Preparation and properties of polyvinyl alcohol/N-succinyl chitosan/lincomycin composite antibacterial hydrogels for wound dressing

Multi-dynamic-bond cross-linked antibacterial and adhesive hydrogel based on boronated chitosan derivative and loaded with peptides from Periplaneta americana with on-demand removability

The design and development of a bio-adhesive hydrogel with on-demand removability and excellent antibacterial activities are meaningful to achieve high wound closure effectiveness and post-wound-closure care, which is desirable in clinical applications. In this work, a series of adhesive antioxidant antibacterial hydrogels containing peptides from Periplaneta americana (PAP) were prepared through multi-dynamic-bond cross-linking among 3,4-dihydroxybenzaldehyde (DBA) containing catechol and aldehyde groups and chitosan grafted with 3-carboxy-4-fluorophenylboronic acid (CS-FPBA) to enable the effective adhesion of skin tissues and prevention of bacterial infection of wound. PAP was derived from alcohol-extracted residues generated during the pharmaceutical process, aiming to minimize resource wastage and achieve the high-value development of such a medicinal insect. The hydrogel was prepared by freezing-thawing with no toxic crosslinkers. The multi-dynamic-bond cross-linking of dynamic borate ester bonds and dynamic Schiff base bonds can achieve reversible breakage and re-formation and the adhesive strength of CS-FPBA-DBA-P-gel treated with a 20 % glucose solution dramatically decreased from 3.79 kPa to 0.35 kPa within 10 s. Additionally, the newly developed hydrogel presents ideal biocompatibility, hemostasis and antibacterial activity against Staphylococcus aureus and Escherichia coli compared to commercial chitosan gel (approximately 50 % higher inhibition rate), demonstrating its great potential in dealing with infected full-thickness skin wounds.

A novel biological antibacterial polyvinyl alcohol/polyionic liquid hydrogel for wound dressing

The release of antibiotics or anions by traditional bacteriostatic agents led to the development of bacterial drug resistance and environmental pollution. Ionic liquids (ILs) have become important choices for antibacterial agents because of their excellent physical, chemical and biological properties. In this paper, the bioactivities of 1-vinyl-3-butylimidazolium chloride ([VBIM]Cl, IL) and poly (1-vinyl-3-butylimidazolium chloride) (P[VBIM]Cl, PIL) were evaluated, and the potential antibacterial material was used to synthesize hydrogels. Using the colony formation assay and the Oxford cup method, antibacterial effect of IL and PIL were tested. Cell-Counting-Kit-8 (CCK-8) experiments were used to study the IC50 (half maximal inhibitory concentration) values of IL and showed 1.47 mg/mL, 0.35 mg/mL and 0.33 mg/mL at 24 h, 48 h and 72 h, respectively. The IC50 value of PIL were 12.15 μg/mL, 12.06 μg/mL and 11.76 μg/mL at 24 h, 48 h and 72 h, respectively. The PIL is further crosslinked with polyvinyl alcohol (PVA) to form a novel hydrogel through freeze-thaw cycles. The newly fabricated hydrogel exhibited a high water content, excellent water absorption properties and outstanding mechanical performance. Using the colony formation assay and the inhibition zone assay, the hydrogels exhibited favorable antibacterial effects (against E.coli and S.aureus) such that nearly 100% of the bacteria were killed in liquid medium while cultivating with H4 (synthesized by 0.5 g PIL and 1g PVA). In addition, the cytotoxicity of PIL was significantly reduced through hydrogen bond crosslinking. H4 showed the highest antibacterial activity and a good biocompatibility. The results indicated that the PVA&PIL hydrogels had great potential for wound dressing.

Novel 3D printed polysaccharide-based materials with prebiotic activity for potential treatment of diaper rash

Diaper rash, mainly occurring as erythema and itching in the diaper area, causes considerable distress to infants and toddlers. Increasing evidence suggests that an unequal distribution of microorganisms on the skin contributes to the development of diaper dermatitis. Probiotic bacteria, like Staphylococcus epidermidis, are crucial for maintaining a healthy balance in the skin's microbiome, among others, through their fermentative metabolites, such as short-chain fatty acids. Using a defined prebiotic as a carbon source (e.g., as part of the diaper formulation) can selectively trigger the fermentation of probiotic bacteria. A proper material choice can reduce diaper rash incidence by diminishing the skin exposure to wetness and faeces. Using 3D printing, we fabricated carbon-rich materials for the top sheet layer of baby diapers that enhance the probiotic activity of S. epidermidis. The developed materials' printability, chemical composition, swelling ability, and degradation rate were analysed. In addition, microbiological tests evaluated their potential as a source of in situ short-chain fatty acid production. Finally, biocompatibility testing with skin cells evaluated their safety for potential use as part of diapers. The results demonstrate a cost-effective approach for producing novel materials that can tailor the ecological balance of the skin microflora and help treat diaper rash.

Multifunctional antibacterial hydrogels for chronic wound management

Chronic wounds have gradually evolved into a global health challenge, comprising long-term non-healing wounds, local tissue necrosis, and even amputation in severe cases. Accordingly, chronic wounds place a considerable psychological and economic burden on patients and society. Chronic wounds have multifaceted pathogenesis involving excessive inflammation, insufficient angiogenesis, and elevated reactive oxygen species levels, with bacterial infection playing a crucial role. Hydrogels, renowned for their excellent biocompatibility, moisture retention, swelling properties, and oxygen permeability, have emerged as promising wound repair dressings. However, hydrogels with singular functions fall short of addressing the complex requirements associated with chronic wound healing. Hence, current research emphasises the development of multifunctional antibacterial hydrogels. This article reviews chronic wound characteristics and the properties and classification of antibacterial hydrogels, as well as their potential application in chronic wound management.

