Search

Drosophila glue, a bioadhesive produced by fly larvae to attach themselves to a substrate for several days, has recently gained attention for its peculiar adhesive and mechanical properties. Although Drosophila glue production was described more than 50 years ago, a general survey of the adhesive and mechanical properties of this proteinaceous gel across Drosophila species is lacking. To measure adhesion, we present here a protocol that is robust to variations in protocol parameters, pupal age and calculation methods. We find that the glue, which covers the entire pupal surface, increases the animal rigidity and plasticity when bound to a glass slide. Our survey of pupal adhesion in 25 Drosophilidae species reveals a wide range of phenotypes, from species that produce no or little glue and adhere little, to species that produce high amounts of glue and adhere strongly. One species, D. hydei, stands out from the rest and emerges as a promising model for the development of future bioadhesives, as it has the highest detachment force per glue area and produces relatively large amounts of glue relative to its size. We also observe that species that invest more in glue tend to live in more windy and less rainy climates, suggesting that differences in pupal adhesion properties across species are shaped by ecological factors. Our present survey provides a basis for future biomimetic studies based on Drosophila glue. [ABSTRACT FROM AUTHOR]

Biomaterials that integrate multiple functionalities, mimic the extracellular matrix (ECM) microenvironment to support cellular growth, and adhere robustly to damaged tissues are highly needed to advance tissue engineering. Protein‐based biomaterials are promising due to their inherent biocompatibility, biomimicry, biodegradation, and cell‐supportive properties. Herein, by leveraging the unique ability of dithiolanes to generate on‐demand in situ thiols, a new class of dithiolane‐modified, protein‐based biomaterial that combines unique, seemingly opposing functions for tissue engineering is developed. Dithiolane‐modified gelatin, a model protein used herein, enabled photoinitiator‐free photo‐crosslinking to form multi‐functional gelatin‐dithiolane (GelDT) hydrogels, which displayed exceptional long‐term stability in cell culture media (>28 days) to support the growth of both surface‐seeded and encapsulated cells. GelDT hydrogels allowed pre‐gelation tuning of biomechanical properties and biodegradation via introducing physical crosslinks, and post‐gelation tuning of matrix stress‐relaxation rate, via responding to exogenous thiols, independently of other parameters. Furthermore, GelDT enabled covalent immobilization of bio‐active molecules, glutathione‐responsive drug release, supported efficient 3D bioprinting due to its shear‐thinning ability, and demonstrated robust tissue adhesion in various contexts (bare skin, ex‐vivo, in‐vivo) due to covalent disulfide coupling with endogenous tissue thiols. Together, this study presents a novel multi‐responsive and multi‐functional protein‐based biomaterial, anticipated to advance tissue engineering and regeneration. [ABSTRACT FROM AUTHOR]

AbstractPolymer-based drug delivery systems are pivotal in advancing the precision and efficacy of modern therapeutics. Among the key factors influencing these systems, surface energy and wettability are crucial in determining their interaction with biological tissues and drug release behavior. Surface energy, which governs the adhesive properties of the polymers, plays a significant role in bioadhesion—a critical aspect for drug delivery routes that require prolonged contact with biological surfaces, such as mucosal membranes. Wettability, the extent to which a polymer surface can be wetted by biological fluids, influences both drug loading efficiency and release kinetics. Hydrophilic polymers, characterized by high wettability, typically facilitate rapid drug release, whereas hydrophobic polymers, with low wettability, offer controlled, prolonged release profiles. Additionally, the balance between hydrophilicity and hydrophobicity is essential for optimizing drug-polymer interactions, particularly in systems designed for sustained or targeted drug delivery. Advances in surface modification techniques have enabled precise control over these parameters, allowing for the customization of polymers to meet specific therapeutic requirements. This review discusses the interplay between surface energy, wettability, and drug delivery performance, highlighting how these properties have been manipulated to enhance bioadhesion, drug retention, and release profiles. The review also addresses the challenges in designing polymer wettability, such as maintaining stability, scalability, and regulatory compliance. Finally, it explores emerging trends, including stimuli-responsive polymers and nanotechnology integration, which hold promise for the next generation of drug delivery systems that are more efficient, targeted, and patient-specific, than current systems. [ABSTRACT FROM AUTHOR]

Abstract Drosophila glue, a bioadhesive produced by fly larvae to attach themselves to a substrate for several days, has recently gained attention for its peculiar adhesive and mechanical properties. Although Drosophila glue production was described more than 50 years ago, a general survey of the adhesive and mechanical properties of this proteinaceous gel across Drosophila species is lacking. To measure adhesion, we present here a protocol that is robust to variations in protocol parameters, pupal age and calculation methods. We find that the glue, which covers the entire pupal surface, increases the animal rigidity and plasticity when bound to a glass slide. Our survey of pupal adhesion in 25 Drosophilidae species reveals a wide range of phenotypes, from species that produce no or little glue and adhere little, to species that produce high amounts of glue and adhere strongly. One species, D. hydei, stands out from the rest and emerges as a promising model for the development of future bioadhesives, as it has the highest detachment force per glue area and produces relatively large amounts of glue relative to its size. We also observe that species that invest more in glue tend to live in more windy and less rainy climates, suggesting that differences in pupal adhesion properties across species are shaped by ecological factors. Our present survey provides a basis for future biomimetic studies based on Drosophila glue.

Although bio‐adhesives have achieved many progresses, creating robust bio‐glues that could withstand the complex physiological microenvironment remains a significant challenge such as limited bioadhesion strength and stability, as well as slow adhesion speed caused by pH, enzymes, salt, and bacteria. Herein, a series of strong bio‐glues are successfully fabricated using a polyphenol–acrylamide–ruthenium crosslinking (PARC) reaction under visible light irradiation, involving acrylamides radical polymerization, polyphenols (extracts) coupling reaction, and ruthenium‐mediated photochemistry. The resulting bio‐glues underwent rapid sol–gel transition and exhibited adhesive properties within a short of time (≈5 s), which could quickly bond to various bio‐tissues. Moreover, these bioadhesives demonstrate high adhesion strength and stability with mucosal tissue in the oral environment, effectively promoting rat and pig oral mucosal wound healing. It is anticipated that this class of visible light‐responsive polyphenolic bio‐glues could serve as a robust tool for addressing oral mucosal defects in the clinic, offering a promising alternative to traditional treatments for oral mucosal disorders. [ABSTRACT FROM AUTHOR]

We report a biocompatible hydrogel dressing based on sodium alginate-grafted poly(N-vinylcaprolactam) prepared by encapsulation of Rifampicin as an antimicrobial drug and stabilizing the matrix through the repeated freeze–thawing method. The hydrogel structure and polymer-drug compatibility were confirmed by FTIR, and a series of hydrogen-bond-based interactions between alginate and Rifampicin were identified. A concentration of 0.69% Rifampicin was found in the polymeric matrix using HPLC analysis and spectrophotometric UV–Vis methods. The hydrogel's morphology was evaluated by scanning electron microscopy, and various sizes and shapes of pores, ranging from almost spherical geometries to irregular ones, with a smooth surface of the pore walls and high interconnectivity in the presence of the drug, were identified. The hydrogels are bioadhesive, and the adhesion strength increased after Rifampicin was encapsulated into the polymeric matrix, which suggests that these compositions are suitable for wound dressings. Antimicrobial activity against S. aureus and MRSA, with an increased effect in the presence of the drug, was also found in the newly prepared hydrogels. In vitro biological evaluation demonstrated the cytocompatibility of the hydrogels and their ability to stimulate cell multiplication and mutual cell communication. The in vitro scratch assay demonstrated the drug-loaded alginate-grafted poly(N-vinylcaprolactam) hydrogel's ability to stimulate cell migration and wound closure. All of these results suggest that the prepared hydrogels can be used as antimicrobial materials for wound healing and care applications. [ABSTRACT FROM AUTHOR]

