomechanical changes after corneal cross-linking (CXL) treatments with rose bengal–green light (RB-CXL) and riboflavin-UVA (RF-CXL). A total of 60 freshly enucleated lamb eyes were obtained for this experimental study. Fifteen eyes were treated with RB-CXL using 0.1% RB solution (Group 1), 15 eyes were treated with RB-CXL using 0.2% RB solution (Group 2), 15 eyes were treated with RF-CXL using 0.1% RF solution (Group 3), and 15 eyes were used as controls (Group 4). The same treatment protocol (10-minute irradiation using a total of 5.4 J/cm2 energy) was applied to all treatment groups. To evaluate corneal biomechanical changes, the stress-strain test was used for both the treated and control corneas. The elastic modulus was calculated using the tension strain curves obtained during the test. The average elastic modulus values were calculated to be 18.9, 23.5, 22.3, and 14.1 MPa in Groups 1, 2, 3, and 4, respectively. Statistically significant differences were found between the groups (p < 0.001 for Group 1 vs. 2; p < 0.001 for Group 1 vs. 3; p < 0.001 for Group 1 vs. 4; p = 0.002 for Group 2 vs. 3; p < 0.001 for Group 2 vs. 4; and p < 0.001 for Group 3 vs. 4) In this study, the efficacy of RB-CXL treatment applied using different concentrations of RB solutions at a total energy of 5.4 J/cm2 was investigated, and 0.2% RB solution was found to have at least as much and even more effective than the RF-CXL (0.1% RF) on the corneal elasticity module. These results are encouraging for the treatment of ectatic corneas particularly below 400 μm. It is considered that the findings obtained from this study will guide future experimental and clinical studies. [ABSTRACT FROM AUTHOR]

A low viscosity tetra‐functional cyclosiloxane epoxy resins (TGTS) is synthesized via a one‐step hydrosilylation reaction and cured separately with four different aromatic diamines to explore the reaction kinetics, network development, and thermal resistance. The hardeners used are 1,3‐phenylenediamine (PDA), diethyl toluene diamine (DETDA), 4,4‐diaminodiphenylmethane (DDM), and 1,3‐bis(4‐aminophenoxy) benzene, because of their availability and aromaticity. During cure with TGTS they all display autocatalytic behavior, but when compared to a traditional organic epoxy resin, diglycidyl ether of bisphenol A (DGEBA) cured with DDM however, the rate constants are about 3 times slower and less exothermic. The DETDA hardener in particular exhibits significantly slower rates of cure when compared to the other amines, being about an order of magnitude slower compared to the PDA curative. This is attributed to higher steric hindrance, compounded by reduced miscibility. The TGTS‐DDM carbon fiber composite displays the most thermal resistance after extended exposure to 220°C, producing the least mass loss and after combustion of about 12% compared to 20% for the DGEBA cured with DDM. The results presented here, illustrate that a tetrafunctional cyclic siloxane epoxy resin, can exhibit excellent processability, evidenced by very low viscosities and long gelation times, whilst also displaying excellent thermal resistance, whether at elevated temperature, or during combustion. [ABSTRACT FROM AUTHOR]

A material capable of curing due to UV irradiation based on an alkyd oligomer and oligoorganosilsesquioxanes (OOSs) with functional thiol groups was obtained. Using microinterferometry, it was shown that the alkyd oligomer and OOS are completely compatible (mutually soluble). The resulting alkyd‐siloxane composition was cured under the action of UV irradiation due to reaction between double bonds of alkyd oligomer and thiol‐groups of silsesquioxane oligomer. The curing reaction takes 5 min with formation of coating, containing 99% of gel fraction, which is in 30 times faster in comparison with the classical method of alkyd curing in the presence of siccatives. The hydrophobicity of alkyd‐siloxane coatings also increases and varies depending on the content of OOS. The introduction of 50% OOS into the alkyd oligomer makes it possible to increase the water contact angle by 10° relative to the coating based on pure alkyd. A similar dependence is observed when studying the thermal stability of coatings. Thus, even with the introduction of 10% OOS into alkyd oligomer, the temperature at which a loss of 50% of mass occurs increases by 24°C relative to coatings based on a pure alkyd oligomer. [ABSTRACT FROM AUTHOR]