Recent advances in harnessing biological macromolecules for wound management: A review

Wound dressings (WDs) are an essential component of wound management and serve as an artificial barrier to isolate the injured site from the external environment, thereby helping to prevent exogenous infections and supporting healing. However, maintaining a moist wound environment, providing protection from infection, good biocompatibility, and allowing for gas exchange, remain a challenge in device design. Functional wound dressings (FWDs) prepared from hybrid biological macromolecule-based materials can enhance efficacy of these systems for skin wound management. This review aims to provide an overview of the state-of-the-art FWDs within the field of wound management, with a specific focus on hybrid biomaterials, techniques, and applications developed over the past five years. In addition, we highlight the incorporation of biological macromolecules in WDs, the emergence of smart WDs, and discuss the existing challenges and future prospects for the development of advanced WDs.

Advancements in Regenerative Hydrogels in Skin Wound Treatment: A Comprehensive Review

This state-of-the-art review explores the emerging field of regenerative hydrogels and their profound impact on the treatment of skin wounds. Regenerative hydrogels, composed mainly of water-absorbing polymers, have garnered attention in wound healing, particularly for skin wounds. Their unique properties make them well suited for tissue regeneration. Notable benefits include excellent water retention, creating a crucially moist wound environment for optimal healing, and facilitating cell migration, and proliferation. Biocompatibility is a key feature, minimizing adverse reactions and promoting the natural healing process. Acting as a supportive scaffold for cell growth, hydrogels mimic the extracellular matrix, aiding the attachment and proliferation of cells like fibroblasts and keratinocytes. Engineered for controlled drug release, hydrogels enhance wound healing by promoting angiogenesis, reducing inflammation, and preventing infection. The demonstrated acceleration of the wound healing process, particularly beneficial for chronic or impaired healing wounds, adds to their appeal. Easy application and conformity to various wound shapes make hydrogels practical, including in irregular or challenging areas. Scar minimization through tissue regeneration is crucial, especially in cosmetic and functional regions. Hydrogels contribute to pain management by creating a protective barrier, reducing friction, and fostering a soothing environment. Some hydrogels, with inherent antimicrobial properties, aid in infection prevention, which is a crucial aspect of successful wound healing. Their flexibility and ability to conform to wound contours ensure optimal tissue contact, enhancing overall treatment effectiveness. In summary, regenerative hydrogels present a promising approach for improving skin wound healing outcomes across diverse clinical scenarios. This review provides a comprehensive analysis of the benefits, mechanisms, and challenges associated with the use of regenerative hydrogels in the treatment of skin wounds. In this review, the authors likely delve into the application of rational design principles to enhance the efficacy and performance of hydrogels in promoting wound healing. Through an exploration of various methodologies and approaches, this paper is poised to highlight how these principles have been instrumental in refining the design of hydrogels, potentially revolutionizing their therapeutic potential in addressing skin wounds. By synthesizing current knowledge and highlighting potential avenues for future research, this review aims to contribute to the advancement of regenerative medicine and ultimately improve clinical outcomes for patients with skin wounds.

An Electroconductive and Antibacterial Adhesive Nanocomposite Hydrogel for High-Performance Skin Wound Healing

Multifunctional hydrogel adhesives inhibiting infections and enabling the electrical stimulation (ES) of tissue reparation are highly desirable for the healing of surgical wounds and other skin injuries. Herein, a therapeutic nanocomposite hydrogel is designed by integrating β-cyclodextrin-embedded Ag nanoparticles (CDAgNPs) in a polyvinyl alcohol (PVA) matrix enhanced with free β-cyclodextrin (CD) and an atypical macromolecule made of β-glucan grafted with hyaluronic acid (HAG). The main objective is to develop a biocompatible dressing combining the electroconductivity and antibacterial activity of CDAgNPs with the cohesiveness and porosity of PVA and the anti-inflammatory, moisturizing, and cell proliferation-promoting properties of HAG. The last component, CD, is added to strengthen the network structure of the hydrogel. PVA/CD/HAG/CDAgNP exhibited excellent adhesion strength, biocompatibility, electroconductivity, and antimicrobial activity against a wide range of bacteria. In addition, the nanocomposite hydrogel has a swelling ratio and water retention capacity suitable to serve as a wound dressing. PVA/CD/HAG/CDAgNP promoted the proliferation of fibroblast in vitro, accelerated the healing of skin wounds in an animal model, and is hemostatic. Upon ES, the PVA/CD/HAG/CDAgNP nanocomposite hydrogel became more efficient both in vitro and in vivo further speeding up the skin healing process thus demonstrating its potential as a next-generation electroconductive wound dressing.