3D bioprinting techniques have enabled the fabrication of irregular large‐sized tissue engineering scaffolds. However, complicated customized designs increase the medical burden. Meanwhile, the integrated printing process hinders the cellular uniform distribution and local angiogenesis. A novel approach is introduced to the construction of sizable tissue engineering grafts by employing hydrogel 3D printing for modular bioadhesion assembly, and a poly (ethylene glycol) diacrylate (PEGDA)‐gelatin‐dopamine (PGD) hydrogel, photosensitive and adhesive, enabling fine microcage module fabrication via DLP 3D printing is developed. The PGD hydrogel printed micocages are flexible, allowing various shapes and cell/tissue fillings for repairing diverse irregular tissue defects. In vivo experiments demonstrate robust vascularization and superior graft survival in nude mice. This assembly strategy based on scalable 3D printed hydrogel microcage module could simplify the construction of tissue with large volume and complex components, offering promise for diverse large tissue defect repairs. [ABSTRACT FROM AUTHOR]

In transdermal applications of nonsteroidal anti-inflammatory drugs, the rheological and mechanical properties of the dosage form affect the performance of the drug. The aim of this study to develop emulgel and nanostructured lipid carrier NLC-based gel formulations containing ibuprofen, evaluate their mechanical properties, bioadhesive value and ex-vivo rabbit skin permeability. All formulations showed non-Newtonian pseudoplastic behavior and their viscosity values are suitable for topical application. The particle size of the nanostructured lipid carrier system was found to be 468 ± 21 nm, and the encapsulation efficiency was 95.58 ± 0.41%. According to the index of viscosity, consistency, firmness, and cohesiveness values obtained as a result of the back extrusion study, E2 formulation was found to be more suitable for transdermal application. The firmness and work of shear values of the E2 formulation, which has the highest viscosity value, were also found to be the highest and it was chosen as the most suitable formulation in terms of the spreadability test. The work of bioadhesion values of NLC-based gel and IBU-loaded NLC-based gel were found as 0.226 ± 0.028 and 0.181 ± 0.006 mJ/cm2 respectively. The percentages of IBU that penetrated through rabbit skin from the Ibuactive-Cream and the E2 were 87.4 ± 2.11% and 93.4 ± 2.72% after 24 h, respectively. When the penetration of ibuprofen through the skin was evaluated, it was found that the E2 formulation increased penetration due to its lipid and nanoparticle structure. As a result of these findings, it can be said that the NLC-based gel formulation will increase the therapeutic efficacy and will be a good alternative transdermal formulation. [ABSTRACT FROM AUTHOR]

Xerosis is one of the common dermatological problems. Preparations recommended for daily care of the dry skin are emollients. Emollient preparations demonstrate a moisturizing effect, they soften and smoothen the skin, keep water in the epidermis, supplement lipids of skin upper layers and protect from external harmful agents. The purpose of this study was to develop and characterize emollients containing natural emulsifier Olivem 1000 as topical delivery systems for urea or sodium hialuronate. Physicochemical and mechanical properties of designed formulations were evaluated. Moreover, ex vivo adhesion study on the hairless mice skin as a model of adhesive layer was carried out and in vivo preliminary assessment of transepidermal water loss (TEWL) was performed. Prepared emollient formulations were characterized by smooth consistency, they were easily spreadable on the skin surface and showed no phase separation. Formulations containing xanthan gum as a thickening agent were characterized by higher viscosity, hardness, cohesiveness and adhesiveness values. Prepared emollients showed thixotropic properties and they were classified as non-Newtonian shear thinning systems. All prepared emollients demonstrated bioadhesive properties. The analysis of TEWL showed that the greatest decrease in the TEWL value was noted in the case of emollient containing sodium hyaluronate which was applied to the person with the skin described as “the skin in a very poor condition”. The results of the conducted research indicate that developed emollients containing natural emulsifier Olivem 1000 seem to be a promising form of care preparations for topical use in case of chronic dryness of the skin.

The aim of this study is to understand the effect of the food product's, even in trace amounts, in the biofilm formation potential of Escherichia coli and Staphylococcus aureus. Bacterial adhesion was tested using three different food media, in which bacterial cells were adapted before determining how this would affect their adhesion score and biofilm formation potential: sterilized milk, mineral water, and pasteurized commercial orange juice. After characterization of the bacteria and the adhesion support by the contact angle, the adhesion score obtained by the theoretical mathematical model XDLVO developed by van Oss was compared to that obtained by the experimental approach, in order to examine the role of non-specific (thermodynamic) and specific (biological) interactions in adhesion. Changes in the membrane composition of bacteria, as a function of acclimation conditions, were evaluated by infrared spectroscopy. Results reveal variability in the spectral region between 900 and 1200 cm-1 specific to capsular polysaccharides (CPS) or lipopolysaccharides (LPS), and also in the range between 2800 and 3000 cm-1 characteristic of membrane lipids and phospholipids. Biofilm formation by S. aureus and E. coli was affected by commercial UHT milk. This led to increased hydrophobicity and total adhesion energy within the environment of these strains. However, no correlation was observed between the adhesion scores obtained through experimental and theoretical approaches. This underscores the necessity of considering the specific characteristics of individual food products in understanding the phenomenon of biofilm formation. Understanding, the mechanism, the variations in bacterial surface characteristics, and the conditions that favor or disadvantage the formation of biofilms, may have important implications, in the development of preventive and curative strategies, to control of food-borne infections. [ABSTRACT FROM AUTHOR]

Drug administration by oral delivery is the preferred route, regardless of some remaining challenges, such as short resident time and toxicity issues. One strategy to overcome these barriers is utilizing mucoadhesive vectors that can increase intestinal resident time and systemic uptake. In this study, biomimetic nanoparticles (NPs) were produced from 14 types of edible algae and evaluated for usage as oral DDSs by measuring their size, surface charge, morphology, encapsulation efficiency, mucoadhesion force, and cellular uptake into Caco-2 cells. The NPs composed of algal materials (aNPs) exhibited a spherical morphology with a size range of 126–606 nm and a surface charge of −9 to −38 mV. The mucoadhesive forces tested ex vivo against mice, pigs, and sheep intestines revealed significant variation between algae and animal models. Notably, Arthospira platensis (i.e., Spirulina) NPs (126 ± 2 nm, −38 ± 3 mV) consistently exhibited the highest mucoadhesive forces (up to 3127 ± 272 µN/mm²). Moreover, a correlation was found between high mucoadhesive force and high cellular uptake into Caco-2 cells, further supporting the potential of aNPs by indicating their ability to facilitate drug absorption into the human intestinal epithelium. The results presented herein serve as a proof of concept for the possibility of aNPs as oral drug delivery vehicles. [ABSTRACT FROM AUTHOR]