Diglycidyl ether of bisphenol A (DGEBA), a key intermediate for epoxy resins, provides strong adhesion, processability and the resulting thermoset boasts high cross linking density. However, the inherent brittleness and susceptibility to cracking restrict its advanced applications. To overcome these drawbacks, CO2 fixed cyclic carbonate from castor oil (CCO) was synthesized from epoxidised castor oil (ECO) and used in varying quantities as a toughening agent for amine cured DGEBA. Different amines have been utilized to cure the epoxy and to study the structure–property relationship by fixing the amount of CCO. The inclusion of 10% CCO resulted in improvement in the tensile strength, storage modulus, flexural modulus, and impact strength of the epoxy‐urethane hybrid. Moreover, the epoxy‐urethane networks had reduced cross linking density imparted by the fatty acid units of CCO and the presence of unreacted carbonate groups facilitated molecular movement, thereby contributing to energy dissipation during the deformation process. Further incorporation of the CCO lowers the mechanical properties of the hybrids due to a reduction in cross linking density. Trimethylolpropane tris[poly(propyleneglycol)amine terminated] ether cured system exhibited the highest thermal stability compared to hexamethylene diamine, isophorone diamine, and 4,7,10‐trioxa‐1,13 tridecanediamine. The Tg decreased as the CCO content increased, while the water contact angle increased. [ABSTRACT FROM AUTHOR]

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Waterborne polyurethane (WPU) has excellent performance because of its special soft and hard segments in polymer chains, but the relatively high cost, poor water vapor permeability, and inferior biocompatibility limit its application. The introduction of biomass materials can improve the performance of WPU. Keratin belongs to natural macro-molecule compounds which contain numerous peptide bonds and hydrophilic groups. It can make up for the shortcomings of WPU materials. In this study, keratin was extracted from the recycled cattle hair waste, and then it was chemically bonded with isocyanates, polyols, and other raw materials to prepare a keratin-modified WPU film which has excellent performance. First, polytetramethylene ether glycol (PTMEG) was reacted with 4.4-dicyclohexylmethane diisocyanate (HMDI) to form a prepolymer, then it was reacted with dimethylol propionic acid (DMPA), neopentyl glycol (NPG) and trimethylolpropane (TMP). The addition of keratin was in the emulsification process, and the structure of keratin-modified WPU was investigated. TG analysis results showed that the addition of keratin can improve the thermal stability of the WPU film with a higher residual carbon content at 600°C. The DMA analysis showed that the mechanical properties of the modified WPU film with a certain amount of keratin added (≤ 0.1%) were significantly improved. The yellowing resistance test showed that the addition of an appropriate amount (≤ 0.1%) of keratin can increase its stability to light, but the addition of an excessive amount of protein (≥ 0.2%) will result in a decrease in the yellowing resistance of the WPU film. [ABSTRACT FROM AUTHOR]

Fatigue crack propagation resistance and high-cycle S–N fatigue life of cortical bone allograft tissue are both negatively impacted in a radiation dose-dependent manner from 0 to 25 kGy. The standard radiation sterilization dose of 25–35 kGy has been shown to induce cleavage of collagen molecules into smaller peptides and accumulation of stable crosslinks within the collagen matrix, suggesting that these mechanisms may influence radiation-induced losses in cyclic fracture resistance. The objective of this study was to determine the radiation dose-dependency of collagen chain fragmentation and crosslink accumulation within the dose range of 0–25 kGy. Previously, cortical bone compact tension specimens from two donor femoral pairs were divided into four treatment groups (0 kGy, 10 kGy, 17.5 kGy, and 25 kGy) and underwent cyclic loading fatigue crack propagation testing. Following fatigue testing, collagen was isolated from one compact tension specimen in each treatment group from both donors. Radiation-induced collagen chain fragmentation was assessed using SDS-PAGE (n = 5), and accumulation of pentosidine, pyridinoline, and non-specific advanced glycation end products were assessed using a fluorometric assay (n = 4). Collagen chain fragmentation increased progressively in a dose-dependent manner (p < 0.001). Crosslink accumulation at all radiation dose levels increased relative to the 0 kGy control but did not demonstrate dose-dependency (p < 0.001). Taken together with our previous findings on fatigue crack propagation behavior, these data suggest that while collagen crosslink accumulation may contribute to reduced notched fatigue behavior with irradiation, dose-dependent losses in fatigue crack propagation resistance are mainly influenced by radiation-induced chain fragmentation. [ABSTRACT FROM AUTHOR]