Fabrication of maleic anhydride-acrylamide copolymer based sodium alginate hydrogel for elimination of metals ions and dyes contaminants from polluted water

The study explores the synergy of biobased polymers and hydrogels for water purification. Polymer nanomaterial's, synthesized by combining acrylamide copolymer with maleic anhydride, were integrated into sodium alginate biopolymer using an eco-friendly approach. Crosslinking agents, calcium chloride and glutaraladehyde, facilitated seamless integration, ensuring non-toxicity, high adsorption performance, and controlled capacity. This innovative combination presents a promising solution for clean and healthy water supplies, addressing the critical need for sustainable environmental practices in water purification. In addition, the polymer sodium alginate hydrogel (MAH@AA-P/SA/H) underwent characterization via the use of several analytical procedures, such as FTIR, XPS, SEM, EDX and XRD. Adsorption studies were conducted on metals and dyes in water, and pollutant removal methods were explored. We investigated several variables (such as pH, starting concentration, duration, and absorbent quantity) affect a material's capacity to be adsorbed. Moreover, the maximum adsorption towards Cu2+ is 754 mg/g while for Cr6+ metal ions are 738 mg/g, while the adsorption towards Congo Red and Methylene Blue dye are 685 mg/g and 653 mg/g correspondingly, within 240 min. Adsorption results were further analyzed using kinetic and isothermal models, which showed that MAH@AA-P/SA/H adsorption is governed by a chemisorption process. Hence, the polymer prepared from sodium alginate hydrogel (MAH@AA-P/SA/H) has remarkable properties as a versatile material for the significantly elimination of harmful contaminants from dirty water.

Construction methods and biomedical applications of PVA-based hydrogels

Polyvinyl alcohol (PVA) hydrogel is favored by researchers due to its good biocompatibility, high mechanical strength, low friction coefficient, and suitable water content. The widely distributed hydroxyl side chains on the PVA molecule allow the hydrogels to be branched with various functional groups. By improving the synthesis method and changing the hydrogel structure, PVA-based hydrogels can obtain excellent cytocompatibility, flexibility, electrical conductivity, viscoelasticity, and antimicrobial properties, representing a good candidate for articular cartilage restoration, electronic skin, wound dressing, and other fields. This review introduces various preparation methods of PVA-based hydrogels and their wide applications in the biomedical field.

Harnessing the Potential of Chitosan and Its Derivatives for Enhanced Functionalities in Food Applications

As one of the most abundant natural polysaccharides that possess good biological activity, chitosan is extracted from chitin. Its application in the food field is being increasingly valued. However, chitosan extraction is difficult, and its poor solubility limits its application. At present, the extraction methods include the acid-base method, new chemical methods, and biological methods. The extraction rates of chitin/chitosan are 4-55%, 13-14%, and 15-28%, respectively. Different chemical modifications have different effects on chitosan, making it applicable in different fields. This article reviews and compares the extraction and chemical modification methods of chitosan, emphasizing the importance of green extraction methods. Finally, the application prospects of chitosan in the food industry are discussed. This will promote the understanding of the advantages and disadvantages of different extraction methods for chitosan as well as the relationship between modification and application, providing valuable insights for the future development of chitosan.

Hydrogels dressings based on guar gum and chitosan: Inherent action against resistant bacteria and fast wound closure

Hydrogels made with depolymerized guar gum, oxidized with theoretical oxidation degrees of 20, 35 and 50 %, were obtained via Schiff's base reaction with N-succinyl chitosan. The materials obtained were subjected to characterization by FT-IR, rheology, swelling, degradation, and morphology. Additionally, their gelation time categorized all three hydrogels as injectable. The materials' swelling degrees in Phosphate-Buffered Saline (PBS) were in the range of 26-35 g of fluid/g gel and their pore size distribution was heterogeneous, with pores varying from 67 to 93 μm. All hydrogels degraded in PBS solution, but maintained around 40 % of their initial mass after 28 days, which was more than enough time for wound healing. The biomaterials were also flexible, self-repairing, adhesive and cytocompatible and presented intrinsic actions, regardless of the presence of additives or antibiotics, against gram-positive (Staphylococcus aureus, Staphylococcus epidermidis) and gram-negative bacteria (Escherichia coli). However, the most pronounced bactericidal effect was against resistant Staphylococcus aureus - MRSA. In vivo assays, performed with 50 % oxidized gum gel, demonstrated that this material exerted anti-inflammatory effects, accelerating the healing process and restoring tissues by approximately 99 % within 14 days. In conclusion, these hydrogels have unique characteristics, making them excellent candidates for wound-healing dressings.

Development and characterization of a poloxamer hydrogel composed of human mesenchymal stromal cells (hMSCs) for reepithelization of skin injuries

Wound healing is a natural physiological reaction to tissue injury. Hydrogels show attractive advantages in wound healing not only due to their biodegradability, biocompatibility and permeability but also because provide an excellent environment for cell migration and proliferation. The main objective of the present study was the design and characterization of a hydrogel loaded with human mesenchymal stromal cells (hMSCs) for use in would healing of superficial skin injures. Poloxamer 407® was used as biocompatible biomaterial to embed hMSCs. The developed hydrogel containing 20 % (w/w) of polymer resulted in the best formulation with respect to physical, mechanical, morphological and biological properties. Its high swelling capacity confirmed the hydrogel's capacity to absorb wounds' exudate. LIVE/DEAD® assay confirm that hMSCs remained viable for at least 48 h when loaded into the hydrogels. Adding increasing concentrations of hMSCs-loaded hydrogel to the epithelium did not affect keratinocytes' viability and healing capacity and all wound area was closed in less than one day. Our study opens opportunities to exploit poloxamer hydrogels as cell carriers for the treatment of skin superficial wound.