Bioactive and biocompatible BC/AgNP composite films were synthesized by loading silver nanoparticle (AgNP) into bacterial cellulose (BC) fibrils. Physicochemical analyses (FTIR, TGA-DSC, SEM-EDS, TEM, XRD) and mechanical tests were performed on the synthesized BC fibril and BC/AgNP composite films. Young's Modulus, Tensile strength, Elongation at break, Compressive strength and Stiffness of (45% moisture) BC/AgNP composite films were found to be 253.2 ± 2.01 MPa, 13.7 ± 1.40 MPa, 21.4 ± 1.67%, 47.17 ± 8.98 MPa, 1.05 ± 2.32 GPa and 519.88 ± 81.51 (Units), respectively. Moreover, the high-water retention capacity of BC fibril structures was supported by the contact angles and swelling profiles observed in BC/AgNP composite structures. Further, the bioadhesion performance of BC/AgNP composite films was evaluated ex vivo on chicken skin and it was observed that the presence of AgNP played an active role in the adhesion behavior of the composite films. It was also observed that the synthesized BC/AgNP composite films exhibited bactericidal behavior against pathogens (Staphylococcus aureus and Pseudomonas aeruginosa) and had a high bactericidal effect. Biocompatibility tests of the composite films were evaluated by using L929 mouse fibroblast cells. The cell nucleus wall staining (Mitored and Dio6) and fluorescence visualization studies were performed to investigate the biocompatibility behavior of BC/AgNP composite films. The results showed that BC/AgNP composite films did not any cytotoxic effect and allowed epidermal cells to adhere and grow. Overall, obtained results showed that the synthesized biocompatible BC/AgNP composite films are suitable to be used as wound dressings in tissue engineering applications and may be used as a bioactive material that can reduce inflammation in skin barriers and promote wound healing. [Display omitted] • Bacterial cellulose was produced by bacteria (Gluconacetobacter hansenii , ATCC 23769) incubated under a static condition. • SEM-EDS, FTIR, TGA and XRD showed the incorporation of silver nanoparticles. • Bacterial cellulose-silver nanoparticle composite film exhibited bioadhesive behaviour. • Bacterial cellulose-silver nanoparticle composite film exhibited good antibacterial properties. • Bacterial cellulose-silver nanoparticle composite film did not exhibit cytotoxic behaviour. [ABSTRACT FROM AUTHOR]

Known as the degenerative disease of the knee with the highest prevalence, knee osteoarthritis (KOA) is characterized by a gradual destructive mechanism that, in severe cases, can provoke the need for total knee substitution. As the disease progresses, various enzymatic, immunological, and inflammatory processes abnormally degrade hyaluronic acid (HA), SF's main component, and affect the concentrations of specific proteins, with the final results seriously endangering synovial fluid (SF)'s rheological and tribological features and characteristics. No effective treatments have been found to stop the progression of KOA, but the injection of HA-based viscoelastic gels has been considered (alone or combined with physiotherapy (PT)) as an alternative to symptomatic therapies. In order to evaluate the effect of viscosupplementation and PT on the characteristics of SF, SF aspirated from groups treated for KOA (HA Kombihylan® and groups that received Kombihylan® and complex PT) was analyzed and compared from analytical, spectrophotometrical, and rheological perspectives. In the patients treated with PT, the SF extracted 6 weeks after viscosupplementation had a superior elastic modulus (G′) and viscous moduli (G″), as well as a homogeneous distribution of proteins and polysaccharides. The viscosupplementation fluid improved the bioadhesive properties of the SF, and the use of the viscosupplementation fluid in conjunction with PT was found to be favorable for the distribution of macromolecules and phospholipids, contributing to the lubrication process and the treatment of OA-affected joints. [ABSTRACT FROM AUTHOR]

Repairing Achilles tendon has emerged as a long-standing challenge in the orthopaedic surgeries. Although suture is the gold standard for re-attaching and repairing the fractured Achilles tendons in clinical surgeries, it is still subjected to numerous adverse side-effects, including chronic inflammatory, tendon tissue re-rupture, scar formation, and post-surgical peritendinous adhesion. In this work, we develop a class of hydrogel bioadhesives with tailored nanoscale phase separation for Achilles tendon repairing. To address the existing limitations of sutures, our hydrogel bioadhesives encompass three core functionalities: (i) instant and tough adhesion to Achilles tendon tissues, (ii) extraordinary long-term adhesion robustness under wet and dynamic in vivo conditions, and (iii) anti-postsurgical peritendinous adhesion. Combining our hydrogel bioadhesives with sutures, such kind of integrated approach enables a conformable yet robust biointerface with the tendon tissues, and prevents the fibroblast migration and formation of connective tissues, thus facilitating the tendon repairing. The hydrogel bioadhesives reported here open up new opportunities for the repairing of fractured Achilles tendons in diverse and complicated clinical scenarios. [ABSTRACT FROM AUTHOR]

Abstract 3D bioprinting techniques have enabled the fabrication of irregular large‐sized tissue engineering scaffolds. However, complicated customized designs increase the medical burden. Meanwhile, the integrated printing process hinders the cellular uniform distribution and local angiogenesis. A novel approach is introduced to the construction of sizable tissue engineering grafts by employing hydrogel 3D printing for modular bioadhesion assembly, and a poly (ethylene glycol) diacrylate (PEGDA)‐gelatin‐dopamine (PGD) hydrogel, photosensitive and adhesive, enabling fine microcage module fabrication via DLP 3D printing is developed. The PGD hydrogel printed micocages are flexible, allowing various shapes and cell/tissue fillings for repairing diverse irregular tissue defects. In vivo experiments demonstrate robust vascularization and superior graft survival in nude mice. This assembly strategy based on scalable 3D printed hydrogel microcage module could simplify the construction of tissue with large volume and complex components, offering promise for diverse large tissue defect repairs.

Xerosis is one of the common dermatological problems. Preparations recommended for daily care of dry skin are emollients. Emollient preparations demonstrate a moisturizing effect, they soften and smoothen the skin, keep water in the epidermis, supplement lipids of skin upper layers, and protect from external harmful agents. The purpose of this study was to develop and characterize emollients containing natural emulsifier Olivem 1000 as topical delivery systems for urea or sodium hyaluronate. The physicochemical and mechanical properties of the designed formulations were evaluated. Moreover, an ex vivo adhesion study on hairless murine skin as a model of adhesive layer was conducted and an in vivo preliminary assessment of transepidermal water loss (TEWL) was performed. The prepared emollient formulations were characterized by a smooth consistency, were easily spreadable on the skin surface, and showed no phase separation. Formulations containing xanthan gum as a thickening agent were characterized by higher viscosity, hardness, cohesiveness and adhesiveness values. The prepared emollients showed thixotropic properties and were classified as non-Newtonian shear thinning systems. All prepared emollients demonstrated bioadhesive properties. The TEWL analysis showed that the greatest decrease in the TEWL value was noted in the case of an emollient containing sodium hyaluronate, which was applied to a person with skin described as in very poor condition. The results of the conducted research indicate that the developed emollients containing natural emulsifier Olivem 1000 seem to be a promising form of care preparations for topical use in the case of chronic skin dryness. [ABSTRACT FROM AUTHOR]