Flexible sensors can measure various stimuli owing to their exceptional flexibility, stretchability, and electrical properties. However, the integration of multiple stimuli into a single sensor for measurement is challenging. To address this issue, the sensor developed in this study utilizes the natural biopolymers sodium alginate and carboxymethyl cellulose to construct a dual interpenetrating network, This results in a flexible porous sponge that exhibits a dual-modal response to strain and magnetic stimulation. The dual-mode flexible sensor achieved a maximum tensile strength of 429 kPa and elongation at break of 24.7%. It also exhibited rapid response times and reliable stability under both strain and magnetic stimuli. The porous foam sensor is intended for use as a wearable electronic device for monitoring joint movements of the body. It provides a swift and stable sensing response to mechanical stimuli arising from joint activities, such as stretching, compression, and bending. Furthermore, the sensor generates opposing response signals to strain and magnetic stimulation, enabling real-time decoupling of different stimuli. This study employed a simple and environmentally friendly manufacturing method for the dual-modal flexible sensor. Because of its remarkable performance, it has significant potential for application in smart wearable electronics and artificial electroskins. [ABSTRACT FROM AUTHOR]

The specific detection of serum IgE antibodies specific to allergens (sIgE Abs) that can crosslink the plural high-affinity IgE receptor (FcεRIα) molecules on the surface of mast cells or basophils with a multivalent allergen can reduce the false-positive diagnoses observed in chemiluminescent and fluorescence enzyme immunoassays for type-I allergic patients. In this study, we detected sIgE Abs to the egg-allergen ovalbumin (OVA) and the wheat-allergen gluten in the sera of rats sensitized with each allergen using an amplified luminescence proximity homogeneous assay by crosslinking (AlphaCL). OVA and gluten were reacted with each sIgE Ab in the sera. Then, acceptor and donor beads labeled with the human FcεRIα were added to the reacted solution. The luminescence intensity for anti-OVA IgE Abs in the sera with the removal of IgG Abs was observed in five of seven (71.4%) of the sensitized rats, whereas no signals were observed in any of the unsensitized rats. The AlphaCL could also detect anti-gluten sIgE Abs in the sera of sensitized rats, but not of unsensitized rats. In conclusion, we successfully detected sIgE Abs in the sera of rats sensitized to two allergens using the AlphaCL. This detection method has the potential to be used as a new diagnostic tool for type-I allergic patients. [ABSTRACT FROM AUTHOR]

Although noncovalent interactions and covalent reactions between phenolic compounds and proteins have been investigated across diverse scientific disciplines, a comprehensive understanding and identification of their products remain elusive. This review will initially outline the chemical framework and, subsequently, delve into unresolved or debated chemical and functional food‐related implications, as well as forthcoming challenges in this topic. The primary objective is to elucidate the multiple aspects of protein–phenolic interactions and reactions, along with the underlying overwhelming dynamics and possibilities of follow‐up reactions and potential crosslinking between proteins and phenolic compounds. The resulting products are challenging to identify and characterize analytically, as interactions and reactions occur concurrently, mutually influencing each other. Moreover, they are being modulated by various conditions such as the reaction parameters and, obviously, the chemical structure. Additionally, this review delineates the resulting discrepancies and challenges of properties and attributes such as color, taste, foaming, emulsion and gel formation, as well as effects on protein digestibility and allergenicity. Ultimately, this review is an opinion paper of a group of experts, dealing with these challenges for quite a while and aiming at equipping researchers with a critical and systematic approach to address current research gaps concerning protein–phenolic interactions and reactions. [ABSTRACT FROM AUTHOR]