Characterization of Cellulose Fiber Derived from Hemp and Polyvinyl Alcohol-Based Composite Hydrogel as a Scaffold Material

Cellulose nanocrystals (CNCs) were successfully extracted and purified from hemp using an alkaline treatment and bleaching process and subsequently used in conjunction with polyvinyl alcohol to form a composite hydrogel. Cellulose nanocrystals (1-10% (w/v)) were integrated into polyvinyl alcohol, and sodium tetraborate (borax) was employed as a crosslinking agent. Due to the small number of cellulose nanocrystals, no significant peak change was observed in the FT-IR spectra compared to pristine polyvinyl alcohol. The porosity was created upon the removal of the water molecules, and the material was thermally stable up to 200 °C. With the presence of cellulose nanocrystals, the melting temperature was slightly shifted to a higher temperature, while the glass transition temperature remained practically unchanged. The swelling behavior was examined for 180 min in deionized water and PBS solution (pH 7.4) at 37 °C. The degree of swelling of the composite with cellulose nanocrystals was found to be higher than that of pristine PVA hydrogel. The cell viability (%) of the prepared hydrogel with different proportions of cellulose nanocrystals was higher than that of pristine PVA hydrogel. Based on the results, the prepared composite hydrogels from cellulose nanocrystals extracted from hemp and polyvinyl alcohol were revealed to be an excellent candidate for scaffold material for medical usage.

Chitosan-Based Hydrogels for Infected Wound Treatment

Wound infections slow down the healing process and lead to complications such as septicemia, osteomyelitis, and even death. Although traditional methods relying on antibiotics are effective in controlling infection, they have led to the emergence of antibiotic-resistant bacteria. Hydrogels with antimicrobial function become a viable option for reducing bacterial colonization and infection while also accelerating healing processes. Chitosan is extensively developed as antibacterial wound dressings due to its unique biochemical properties and inherent antibacterial activity. In this review, the recent research progress of chitosan-based hydrogels for infected wound treatment, including the fabrication methods, antibacterial mechanisms, antibacterial performance, wound healing efficacy, etc., is summarized. A concise assessment of current limitations and future trends is presented.

Chitosan-Based Hydrogel in the Management of Dermal Infections: A Review

The main objective of this review is to provide a comprehensive overview of the current evidence regarding the use of chitosan-based hydrogels to manage skin infections. Chitosan, a naturally occurring polysaccharide derived from chitin, possesses inherent antimicrobial properties, making it a promising candidate for treating various dermal infections. This review follows a systematic approach to analyze relevant studies that have investigated the effectiveness of chitosan-based hydrogels in the context of dermal infections. By examining the available evidence, this review aims to evaluate these hydrogels' overall efficacy, safety, and potential applications for managing dermal infections. This review's primary focus is to gather and analyze data from different recent studies about chitosan-based hydrogels combating dermal infections; this includes assessing their ability to inhibit the growth of microorganisms and reduce infection-related symptoms. Furthermore, this review also considers the safety profile of chitosan-based hydrogels, examining any potential adverse effects associated with their use. This evaluation is crucial to ensure that these hydrogels can be safely utilized in the management of dermal infections without causing harm to patients. The review aims to provide healthcare professionals and researchers with a comprehensive understanding of the current evidence regarding the use of chitosan-based hydrogels for dermal infection management. The findings from this review can contribute to informed decision-making and the development of potential treatment strategies in this field.

New Polyvinyl Alcohol/Succinoglycan-Based Hydrogels for pH-Responsive Drug Delivery

We fabricated new hydrogels using polyvinyl alcohol (PVA) and succinoglycan (SG) directly isolated and obtained from Sinorhizobium meliloti Rm 1021 via the freeze-thaw method. Both the composition of the hydrogels and the freeze-thaw cycles were optimized to maximize the swelling ratio for the preparation of the PVA/SG hydrogels. During the optimization process, the morphology and conformational change in the hydrogel were analyzed by scanning electron microscopy, rheological measurements, and compressive tests. An optimized hydrogel with a maximum swelling ratio of 17.28 g/g was obtained when the composition of PVA to SG was 50:50 (PVA/SG 50/50) and the total number of freeze-thaw cycles was five. The PVA/SG 50/50 hydrogel had the largest pore with 51.24% porosity and the highest cross-over point (28.17%) between the storage modulus (G') and the loss modulus (G″). The PVA/SG 50/50 hydrogel showed improved thermal stability owing to its interaction with thermally stable SG chains. The improvement in the thermal stability was confirmed by thermogravimetric analysis and differential scanning calorimetry. In addition, the PVA/SG 50/50 hydrogel showed differential drug release according to the corresponding pH under acidic conditions of pH 1.2 and slightly basic conditions of pH 7.4. Furthermore, the cell viability test on the HEK-293 cell line for that hydrogel demonstrated that the PVA/SG 50/50 hydrogel was non-toxic and biocompatible. Therefore, this hydrogel could be a potential scaffold capable of pH-responsive drug delivery for chronic wound dressing applications.