We report a biocompatible hydrogel dressing based on sodium alginate-grafted poly(N-vinylcaprolactam) prepared by encapsulation of Rifampicin as an antimicrobial drug and stabilizing the matrix through the repeated freeze–thawing method. The hydrogel structure and polymer-drug compatibility were confirmed by FTIR, and a series of hydrogen-bond-based interactions between alginate and Rifampicin were identified. A concentration of 0.69% Rifampicin was found in the polymeric matrix using HPLC analysis and spectrophotometric UV–Vis methods. The hydrogel’s morphology was evaluated by scanning electron microscopy, and various sizes and shapes of pores, ranging from almost spherical geometries to irregular ones, with a smooth surface of the pore walls and high interconnectivity in the presence of the drug, were identified. The hydrogels are bioadhesive, and the adhesion strength increased after Rifampicin was encapsulated into the polymeric matrix, which suggests that these compositions are suitable for wound dressings. Antimicrobial activity against S. aureus and MRSA, with an increased effect in the presence of the drug, was also found in the newly prepared hydrogels. In vitro biological evaluation demonstrated the cytocompatibility of the hydrogels and their ability to stimulate cell multiplication and mutual cell communication. The in vitro scratch assay demonstrated the drug-loaded alginate-grafted poly(N-vinylcaprolactam) hydrogel’s ability to stimulate cell migration and wound closure. All of these results suggest that the prepared hydrogels can be used as antimicrobial materials for wound healing and care applications.

Summary: Biofilm‐forming benthic diatoms are key primary producers in coastal habitats, where they frequently dominate sunlit intertidal substrata. The development of gliding motility in raphid diatoms was a key molecular adaptation that contributed to their evolutionary success. However, the structure–function correlation between diatom adhesives utilized for gliding and their relationship to the extracellular matrix that constitutes the diatom biofilm is unknown.Here, we have used proteomics, immunolocalization, comparative genomics, phylogenetics and structural homology analysis to investigate the evolutionary history and function of diatom adhesive proteins.Our study identified eight proteins from the adhesive trails of Craspedostauros australis, of which four form a new protein family called Trailins that contain an enigmatic Choice‐of‐Anchor A (CAA) domain, which was acquired through horizontal gene transfer from bacteria. Notably, the CAA‐domain shares a striking structural similarity with one of the most widespread domains found in ice‐binding proteins (IPR021884).Our work offers new insights into the molecular basis for diatom biofilm formation, shedding light on the function and evolution of diatom adhesive proteins. This discovery suggests that there is a transition in the composition of biomolecules required for initial surface colonization and those utilized for 3D biofilm matrix formation. [ABSTRACT FROM AUTHOR]

Hydrogels are homogeneous three-dimensional polymeric networks capable of holding large amounts of water and are widely used in topical formulations. Herein, the physicomechanical, rheological, bioadhesive, and drug-release properties of hydrogels containing hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) were examined, and the intermolecular interactions between the polymers were explored. A three-level factorial design was used to form HPMC–PVP binary hydrogels. The physicomechanical properties of the binary hydrogels alongside the homopolymeric HPMC hydrogels were characterized using a texture analyzer. Rheological properties of the gels were studied using a cone and plate rheometer. The bioadhesiveness of selected binary hydrogels was tested on porcine skin. Hydrophilic benzophenone-4 was loaded into both homopolymeric and binary gels, and drug-release profiles were investigated over 24 h at 33 °C. Fourier transform infrared spectroscopy (FTIR) was used to understand the inter-molecular drug–gel interactions. Factorial design analysis supported the dominant role of the HPMC in determining the gel properties, rather than the PVP, with the effect of both polymer concentrations being non-linear. The addition of PVP to the HPMC gels improved adhesiveness without significantly affecting other properties such as hardness, shear-thinning feature, and viscosity, thereby improving bioadhesiveness for sustained skin retention without negatively impacting cosmetic acceptability or ease of use. The release of benzophenone-4 in the HPMC hydrogels followed zero-order kinetics, with benzophenone-4 release being significantly retarded by the presence of PVP, likely due to intermolecular interactions between the drug and the PVP polymer, as confirmed by the FTIR. The HPMC–PVP binary hydrogels demonstrate strong bioadhesiveness resulting from the addition of PVP with desirable shear-thinning properties that allow the formulation to have extended skin-retention times. The developed HPMC–PVP binary hydrogel is a promising sustained-release platform for topical drug delivery. [ABSTRACT FROM AUTHOR]

Hazelnut shells, the main waste deriving from hazelnut processing, represent an interesting source of active molecules useful in pharmaceutics, although they have not yet been examined in depth. A hydrosoluble extract (hazelnut shell extract, HSE) was prepared by the maceration method using a hydroalcoholic solution and used as the active ingredient of patches (prepared by casting method) consisting of composites of highly deacetylated chitosan and green clay. In vitro studies showed that the formulation containing HSE is able to stimulate keratinocyte growth, which is useful for healing purposes, and to inhibit the growth of S. aureus (Log CFU/mL 0.95 vs. 8.85 of the control after 48 h); this bacterium is often responsible for wound infections and is difficult to treat by conventional antibiotics due to its antibiotic resistance. The produced patches showed suitable tensile properties that are necessary to withstand mechanical stress during both the removal from the packaging and application. The obtained results suggest that the developed patch could be a suitable product to treat wounds. [ABSTRACT FROM AUTHOR]

Drug administration by oral delivery is the preferred route, regardless of some remaining challenges, such as short resident time and toxicity issues. One strategy to overcome these barriers is utilizing mucoadhesive vectors that can increase intestinal resident time and systemic uptake. In this study, biomimetic nanoparticles (NPs) were produced from 14 types of edible algae and evaluated for usage as oral DDSs by measuring their size, surface charge, morphology, encapsulation efficiency, mucoadhesion force, and cellular uptake into Caco-2 cells. The NPs composed of algal materials (aNPs) exhibited a spherical morphology with a size range of 126–606 nm and a surface charge of −9 to −38 mV. The mucoadhesive forces tested ex vivo against mice, pigs, and sheep intestines revealed significant variation between algae and animal models. Notably, Arthospira platensis (i.e., Spirulina) NPs (126 ± 2 nm, −38 ± 3 mV) consistently exhibited the highest mucoadhesive forces (up to 3127 ± 272 µN/mm²). Moreover, a correlation was found between high mucoadhesive force and high cellular uptake into Caco-2 cells, further supporting the potential of aNPs by indicating their ability to facilitate drug absorption into the human intestinal epithelium. The results presented herein serve as a proof of concept for the possibility of aNPs as oral drug delivery vehicles.