AbstractLocalized oral drug delivery offers several advantages for treating various disease conditions. However, drug retention at the disease site within the oral cavity is indeed a significant challenge due to the dynamic oral environment. The present study aimed to develop a mucoadhesive inner layer for a three-layer mucoadhesive bandage suitable for localized oral drug delivery. using gellan gum (GG) biopolymer. Gellan gum (GG) was modified using L-cysteine moieties via carbodiimide chemistry. Subsequently, gellan gum solution at different extents of thiolation was ionically cross-linked using aluminum ammonium sulfate. Thiolated gellan gum films of uniform thickness were prepared using a solvent casting method. The thickness of bare gellan gum film was 0.035 ± 0.0043 mm, whereas the thiolated gellan gum films, GG 1S and GG 2S showed a thickness of 0.0191 ± 0.0011 mm and 0.0188 ± 0.0004 mm respectively. A high work of adhesion was noted for thiolated gellan gum (GG 2S) with a value of 10 N.mm while using porcine buccal mucosa. An average tensile strength of 48.2 ± 2.46 MPa was measured for thiolated gellan gum films irrespective of the extent of thiolation. The high work of adhesion, favorable cytocompatibility, desirable mechanical properties, and free swell capacity in saline confirmed the suitability of ionically cross-linked thiolated gellan gum films as an inner mucoadhesive layer for the mucoadhesive bandage. [ABSTRACT FROM AUTHOR]

Polymeric foamed materials are among the most widely utilized technologies for oil spill accidents and releases of oil‐contaminated wastewater oil due to their porosity to absorb and separate oil/water effectively. However, a major limitation of traditional polymeric foams is their reliance on an ad/absorption mechanism as the sole method of oil capture, leading to potential oil leakage once their saturation point is exceeded. Tri‐block polymer styrene‐ethylene‐butylene‐styrene (SEBS) is a fascinating absorbent material that can bypass this limitation by both capturing oil and providing a sealing mechanism via gelation to prevent oil leakage due to its unique chemical structure. SEBS foams are produced via simultaneous crosslinking and foaming that results in an impressive expansion ratio of up to 15.2 with over 93% porosity. Most importantly, the SEBS foams show great potential as oil absorbents in spill remediation, demonstrating rapid and efficient oil absorption coupled with superhydrophobic properties. Moreover, the unique interaction between the oil and SEBS enables the formation of a physical gel, acting as an effective barrier against oil leakage. These findings indicate the potential for commercializing SEBS foam as a viable option for geotextiles to mitigate oil spill concerns from infrastructures. [ABSTRACT FROM AUTHOR]

To synthesize an effective and versatile nano-platform serving as a promising carrier for controlled drug delivery, visible-light-induced diselenide-crosslinked polyurethane micelles were designed and prepared for ROS-triggered on-demand doxorubicin (DOX) release. A rationally designed amphiphilic block copolymer, poly(ethylene glycol)-b-poly(diselenolane diol-co-isophorone diisocyanate)-b-poly(ethylene glycol) (PEG-b-PUSe-b-PEG), which incorporates dangling diselenolane groups within the hydrophobic PU segments, was initially synthesized through the polycondensation reaction. In aqueous media, this type of amphiphilic block copolymer can self-assemble into micellar aggregates and encapsulate DOX within the micellar core, forming DOX-loaded micelles that are subsequently in situ core-crosslinked by diselenides via a visible-light-triggered metathesis reaction of Se-Se bonds. Compared with the non-crosslinked micelles (NCLMs), the as-prepared diselenide-crosslinked micelles (CLMs) exhibited a smaller particle size and improved colloidal stability. In vitro release studies have demonstrated suppressed drug release behavior for CLMs in physiological conditions, as compared to the NCLMs, whereas a burst release of DOX occurred upon exposure to an oxidation environment. Moreover, MTT assay results have revealed that the crosslinked polyurethane micelles displayed no significant cytotoxicity towards HeLa cells. Cellular uptake analyses have suggested the effective internalization of DOX-loaded crosslinked micelles and DOX release within cancer cells. These findings suggest that this kind of ROS-triggered reversibly crosslinked polyurethane micelles hold significant potential as a ROS-responsive drug delivery system. [ABSTRACT FROM AUTHOR]