Lincomycin HCl-Loaded Borneol-Based In Situ Gel for Periodontitis Treatment

Solvent exchange-induced in situ forming gel (ISG) has emerged as a versatile drug delivery system, particularly for periodontal pocket applications. In this study, we developed lincomycin HCl-loaded ISGs using a 40% borneol-based matrix and N-methyl pyrrolidone (NMP) as a solvent. The physicochemical properties and antimicrobial activities of the ISGs were evaluated. The prepared ISGs exhibited low viscosity and reduced surface tension, allowing for easy injection and spreadability. Gel formation increased the contact angle on agarose gel, while higher lincomycin HCl content decreased water tolerance and facilitated phase separation. The drug-loading influenced solvent exchange and matrix formation, resulting in thinner and inhomogeneous borneol matrices with slower gel formation and lower gel hardness. The lincomycin HCl-loaded borneol-based ISGs demonstrated sustained drug release above the minimum inhibitory concentration (MIC) for 8 days, following Fickian diffusion and fitting well with Higuchi's equation. These formulations exhibited dose-dependent inhibition of Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 8739, and Prophyromonas gingivalis ATCC 33277, and the release of NMP effectively inhibited Candida albicans ATCC 10231. Overall, the 7.5% lincomycin HCl-loaded 40% borneol-based ISGs hold promise as localized drug delivery systems for periodontitis treatment.

Hydrogel with ROS scavenging effect encapsulates BR@Zn-BTB nanoparticles for accelerating diabetic mice wound healing via multimodal therapy

The strategies for eliminating excess reactive oxygen species (ROS) or suppressing inflammatory responses on the wound bed have proven effective for diabetic wound healing. In this work, a zinc-based nanoscale metal-organic framework (NMOF) functions as a carrier to deliver natural product berberine (BR) to form BR@Zn-BTB nanoparticles, which was, in turn, further encapsulated by hydrogel with ROS scavenging ability to yield a composite system of BR@Zn-BTB/Gel (denoted as BZ-Gel). The results show that BZ-Gel exhibited the controlled release of Zn²⁺ and BR in simulated physiological media to efficiently eliminated ROS and inhibited inflammation and resulted in a promising antibacterial effect. In vivo experiments further proved that BZ-Gel significantly inhibited the inflammatory response and enhanced collagen deposition, as well as to re-epithelialize the skin wound to ultimately promote wound healing in diabetic mice. Our results indicate that the ROS-responsive hydrogel coupled with BR@Zn-BTB synergistically promotes diabetic wound healing.

Eco-friendly cellulose-based hydrogel functionalized by NIR-responsive multimodal antibacterial polymeric ionic liquid as platform for promoting wound healing

With the trend of sustainable development and the complex medical environment, there is a strong demand for multimodal antibacterial cellulose wound dressing (MACD) with photothermal therapy (PTT). Herein, a novel MACD fabrication strategy with PTT was proposed and implemented through graft polymerization of an imidazolium ionic liquid monomer containing iron complex anion structure. The fabricated hydrogels exhibited excellent antibacterial properties because of the efficient photothermal conversion ability (68.67 %) of ionic liquids and the intrinsic structural characteristic of quaternary ammonium salts. The antibacterial ratio of cellulosic hydrogel dressings to S. aureus and E. coli could reach 99.57 % and 99.16 %, respectively. Additionally, the fabricated hydrogels demonstrated extremely low hemolysis rates (<5 %) and excellent cell viability (~>85 %). Furthermore, in vivo antibacterial experimental results proved that the fabricated antibacterial dressings could significantly accelerate wound healing. Therefore, the proposed strategy would provide a new method of designing and preparing high-performance cellulose wound dressings.

Application of polyvinyl alcohol/chitosan copolymer hydrogels in biomedicine: A review

Hydrogels is a hydrophilic, cross-linked polymer of three-dimensional network structures. The application of hydrogels prepared from a single polymer in the biomedical field has many drawbacks. The functional blend of polyvinyl alcohol and chitosan allows hydrogels to have better and more desirable properties than those produced from a single polymer, which is a good biomaterial for development and design. In this paper, we have reviewed the progress in the application of polyvinyl alcohol/chitosan composite hydrogels in various medical fields, the different cross-linking agents and cross-linking methods, and the research progress in the optimization of composite hydrogels for their subsequent wide range of biomedical applications.

Synthesis, Characterization, Properties, and Biomedical Application of Chitosan-Based Hydrogels

The prospective applications of chitosan-based hydrogels (CBHs), a category of biocompatible and biodegradable materials, in biomedical disciplines such as tissue engineering, wound healing, drug delivery, and biosensing have garnered great interest. The synthesis and characterization processes used to create CBHs play a significant role in determining their characteristics and effectiveness. The qualities of CBHs might be greatly influenced by tailoring the manufacturing method to get certain traits, including porosity, swelling, mechanical strength, and bioactivity. Additionally, characterization methods aid in gaining access to the microstructures and properties of CBHs. Herein, this review provides a comprehensive assessment of the state-of-the-art with a focus on the affiliation between particular properties and domains in biomedicine. Moreover, this review highlights the beneficial properties and wide application of stimuli-responsive CBHs. The main obstacles and prospects for the future of CBH development for biomedical applications are also covered in this review.