Known as the degenerative disease of the knee with the highest prevalence, knee osteoarthritis (KOA) is characterized by a gradual destructive mechanism that, in severe cases, can provoke the need for total knee substitution. As the disease progresses, various enzymatic, immunological, and inflammatory processes abnormally degrade hyaluronic acid (HA), SF’s main component, and affect the concentrations of specific proteins, with the final results seriously endangering synovial fluid (SF)’s rheological and tribological features and characteristics. No effective treatments have been found to stop the progression of KOA, but the injection of HA-based viscoelastic gels has been considered (alone or combined with physiotherapy (PT)) as an alternative to symptomatic therapies. In order to evaluate the effect of viscosupplementation and PT on the characteristics of SF, SF aspirated from groups treated for KOA (HA Kombihylan® and groups that received Kombihylan® and complex PT) was analyzed and compared from analytical, spectrophotometrical, and rheological perspectives. In the patients treated with PT, the SF extracted 6 weeks after viscosupplementation had a superior elastic modulus (G′) and viscous moduli (G″), as well as a homogeneous distribution of proteins and polysaccharides. The viscosupplementation fluid improved the bioadhesive properties of the SF, and the use of the viscosupplementation fluid in conjunction with PT was found to be favorable for the distribution of macromolecules and phospholipids, contributing to the lubrication process and the treatment of OA-affected joints.

The aim of this study was to develop a suitable clotrimazole (CLT)-loaded mucoadhesive vaginal gel (CLT-MVG) for topical applications in vaginal candidiasis. Ten CLT-MVG formulations were prepared, consisting of mixtures of acid polyacrylic (Carbopol 940) and polyethene oxides, Sentry Polyox WSRN 1105 or 750, according to an experimental D-optimal design, and CLT was suspended at a ratio of 1%. The prepared CLT-MVG formulations were studied in vitro, and the formulation containing Carbopol 940 0.89% combined with PEO 1105 1.39% was identified with the optimal rheological and in vitro bioadhesion properties, ensuring the prolonged release of CLT, with a similarity factor greater than 50, indicating dissolution profile similarity for three batches of the optimized formulation. This optimized formulation showed a pH in the tolerance range, and an adequate ex vivo mucoadhesion time, while the FT-IR studies revealed no interactions between the excipients and CLT. The microscopic analysis identified a mean particle size of suspended CLT of 5.24 ± 0.57 μm. The in vitro antifungal activity of the optimized formulation was tested on twenty strains of Candida albicans and proved to be better compared to a marketed clotrimazole preparation, showing a greater inhibition effect (p < 0.05). The optimized formulation could be a good candidate for the local treatment of vaginal mycosis. [ABSTRACT FROM AUTHOR]

Phytoplankton and diatom microalgae species cause biofouling by adhering to the surfaces, especially in closed cultivation systems such as tubular photobioreactors. This biofilm formation blocks the sunlight; after harvesting, it is necessary to clean the reactor. This cleaning process causes loss not only for time and finance but also in terms of environmental pollution due to using toxic chemicals and excess water usage. This study aimed to investigate the reduction of the microorganism cell adhesion on the hybrid surface. To succeed in this, the composite surface of tetraethoxysilane (TEOS) and lactic acid (LA) was prepared by the sol-gel process. Then the hybrid surfaces were coated on glass slides by the dip coating method. The wettability performance of the TEOS-LA hybrid surface was investigated using contact angle measurement and light transmittance. The wettability result showed that the superhydrophilic surface having 54 mJ/m2 of surface free energy values was obtained. An increase in the lactic acid content of the composite films increased the surface free energy (SFE) values decreasing the water contact angle. A pencil hardness test characterized the mechanical strength of the surfaces, and it was determined that the hardness of the composite films was decreased by increasing the LA content of the composite films. Resultantly, it is found that the TEOS-LA superhydrophilic composite film reduces the adhesion of microalgae.

Dry and hot/wet lap shear specimens were prepared and tested to evaluate catechol-containing additives in a model epoxy adhesive. We specifically compared adding neutral dopamine, which is capable of being covalently incorporated into the epoxy network, with molecular analogues that contain methyl, methoxy and fluorine rather than hydroxyl groups. We found that catechol was unique among these additives in improving both dry and hot/wet lap shear strength. While neutral dopamine can only be added to relatively low concentrations due to solubility limitations, other catechol-containing polymers and monomers based on maleimide also showed increases in dry and hot/wet lap shear strength upon incorporation. Dynamic mechanical analysis measurements suggested that the differences observed were not likely due to differences in either polymer mechanical properties or polymer topology. [ABSTRACT FROM AUTHOR]

Purpose: Viburnum opulus L. fruits have been used in traditional medicine in the Turkish population for kidney problems, hypoglycemic and cough relaxant activities. This study aimed to prepare V. opulus extract-loaded orally disintegrating films (ODFs) to enhance oral absorption and improve patient compliance. Methods: ODF formulations were prepared using the solvent casting method. Carboxymethyl cellulose (0.5%, 1%, 1.5% w/w) and chitosan (0.5%, 1%, 1.5% w/w) were selected as film-forming polymers and glycerol was utilized as a plasticizer. Chlorogenic acid is the major metabolite of V. opulus fruits. The chlorogenic acid content in formulations and the plant extract was measured using high-performance thin-layer chromatography (HPTLC). Characterization studies on the formulations such as elongation at break, tensile strength, Young's modulus, DSC, SEM, and FT-IR were conducted. Bioadhesion, in vitro disintegration, and in vitro release studies were performed. Results: Desired mechanical and morphological properties were obtained for ODFs. Disintegration times (15.38 ± 0.88 s) and release studies (85.19% at 30 min) showed that the 0.5% chitosan films were the most convenient formulation for delivering V. opulus extract. Conclusion: ODFs were evaluated as a smart delivery route for phytochemicals avoiding any gastrointestinal effects and enhancing oral absorption. [ABSTRACT FROM AUTHOR]

Purpose: Captopril is one of the most important angiotensin converting enzyme inhibitors and still the gold standard for the treatment of hypertension and congestive heart failure. However, it has a short duration of action and about 1–2 h biological half-life. Formulation of a sustained release dosage form of captopril is difficult due to its instability at the alkaline pH of the gastrointestinal tract. Therefore, incorporation of captopril within bioadhesive cubic nanoparticles or cubosomes could be an alternative way to improve its efficiency. Methods: Monoolein dispersions containing captopril were prepared by the homogenization technique using different concentrations of monoolein and poloxamer. Characterization of these dispersions was performed by measuring particle size, small angle X-ray diffraction, cryo transmission electron microscopy, entrapment efficiency, and in-vitro release of captopril. Results: Monoolein cubic nanoparticles with mean particle sizes between 250 and 350 nm were obtained after autoclaving the homogenized dispersions. The cubic structure was confirmed by the presence of the three characteristic X-ray diffraction peaks of P-type cubic phase and from cryo transmission pictures. A slow release of captopril from cubosomes was observed within 8 h with a high bioadhesion capacity where about 75% of these cubosomes adhered to stomach tissues. Conclusion: Monoolein cubosomes could be used successfully as carriers for captopril where they slowly released it and had a good adhesion property to stomach tissues. [ABSTRACT FROM AUTHOR]

Skin inflammation is a symptom of many skin diseases, such as eczema, psoriasis, and dermatitis, which cause rashes, redness, heat, or blistering. The use of natural products with anti-inflammatory properties has gained importance in treating these symptoms. Ursolic acid (UA), a promising natural compound that is used to treat skin diseases, exhibits low aqueous solubility, resulting in poor absorption and low bioavailability. Designing topical formulations focuses on providing adequate delivery via application to the skin surface. The aim of this study was to formulate and characterize lipid-surfactant-based systems for the delivery of UA. Microemulsions and liquid crystalline systems (LCs) were characterized by polarized light microscopy (PLM), rheology techniques, and textural and bioadhesive assays. PLM supported the self-assembly of these systems and elucidated their formation. Rheologic examination revealed pseudoplastic and thixotropic behavior appropriate, and assays confirmed the ability of these formulations to adhere to the skin. In vivo studies were performed, and inflammation induced by croton oil was assessed for response to microemulsions and LCs. UA anti-inflammatory activities of ~60% and 50% were demonstrated by two microemulsions and 40% and 35% by two LCs, respectively. These data support the continued development of colloidal systems to deliver UA to ameliorate skin inflammation. [ABSTRACT FROM AUTHOR]