Different dyes are discharged into water streams, causing significant pollution to the entire ecosystem. The present work deals with the removal of acid red 2 dye (methyl red—as an anionic dye) by green sorbents based on chitosan derivatization. In this regard, two classes of chitosan derivatives—a total of six—were prepared by gamma irradiation at 30 kGy. The first group (group A) constitutes a crosslinked chitosan/polyacrylamide/aluminum oxide with different feed ratios, while the second group, identified as group B, is composed of crosslinked carboxymethyl chitosan/polyacrylamide/aluminum oxide with different ratios. Glycerol was added to soften the resultant hydrogels. The products were characterized by different tools, including FTIR for confirming the chemical modification, TGA for investigating their thermal properties, and XRD for verifying their crystalline structure. The morphology of the prepared derivatives was studied through SEM, while their topography before and after dye adsorption was monitored via the AFM. The removal efficiencies of the prepared sorbents were verified at different operation conditions, such as pH, temperature, adsorbent dose, initial concentration of dye solutions, and contact time. The data revealed that the optimum conditions for maximum dye uptake were as follows: pH 4, contact time 120 min, 0.1-g sorbent dose, and 50-ppm dye concentration. Additionally, the prepared sorbents demonstrated potent adsorption capacity and removal efficiency. It was found that the elements of the second group displayed higher performance than their counterparts. The data showed also that the adsorption process best fits with the Freundlich model and obeyed pseudo-first-order kinetic isotherm. In addition, the synthesized composites showed observable antibacterial potency toward E. coli as a Gram-negative bacterium and S. aureus as a Gram-positive bacterium. [ABSTRACT FROM AUTHOR]

Purpose: To analyse the temperature of the corneal surface in keratoconus during corneal customized crosslinking (CXL) with a preserved epithelium (epi‐on) under oxygen flow, and epi‐off CXL in room air, and to assess the effect of pre‐heating the oxygen. Methods: This masked, intra‐individual comparing randomized study included 14 participants with bilateral progressive keratoconus treated with bilateral CXL: one eye with epi‐on CXL under a flow of 2.5 L/min oxygen; the fellow eye with epi‐off CXL in room air. In a second setting involving 12 healthy participants, room‐tempered oxygen was flushed over one eye and oxygen pre‐heated to 37°C over the fellow eye. The corneal surface temperature was assessed with infrared photography. Results: A reduction in corneal surface temperature was seen from the pre‐treatment application of topical riboflavin in the epi‐off group (−1.1 ± 1.0°C, p < 0.001). The temperature increased during the first half of the CXL treatment in both groups (+0.7 ± 1.2°C, p = 0.041 for epi‐on; +0.7 ± 0.9°C, p = 0.023 for epi‐off CXL, respectively). In epi‐on CXL an overall temperature increase was seen during the treatment (+0.8 ± 1.2°C, p = 0.016). In the second setting, pre‐heating the oxygen rendered a surface temperature increase of +1.8 ± 0.2°C (p < 0.001). Conclusion: In epi‐off CXL, the application of topical room‐tempered riboflavin decreases the corneal surface temperature, likely due to increased evaporation. A slight temperature increase is seen during CXL with both epi‐on and epi‐off CXL, albeit far below the corneal safety limit. The corneal temperature can, however, be increased by applying pre‐heated oxygen, a possible approach to modify or augment the treatment effect in CXL. [ABSTRACT FROM AUTHOR]