Polyacrylamide Hydrogel Containing Calendula Extract as a Wound Healing Bandage: In Vivo Test

Hydrogel is a biomaterial widely used in several areas of industry due to its great biocompatibility and adaptability to biological tissues. In Brazil, the Calendula plant is approved by the Ministry of Health as a medicinal herb. It was chosen to be incorporated in the hydrogel formulation because of its anti-inflammatory, antiseptic and healing effects. This study synthesized polyacrylamide hydrogel containing calendula extract and evaluated its efficiency as a bandage for wound healing. The hydrogels were prepared using free radical polymerization and characterized by Scanning Electron Microscopy, swelling analysis and mechanical properties by texturometer. The morphology of the matrices showed large pores and foliaceous structure. In vivo testing, as well as the evaluation of acute dermal toxicity, was conducted using male Wistar rats. The tests indicated efficient collagen fiber production, improved skin repair and no signs of dermal toxicity. Thus, the hydrogel presents compatible properties for the controlled release of calendula extract used as a bandage to promote cicatrization.

Incorporation of Saqez essential oil into polyvinyl alcohol/chitosan bilayer hydrogel as a potent wound dressing material

Nowadays, many studies are conducted on multilayer hydrogels for wound dressing. On the other hand, considering the emergence of bacterial resistance to common antibiotics, studies on the use of natural essential oils and their derivatives that have antibacterial and antioxidant activity can be useful. Herein, a novel bilayer hydrogel developed from polyvinyl alcohol and chitosan with the incorporation of Saqez essential oil (SEO) was synthesized. The results showed a gel-type structure with specific compression and flexibility, while the microscopic images confirmed the formation of a bilayer hydrogel. Further, the data showed that increasing the concentration of SEO reduces the swelling and water vapor permeability and increases the water retention and hydrophobicity of the hydrogel surface. The effects of the combination of SEO in the bilayer hydrogel led to a strong antioxidant property and increased antimicrobial activity. Also, the in vitro results demonstrated that the bilayer hydrogels are biocompatible, non-toxic, and blood compatible. Finally, the results of the in vivo tests showed that these bilayer hydrogels had good homeostatic efficiency. Overall, the obtained results indicate that these bilayer hydrogels are promising candidates for wound dressing.

Antimicrobial Natural Hydrogels in Biomedicine: Properties, Applications, and Challenges-A Concise Review

Natural hydrogels are widely used as biomedical materials in many areas, including drug delivery, tissue scaffolds, and particularly wound dressings, where they can act as an antimicrobial factor lowering the risk of microbial infections, which are serious health problems, especially with respect to wound healing. In this review article, a number of promising strategies in the development of hydrogels with biocidal properties, particularly those originating from natural polymers, are briefly summarized and concisely discussed. Common strategies to design and fabricate hydrogels with intrinsic or stimuli-triggered antibacterial activity are exemplified, and the mechanisms lying behind these properties are also discussed. Finally, practical antibacterial applications are also considered while discussing the current challenges and perspectives.

Renewable marine polysaccharides for microenvironment-responsive wound healing

Marine polysaccharides (MPs) are an eco-friendly and renewable resource with a distinctive set of biological functions and are regarded as biological materials that can be in contact with tissues and body fluids for an extended time and promote tissue or organ regeneration. Skin tissue is easily invaded by the external environment due to its softness and large surface area. However, the body's natural physiological healing process is often too slow or suffers from the incomplete restoration of skin structure and function. Functional wound dressings are crucial for skin tissue engineering. Herein, popular MPs from different sources are summarized systematically. In particular, the structure-effectiveness of MP-based wound dressings and the physiological remodeling process of different wounds are reviewed in detail. Finally, the prospect of MP-based smart wound dressings is stated in conjunction with the wound microenvironment and provides new opportunities for high-value biomedical applications of MPs.

Biodegradable Sodium Alginate/Carrageenan/Cellulose Composite Hydrogel Wound Dressings Containing Herbal Extracts for Promoting Blood Coagulation and Wound Healing

Accelerating the coagulation process and preventing wound infection are major challenges in the wound care process. Therefore, new multifunctional wound dressings with procoagulant, antibacterial, and antioxidant properties have enormous potential for clinical application. In this work, biodegradable hydrogels containing herbal extracts are prepared for wound dressings. First, the active ingredients are extracted from Amaranthus spinosus (A. spinosus) and Rubia cordifolia (R. cordifolia) and added to the hydrogels prepared from microcrystalline cellulose (MCC), carrageenan, and sodium alginate. Then the composite hydrogels are air-dried to obtain the wound dressings. The wound dressings prepared in this work have good biocompatibility and moisture retention. The mechanical properties of the wound dressings are further improved with the addition of MCC. Besides, the wound dressings have excellent procoagulant, antibacterial, and antioxidant properties due to the presence of R. cordifolia extract. Overall, the most effective group of wound dressings with different ingredient formulations reduces clotting time by 75% and largely inhibits bacterial growth. The wound dressings perform well in the animal wound models to promote wound healing. These results indicate that the hydrogel wound dressings prepared in this work have great potential for medical applications.

Preparation of Hydrogels Based on Modified Pectins by Tuning Their Properties for Anti-Glioma Therapy

The extracellular matrix (ECM) of the central nervous system (CNS), characterized by low stiffness and predominance of carbohydrates on protein components, mediates limited cell proliferation and migration. Pectins are polysaccharides derived from plants and could be very promising for a tunable hydrogel design that mimics the neural ECM. Aiming to regulate gel structure and viscoelastic properties, we elaborated 10 variants of pectin-based hydrogels via tuning the concentration of the polymer and the number of free carboxyl groups expressed in the degree of esterification (DE). Viscoelastic properties of hydrogels varied in the range of 3 to 900 Pa for G' and were chosen as the first criteria for the selection of variants suitable for CNS remodeling. For extended reciprocal characterization, two pairs of hydrogels were taken to test pectins with opposite DEs close to 0% and 50%, respectively, but with a similar rheology exceeding 100 Pa (G'), which was achieved by adjusting the concentration of pectin. Hydrogel swelling properties and in vitro stability, together with structure characterization using SEM and FTIR spectroscopy, displayed some differences that may sense for biomedical application. Bioassays on C6 and U87MG glioblastoma cultures testified the potential prospects of the anti-glioma activity of hydrogels developed by decreasing cell proliferation and modulating migration but supporting the high viability of neural cells.