A hydrogel with bioadhesive function has high water content, inherent flexibility, adjustable mechanical strength, adequate biocompatibility, and a wide range of application prospects in the field of biomedicine. However, achieving reversible and robust adhesion between the hydrogel and the biological interface remains a challenge, including slow adhesive formation, weak adhesion, low biocompatibility, poor mechanical matching with tissues, and the lack of a benign detachment that can be triggered. Bioadhesive hydrogels adhere to distinct biological tissues and are used in biomedicine through the interaction between interfaces. The adhesion mechanism is usually a combination of multiple interactions in which one interaction is dominant. This article summarizes the preparation of bioadhesive hydrogels, the characteristics of biological interfaces, the methods of enhancing adhesion, and measuring the adhesion of hydrogels. These will assist researchers in developing adhesion strategies and accurately measuring adhesive forces according to contrasting biological interfaces. [ABSTRACT FROM AUTHOR]

Diabetic wounds are challenging to heal due to complex pathogenic abnormalities. Routine treatment with acid fibroblast growth factor (aFGF) is widely used for diabetic wounds but hardly offers a satisfying outcome due to its instability. Despite the emergence of various nanoparticle-based protein delivery approaches, it remains challenging to engineer a versatile delivery system capable of enhancing protein stability without the need for complex preparation. Herein, a polyphenol-driven facile assembly of nanosized coacervates (AE-NPs) composed of aFGF and Epigallocatechin-3-gallate (EGCG) was constructed and applied in the healing of diabetic wounds. First, the binding patterns of EGCG and aFGF were predicted by molecular docking analysis. Then, the characterizations demonstrated that AE-NPs displayed higher stability in hostile conditions than free aFGF by enhancing the binding activity of aFGF to cell surface receptors. Meanwhile, the AE-NPs also had a powerful ability to scavenge reactive oxygen species (ROS) and promote angiogenesis, which significantly accelerated full-thickness excisional wound healing in diabetic mice. Besides, the AE-NPs suppressed the early scar formation by improving collagen remodeling and the mechanism was associated with the TGF-β/Smad signaling pathway. Conclusively, AE-NPs might be a potential and facile strategy for stabilizing protein drugs and achieving the scar-free healing of diabetic wounds. Diabetic chronic wound is among the serious complications of diabetes that eventually cause the amputation of limbs. Herein, a polyphenol-driven facile assembly of nanosized coacervates (AE-NPs) composed of aFGF and EGCG was constructed. The EGCG not only acted as a carrier but also possessed a therapeutic effect of ROS scavenging. The AE-NPs enhanced the binding activity of aFGF to cell surface receptors on the cell surface, which improved the stability of aFGF in hostile conditions. Moreover, AE-NPs significantly accelerated wound healing and improved collagen remodeling by regulating the TGF-β/Smad signaling pathway. Our results bring new insights into the field of polyphenol-containing nanoparticles, showing their potential as drug delivery systems of macromolecules to treat diabetic wounds. [Display omitted] [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to investigate the direct and indirect influence of fluoridated toothpastes and fluoride‐free toothpaste with hydroxyapatite (HAP) as active ingredient on initial bacterial colonization on enamel in situ. Methods: For this clinical‐experimental pilot study, eight subjects were instructed to brush their teeth with three different toothpastes (Elmex®: 1400 ppm AmF, Meridol®: 1400 ppm AmF +SnF2, Karex®: HAP), using each for two consecutive days. As a control, brushing without toothpaste was performed. To evaluate bacterial colonization, subject wore splints with buccally placed bovine enamel platelets overnight. Two modes were tested. In a first pass (regimen A), the splints were inserted after toothbrushing to examine the indirect effects of the dentifrices. In order to investigate the direct effects, the specimens were brushed in situ in a second pass (regimen B). Biofilm formation was visualized and quantified using fluorescence microscopy (DAPI and BacLight) and transmission electron microscopy (TEM). Results: For brushing regimen A (indirect effect of dentifrices), no statistical differences were detected between any of the tested dentifrices or the control. Likewise, no statistically significant differences were recorded for brushing regimen B (direct effect of dentifrices). Furthermore, no differences between the different brushing techniques were determined with regard to the ultrastructure of the overnight biofilm. Conclusion: Within the limitations of the present pilot study, it can be concluded that in patients with good oral hygiene, dentifrices and their chemical composition have no statistically significant effect on the initial bacterial colonization of enamel platelets in situ, irrespectively of the mode of application. [ABSTRACT FROM AUTHOR]

Bacterial colonization occurs on all biological and artificial surfaces in the oral cavity. The formation of multicellular biofilms or settlement of misallocated species can cause caries (diet‐depending acidification), periodontal diseases, peri‐implantitis, or denture‐associated stomatitis. Inhibition or delay of initial adhesion should strongly reduce dental interventions. However, no strategy is found to mildly manage bacterial colonization in this complex physiological environment, that is, without toxic, antibacterial, or antiseptic approaches. It is shown in a previous study that micro‐ and submicrometer surface topographies, which can effectively control initial bacterial adhesion in other application areas, do not have any significant impact within the oral cavity. Herein, a simple approach is presented to reduce initial microbial surface colonization by plain biphasic textures with defined combinations of hydrophobic and hydrophilic phases (SiO2, NH2, CH2, CH3, F3). A significant reduction of microbial adhesion on textures in the nano‐ and microscale (150 nm and 2.4 μm) compared to respective monophasic substrates is observed. This might be a new design principle for dental materials, to inhibit microbial colonization in critical scenarios, at least for shorter time scales (

The extracellular matrix (ECM), an integral component of all organs, is inherently tissue adhesive and plays a pivotal role in tissue regeneration and remodeling. However, man-made three-dimensional (3D) biomaterials that are designed to mimic ECMs do not intrinsically adhere to moisture-rich environments and often lack an open macroporous architecture required for facilitating cellularization and integration with the host tissue post-implantation. Furthermore, most of these constructs usually entail invasive surgeries and potentially a risk of infection. To address these challenges, we recently engineered biomimetic and macroporous cryogel scaffolds that are syringe injectable while exhibiting unique physical properties, including strong bioadhesive properties to tissues and organs. These biomimetic catechol-containing cryogels were prepared from naturally-derived polymers such as gelatin and hyaluronic acid and were functionalized with mussel-inspired dopamine (DOPA) to impart bioadhesive properties. We found that using glutathione as an antioxidant and incorporating DOPA into cryogels via a PEG spacer arm led to the highest tissue adhesion and improved physical properties overall, whereas DOPA-free cryogels were weakly tissue adhesive. As shown by qualitative and quantitative adhesion tests, DOPA-containing cryogels were able to adhere strongly to several animal tissues and organs such as the heart, small intestine, lung, kidney, and skin. Furthermore, these unoxidized (i.e., browning-free) and bioadhesive cryogels showed negligible cytotoxicity toward murine fibroblasts and prevented the ex vivo activation of primary bone marrow-derived dendritic cells. Finally, in vivo data suggested good tissue integration and a minimal host inflammatory response when subcutaneously injected in rats. Collectively, these minimally invasive, browning-free, and strongly bioadhesive mussel-inspired cryogels show great promise for various biomedical applications, potentially in wound healing, tissue engineering, and regenerative medicine.