Crumb rubber (CR) that had been used in an outdoor football stadium in the U.S.A. for over 10 years was sampled, analysed and compared to samples taken from an on-site, covered excess CR stockpile and from fresh CR that could be used to replace the used CR. These tests were accomplished to determine if the original CR properties had changed significantly, from new/un-used CR, which could have safety and performance implications if continued use of this CR was planned. A series of analytical and mechanical tests were performed to determine degradation effects over time that included Fourier-transform infrared spectroscopy (FTIR), solvent swell tests, differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), X-ray emission spectroscopy (XES), vertical impact, hardness and bulk density. Results inferred compositional differences and mechanical property changes between all three CR samples, with indications that the older CR was demonstrating concurrent increased crosslinking and molecular scissioning, with subsequent loss in resilience. The FTIR results indicated various polymer types present that originated from recycled automobile tyres as well as evidence of oxidation in the used CR. The DSC exhibited lower thermal enthalpy and higher glass transition temperatures confirming compositional changes in older samples. Both vertical impact and hardness tests showed a significant increase in hardness and lower resilience in the used CR. A significant decrease in average size in the used CR was revealed through sieving and microscopy, which indicated mechanical wear. Bulk density measurements of un-sieved used and stockpile CR showed a substantial increase in bulk density for the used samples. The fresh, new potential replacement CR appears to originate from a different supplier than the CR originally used on the sports surface (and accompanying stockpile CR) and possessed much higher resilience than the used CR. [ABSTRACT FROM AUTHOR]

In the context of advanced nanomaterials research, nanogels (NGs) have recently gained broad attention for their versatility and promising biomedical applications. To date, a significant number of NGs have been developed to meet the growing demands in various fields of biomedical research. Summarizing preparation methods, physicochemical and biological properties, and recent applications of NGs may be useful to help explore new directions for their development. This article presents a comprehensive overview of the latest NG synthesis methodologies, highlighting advances in formulation with different types of hydrophilic or amphiphilic polymers. It also underlines recent biomedical applications of NGs in drug delivery and imaging, with a short section dedicated to biosafety considerations of these innovative nanomaterials. In conclusion, this article summarizes recent innovations in NG synthesis and their numerous applications, highlighting their considerable potential in the biomedical field. [ABSTRACT FROM AUTHOR]

This study investigates the crosslinking dynamics and swelling properties of pH-responsive poly(ethylene glycol) (PEG)/poly(acrylic acid) (PAA) interpenetrating polymer network (IPN) hydrogels. These hydrogels feature denser crosslinked networks compared to PEG single network (SN) hydrogels. Fabrication involved a two-step UV curing process: First, forming PEG-SN hydrogels using poly(ethylene glycol) diacrylate (PEGDA) through UV-induced free radical polymerization and crosslinking reactions, then immersing them in PAA solutions with two different molar ratios of acrylic acid (AA) monomer and poly(ethylene glycol) dimethacrylate (PEGDMA) crosslinker. A subsequent UV curing step created PAA networks within the pre-fabricated PEG hydrogels. The incorporation of AA with ionizable functional groups imparted pH sensitivity to the hydrogels, allowing the swelling ratio to respond to environmental pH changes. Rheological analysis showed that PEG/PAA IPN hydrogels had a higher storage modulus (G′) than PEG-SN hydrogels, with PEG/PAA-IPN5 exhibiting the highest modulus. Thermal analysis via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated increased thermal stability for PEG/PAA-IPN5 compared to PEG/PAA-IPN1, due to higher crosslinking density from increased PEGDMA content. Consistent with the storage modulus trend, PEG/PAA-IPN hydrogels demonstrated superior mechanical properties compared to PEG-SN hydrogels. The tighter network structure led to reduced water uptake and a higher gel modulus in swollen IPN hydrogels, attributed to the increased density of active network strands. Below the pKa (4.3) of acrylic acid, hydrogen bonds between PEG and PAA chains caused the IPN hydrogels to contract. Above the pKa, ionization of PAA chains induced electrostatic repulsion and osmotic forces, increasing water absorption. Adjusting the crosslinking density of the PAA network enabled fine-tuning of the IPN hydrogels' properties, allowing comprehensive comparison of single network and IPN characteristics. [ABSTRACT FROM AUTHOR]