Synthesis and Characterization of Nylon 6,6-Polyvinyl Alcohol-Based Polyelectrolytic Membrane

This work presents the preparation and investigation of blended nylon (N)/polyvinyl alcohol (PVA)-based polyelectrolytic membranes that are modified with different concentrations of sulfuric acid (SA), chlorosulfonic acid (CSA), and sulfonated activated carbon (SAC) as a filler. Scanning electron microscopy (SEM) micrographs illustrated good membrane homogeneity, and no cracks or phase separation were detected. Chemical interaction between N, PVA, and other membrane components was confirmed by Raman scattering spectroscopy and Fourier transform infrared (FTIR). In addition, the molecular structure is verified by energy depressive X-ray (EDX). Furthermore, water and methanol uptake, gel fraction, and IEC were determined as functions of varied membrane modification components. The results revealed that increasing the portion of SA, CSA and SAC led to an increase in IEC and ionic conductivity values reached 2.12 meq/g–0.076 S/cm for (N/PVA-4.0% SA-4.0% SAC), respectively, and 2.71 meq/g–0.087 S/cm for (N/PVA-4.0% CSA-4.0% SAC), respectively, while the IEC and ionic conductivity value for non-modified N/PVA membrane was 0.02 meq/g and zero, respectively. Such results enhance the potential feasibility of modified N/PVA electrolytic membranes for fuel cell (FC) applications.

Update on Chitosan-Based Hydrogels: Preparation, Characterization, and Its Antimicrobial and Antibiofilm Applications

Chitosan is a prominent biopolymer in research for of its physicochemical properties and uses. Each year, the number of publications based on chitosan and its derivatives increases. Because of its comprehensive biological properties, including antibacterial, antioxidant, and tissue regeneration activities, chitosan and its derivatives can be used to prevent and treat soft tissue diseases. Furthermore, chitosan can be employed as a nanocarrier for therapeutic drug delivery. In this review, we will first discuss chitosan and chitosan-based hydrogel polymers. The structure, functionality, and physicochemical characteristics of chitosan-based hydrogels are addressed. Second, a variety of characterization approaches were used to analyze and validate the physicochemical characteristics of chitosan-based hydrogel materials. Finally, we discuss the antibacterial, antibiofilm, and antifungal uses of supramolecular chitosan-based hydrogels. This review study can be used as a base for future research into the production of various types of chitosan-based hydrogels in the antibacterial and antifungal fields.

Novel sulfonated poly (vinyl alcohol)/carboxy methyl cellulose/acrylamide-based hybrid polyelectrolyte membranes

Novel polyelectrolytic hybrid membranes are prepared by blending carboxy methyl cellulose (CMC)-polyvinyl alcohol (PVA)-acrylamide (AA). Succinic acid and chlorosulfonic acid (CSA) are employed as crosslinkers and modifiers, respectively. Additionally, carboxylated carbon nanotube (CCNT) and sulfonated activated carbon (SAC) as fillers are used to attain appropriate chemical and mechanical stability for use as polyelectrolyte membranes (PEM). CMC, PVA, and AA are mixed and treated with CSA, CCNT, and SAC in different concentrations. First, CMC/PVA/AA solution is modified using CSA to produce a sulfonated polymeric matrix. Second, a different amount of CCNT or SAC was added as a filler to enhance the ion exchange capacity (IEC), ionic conductivity, and chemical stability. Third, the solution is cast as polyelectrolytic membranes. Chemical interactions between CMC, PVA, AA and other membrane components were confirmed using various characterization techniques such as Raman scattering spectroscopy and Fourier Transform Infrared (FTIR). Furthermore, mechanical strength, methanol uptake, gel fraction, ion exchange capacity (IEC), proton conductivity (PC), chemical and thermal stability were determined as functions of varied membrane modification components. Results reveal that the increase of CSA, CCNT and SAC is leading to increase the IEC values reaching 1.54 mmol/g for (CMC/PVA-4% CSA), 1.74 mmol/g for (CMC/PVA-4%CSA-2%CCNT) and 2.31 mmol/g for (CMC/PVA-4% CSA-2% SAC) comparing to 0.11 mmol/g for non-modified CMC/PVA/AA membrane. Sequentially, the proton conductivity value is changed from 1 × 10^-3 S/cm in non-modified CMC/PVA/AA membrane to 0.082 S/cm for (CMC/PVA-4% CSA), 0.0984 S/cm for (CMC/PVA-4%CSA-2%CCNT) and 0.1050 S/cm for (CMC/PVA-4% CSA-2% SAC). Such results enhance the potential feasibility of modified CMC/PVA/AA hybrid as polyelectrolytic membranes.