Biomimetic adhesives with a stiff fibre-reinforced base layer generate strong attachment, even without bioinspired micropatterning of the contact surface. However, current fibre-reinforced adhesive designs are still less versatile with respect to substrate variability than their biological counterparts. In this study, we enhance the comformability of a fibre-reinforced adhesive on curved substrates by adding bioinspired soft backings. We designed and fabricated soft backing variations (polyurethane foams and silicone hydroskeletons) with varying compressive stiffnesses that mimic the soft viscoelastic structures in the adhesive appendages of tree frogs, geckos and other animals. The backings were mounted on a smooth silicone layer enforced with a polyester mesh, and we experimentally investigated the contact area and friction performance of these adhesives on a curved substrate. The results show that the contact area and friction created by a fibre-reinforced adhesive with a soft backing in contact with a non-flat substrate scale inversely with backing stiffness. The integration of stiff fibre-reinforcement with a compressible backing represents an important step in bringing bioinspired adhesives out of the laboratory and into the real world, for example in soft robotic grippers. Moreover, our findings stimulate further research into the role of soft tissues in biological adhesive systems.

The study aims to investigate the adhesion of a hydrogel made of cross-linked low-methyl esterified pectin to rat intestinal serosa ex vivo. The adhesivity of the FeP hydrogel, which was cross-linked by Fe3+ cations, exceeded that of hydrogels cross-linked by Ca2+, Zn2+, and Al3+ cations. The concentration of the cross-linking cation failed to influence the adhesion of the pectin hydrogel to the serosa. The mechanical properties and surface microrelief of the pectin hydrogel were influenced by the type and concentration of the cross-linking cations. Fe3+ cations form a harder and more elastic gel than Ca2+ cations. Scanning electron microscopy analysis revealed the characteristic surface pattern of FeP hydrogel and its denser internal structure compared to Ca2+ cross-linked hydrogel. The effect of the salt composition of the adhesion medium was shown since the FeP hydrogel's adhesion to the serosa was lower in physiological solutions than in water, and adhesion in Hanks' solution was higher than in phosphate buffered saline. Serum proteins and peritoneal leukocytes did not interfere with the serosal adhesion of the FeP hydrogel. Pre-incubation in Hanks' solution for 24 h significantly reduced the adhesion of the FeP hydrogel to the serosa, regardless of the pH of the incubation. Thus, serosal adhesion combined with excellent stability and mechanical properties in physiological environments appeared to be advantages of the FeP hydrogel, demonstrating it to be a promising bioadhesive for tissue engineering. [ABSTRACT FROM AUTHOR]

Due to the low solubility and poor bioavailability of Ticagrelor (TIC), the current study developed a structured bioadhesive core-shell drug delivery system to address it. Ticagreior solid dispersion (T-SD) was fabricated using the uniaxial electrostatic spray method. Ticagrelor bio adhesive solid dispersion (T-BSD) was also prepared using the coaxial electrostatic spray technique. The adhesion of T-BSD to each intestinal segment was determined using biological adhesion test. The compartment model was used to study the plasma concentration-time curve and related pharmacokinetic parameters. The results of bioadhesion tests showed a positive adhesion effect of T-BSD in each intestinal segment. The maximum plasma concentration (Cmax) of T-BSD was increased to 777.08ng/mL compared with the free drug (367ng/mL). Similarly, t1/2, MRT and Tmax of T-BSD (12.1h, 9.4h, 4h) were higher than the free drug (11.2h, 8.6h, 1h), respectively. The relative bioavailability of T-BSD was further increased to 430% compared with the free drug. The findings collectively revealed that the coaxial-electrospray technique could be a promising way to improve the bioavailability of TIC. [ABSTRACT FROM AUTHOR]

Background: Poly(acrylic acid) (PAA) is a water-soluble synthetic polymer with tissue-adhesive properties. When PAA is mixed with polyvinylpyrrolidone (PVP) in water, it forms a water-insoluble precipitate that neither swells nor adheres to tissues. Methods and Results: We developed a novel solid/solution interface complexation method to obtain a water-swellable PAA/PVP complex. First, PAA solution was dried up in a vessel to form a film. The PAA film was then immersed in an aqueous PVP solution to obtain a highly swollen PAA/PVP hydrogel. Heat drying of the hydrogel yielded a transparent film, while freeze-drying the hydrogel provided a soft sponge. Both the PAA/PVP film and sponge could be re-swelled by water to obtain a bioadhesive gel. A relatively larger specific surface area of the sponge than that of the film led to a more rapid swelling and water absorption behavior and quick adhesion to tissues. The addition of hyaluronic acid (HA) improved the mechanical characteristics of the sponges. PAA/PVP/HA sponges had low cytotoxicity, and they exhibited high hemostatic efficiency in clinical studies after dialysis treatment or tooth extraction, even in patients on antithrombotic drugs. Conclusions: Such bioadhesive materials consisting of low-toxicity polymers have a high potential for use in medical hemostatic devices. [ABSTRACT FROM AUTHOR]

Unworn masks and masks provided to us after having been worn conformable to law (mandatory wearing of masks) served as test objects. In order to identify the distribution of living microorganisms on the surface of a mask dependent on exposure time and distance from the human face we conducted a staining study using the bengal rose method. The regular deposition of living microorganisms on artificial mask surfaces was more intense in the areas close to the mouth and nose. A time dependent accumulation was larger on the inside in comparison to the outside of the mask, even if the mask was not worn but only left in the room. The most interesting finding was the ability of microorganisms to penetrate all layers of the mask. We therefore conclude that masks are a suitable substrate for the cultivation of germs, even when not worn. Colonisation increases with human use and with time.

Secretome is involved in almost all physiological, developmental, and pathological processes, but to date there is still a lack of highly-efficient research strategy to comprehensively study the secretome of invertebrates. Adhesive secretion is a ubiquitous and essential physiological process in aquatic invertebrates with complicated protein components and unresolved adhesion mechanisms, making it a good subject for secretome profiling studies. Here we proposed a computational pipeline for systematic profiling of byssal secretome based on spatiotemporal transcriptomes of scallop. A total of 186 byssus-related proteins (BRPs) were identified, which represented the first characterized secretome of scallop byssal adhesion. Scallop byssal secretome covered almost all of the known structural elements and functional domains of aquatic adhesives, which suggested this secretome-profiling strategy had both high efficiency and accuracy. We revealed the main components of scallop byssus (including EGF-like domain containing proteins, the Tyr-rich proteins and 4C-repeats containing proteins) and the related modification enzymes primarily contributing to the rapid byssus assembly and adhesion. Spatiotemporal expression and co-expression network analyses of BRPs suggested a simultaneous secretion pattern of scallop byssal proteins across the entire region of foot and revealed their diverse functions on byssus secretion. In contrast to the previously proposed “root-initiated secretion and extension-based assembly” model, our findings supported a novel “foot-wide simultaneous secretion and in situ assembly” model of scallop byssus secretion and adhesion. Systematic analysis of scallop byssal secretome provides important clues for understanding the aquatic adhesive secretion process, as well as a common framework for studying the secretome of non-model invertebrates.

Eutectogels (Egels) are an emerging class of soft ionic materials outperforming traditional temperature-intolerant hydrogels and costly ionogels. Due to their excellent elasticity, non-volatile nature, and adhesion properties, Egels are attracting a great deal of interest in the biomedical space. Herein, we report the first example of adhesive Egels loading drug nanocrystals (Egel-NCs) for controlled delivery to mucosal tissues. These soft materials were prepared using gelatin, glycerine, a deep eutectic solvent (DES) based on choline hydrochloride and glycerol, and nanocrystallised curcumin, a model drug with potent antimicrobial and anti-inflammatory activities. We first explored the impact of the biopolymer concentration on the viscoelastic and mechanical properties of the networks. Thanks to the dynamic interactions between gelatin and the DES, the Egel showed excellent stretchability and elasticity (up to ≈160%), reversible gel-sol phase transition at mild temperature (≈50 ​°C), 3D-printing ability, and good adhesion to mucin protein (stickiness ≈40 ​kPa). In vitro release profiles demonstrated the ability of the NCs-based Egel to deliver curcumin for up to four weeks and deposit significantly higher drug amounts in excised porcine mucosa compared to the control cohort. All in all, this study opens new prospects in designing soft adhesive materials for long-acting drug delivery and paves the way to explore novel eutectic systems with multiple therapeutic applications.

Although some methods for measuring bioadhesion/mucoadhesion have been proposed, a standardized method is not yet available. This is expected to hinder systematic comparisons of results across studies. This study aimed to design a single/systematic in vitro method for measuring bioadhesion/mucoadhesion that is applicable to various pharmaceutical dosage forms. To this end, we measured the peak force and work of adhesion of minitablets, pellets, and a bioadhesive emulsion using a texture analyzer. Porcine tissue was used to simulate human stomach/skin conditions. The results of these formulations were then compared to those for formulations without the bioadhesive product. We conducted a case study to assess the stability of a bioadhesive emulsion. The results for the two parameters assessed were contact time = 60 s and contact force = 0.5 N at a detachment speed of 0.1 mm/s. Significant differences were observed between the bioadhesive and control formulations, thus demonstrating the adhesive capacity of the bioadhesive formulations. In this way, a systematic method for assessing the bioadhesive capacity of pharmaceutical dosage forms was developed. The method proposed here may enable comparisons of results across studies, i.e., results obtained using the same and different pharmaceutical formulations (in terms of their bioadhesion/mucoadhesion capacity). This method may also facilitate the selection of potentially suitable formulations and adhesive products (in terms of bioadhesive properties). [ABSTRACT FROM AUTHOR]

This study was aimed to prepare, optimize and characterize cost-effective and mucoadhesive dental minocycline microspheres for the treatment of periodontitis. There is a need and scope for a costeffective novel formulation of minocycline for periodontitis that can be delivered to the base of the pockets and is biodegradable, bioadhesive, and non-toxic. The Central composite design (CCD) was utilized to study the effects of process variables (5 levels) on the responses including size (R1), drug-entrapment (R2), mucoadhesion (R3), and percent in-vitro drug release (R4). Chitosan-minocycline microspheres were prepared by W/O emulsion technique using glutaraldehyde and sodium tripolyphosphate as different cross-linking agents. Results indicated that the concentration of polymer, drug, cross-linking agent, and cross-linking method significantly affected drug incorporation efficiencies and microsphere characteristics. The minocycline release from the microspheres provided a retarded release up to 8 h and all concentrations were observed to be more than the minimum inhibitory concentration (MIC) required for inhibiting the growth of Staphylococcus aureus. The study concluded that the microspherical system provides advantages over systemic drug administration, including reduction of systemic side effects and dramatic increase in sustained drug concentrations in the gingival cervicular fluid. Local delivery by means of microspheres has several advantages over systemic drug intake including lesser systemic side effects, reduction of dose, mucoadhesiveness, and cost-effectiveness. [ABSTRACT FROM AUTHOR]

Simple Summary: Before entering metamorphosis, the larvae of Drosophila flies expel a transparent glue from their mouth, which solidifies in contact with air within seconds and fixes the animal to a substrate (wood, leaves, fruits, stones, etc.) for several days until the adult emerges. This glue displays interesting adhesive properties, as it can adhere to various substrates with strengths similar to strongly adhesive commercial tapes. We review here the production, aspect, composition and role of this glue in the model organism Drosophila melanogaster and in other Drosophila species. The glue is made of several proteins, which have diversified rapidly during evolution. With the large diversity of substrates and environmental conditions where fly species undergo metamorphosis, Drosophila glue provides a large source of inspiration for the development of biomimetic adhesive materials. We propose several potential avenues of research for the future development of Drosophila-inspired adhesive materials. The glue produced by Drosophila larvae to attach themselves to a substrate for several days and resist predation until the end of metamorphosis represents an attractive model to develop new adhesives for dry environments. The adhesive properties of this interesting material have been investigated recently, and it was found that it binds as well as strongly adhesive commercial tapes to various types of substrates. This glue hardens rapidly after excretion and is made of several proteins. In D. melanogaster, eight glue proteins have been identified: four are long glycosylated mucoproteins containing repeats rich in prolines, serines and threonines, and four others are shorter proteins rich in cysteines. This protein mix is produced by the salivary glands through a complex packaging process that is starting to be elucidated. Drosophila species have adapted to stick to various substrates in diverse environmental conditions and glue genes appear to evolve rapidly in terms of gene number, number of repeats and sequence of the repeat motifs. Interestingly, besides its adhesive properties, the glue may also have antimicrobial activities. We discuss future perspectives and avenues of research for the development of new bioadhesives mimicking Drosophila fly glue. [ABSTRACT FROM AUTHOR]

Poly(acrylic acid) (PAA) is a water-soluble synthetic polymer that exhibits bioadhesive properties and has been applied in various novel medical devices, such as drug-delivery carriers and hemostatic agents. PAA forms a water-insoluble complex when mixed with polyvinylpyrrolidone (PVP). If PAA and PVP are mixed in water, they form an aggregated precipitate, which neither swells nor adheres to tissues. The formation of the hydrophobic complex was caused by hydrophobic interactions between the main chains of both polymers aligned the same as a zipper. To hinder the zipper-like alignment of the polymer main chains, hyaluronic acid (HA), a macromolecular viscous polysaccharide, was added to the PVP solution prior to complex formation. When the initial concentration of PAA was lower than 0.05%, HA effectively prevented the aggregation of PAA/PVP complexes and resulted in a slightly clouded suspension. Freeze-drying of the mixture yielded a soft white sponge, which could immediately swell in water to form a highly bioadhesive hydrogel. The PAA/PVP complex prepared with HA exhibited high hemostatic efficiency in clinical studies, even in patients on antithrombotic drugs. [ABSTRACT FROM AUTHOR]