Polysaccharide-based hydrogels for drug delivery and wound management: a review

INTRODUCTION

Polysaccharide-based hydrogels (PBHs) offer several advantages over their synthetic counterparts. Their natural origin contributes to their nontoxicity, high biocompatibility, and in vivo biodegradability. Their properties can be tuned finely to obtain hydrogels with desired mechanical, structural, and chemical properties.

AREAS COVERED

Such versatile characteristics have potentiated the use of PBHs for the delivery of drugs, vaccines, protein and peptide therapeutics, genes, cells, probiotics, bacteriophages, and other therapeutic agents. Recent advances in hydrogel-based formulations such as nanogels, microgels, microneedles, hydrogel beads, nanocarrier-loaded hydrogels, and complexation hydrogels have enabled the precise delivery of a wide range of therapeutics. This review aims to give a holistic overview of hydrogels in the delivery of a variety of therapeutics through different routes.

EXPERT OPINION

PBHs have been used to enable the oral delivery of vaccines and other biologicals, thereby allowing self-administration of life-saving vaccines during public health emergencies. There is a lack of commercialized wound dressings for the treatment of chronic wounds. PBH-based wound dressings, especially those based on chitosan and loaded with actives and growth factors, have the potential to help in the long-term treatment of such wounds. Recent developments in the 3D printing of hydrogels can enable the quick and large-scale production of drug-loaded hydrogels.

Evaluation of the Chemical, Morphological, Physical, Mechanical, and Biological Properties of Chitosan/Polyvinyl Alcohol Nanofibrous Scaffolds for Potential Use in Oral Tissue Engineering

Background Chitosan is a biocompatible, biodegradable, and non-toxic natural polymer that can be fabricated by different methods for use in dental and biomedical fields. Electrospinning can produce polymeric nanofibrous scaffolds and membranes with desirable properties for use in tissue engineering. The objectives of this study were to investigate several morphological, physical, and biological characteristics of these nanofibrous scaffolds and evaluate their potential use in tissue engineering. Methodology Chitosan/polyvinyl alcohol nanofibrous scaffolds (CS/PVA NFS) in a ratio of 70/30 were fabricated by conventional electrospinning. The scaffolds were evaluated chemically by Fourier transformed infrared spectroscopy (FTIR) and morphologically by the atomic force microscope (AFM) and the field emission-scanning electron microscope (FE-SEM). These scaffolds were also evaluated mechanically by a tensile strength test and several investigations, including water contact angle, swelling ratio, and degradation ratio. Biological evaluations included protein adsorption, cell culture, and cell viability assay. Results The morphological evaluation revealed a homogenous, bead-free mat with an average fiber diameter of 172.7 ± 56.8 nm, an average pore size of 0.54 ± 0.17 µm, and porosity of 74.8% ± 3.3%; the scaffolds showed a tensile strength of 6.67 ± 0.7 Mpa. Scaffolds showed a desired hydrophilic property, as shown by the water contact angle test with a mean angle of 29.5°, while the swelling ratio was 229%, and degradability in phosphate buffer solution after 30 days was 26.9 ± 2.9%. In-vitro cell culture study with adipose tissue mesenchymal stem cells and cell viability and cytotoxicity tests by MTT assay demonstrated well-attached cells with increasing proliferation rate with no signs of cytotoxicity. Conclusions Assessment of the CS/PVA NFS revealed randomly oriented bead-free and porous mats. The scaffolds were stable at aqueous solutions following thermal treatment. They were hydrophilic, biodegradable, and biocompatible, as shown by the cell culture and MTT assay, which suggest that the fabricated scaffolds have the potential to be used in tissue engineering applications either as scaffolds, bio-grafts, or barrier membranes.

Quercetin/Hydroxypropyl-β-Cyclodextrin Inclusion Complex-Loaded Hydrogels for Accelerated Wound Healing

This study concentrated on developing quercetin/cyclodextrin inclusion complex-loaded polyvinyl alcohol (PVA) hydrogel for enhanced stability and solubility. Quercetin was encapsulated in hydroxypropyl-β-cyclodextrin (HP-β-CD) by the solvent evaporation method. The prepared quercetin/HP-β-CD inclusion complex showed 90.50 ± 1.84% encapsulation efficiency (%EE) and 4.67 ± 0.13% loading capacity (%LC), and its successful encapsulation was confirmed by FT-IR and XRD. The quercetin/HP-β-CD inclusion complex was well dispersed in viscous solutions of PVA in various amounts (0.5, 1.0, 1.5. 2.5, and 5.0% w/v ratio), and the drug-loaded polymer solution was physically crosslinked by multiple freeze–thaw cycles to form the hydrogel. The cumulative amount of quercetin released from the prepared hydrogels increased with increasing concentrations of the inclusion complex. The introduction of the inclusion complex into the PVA hydrogels had no influence on their swelling ratio, but gelation and compressive strength reduced with increasing inclusion complex concentration. The potential cytotoxicity of quercetin/HP-β-CD inclusion complex hydrogels was evaluated by MTT assay and expressed as % cell viability. The results show biocompatibility toward NCTC 929 clone cells. The inhibitory efficacy was evaluated with 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, and the results show a higher level of antioxidant activity for quercetin/HP-β-CD inclusion complex hydrogels compared with free quercetin. The findings of our study indicate that the developed quercetin/HP-β-CD inclusion complex hydrogels possess the required properties and can be proposed as a quercetin delivery system for wound-healing applications.

Production and application of biomaterials based on polyvinyl alcohol (PVA) as wound dressing: A mini review

The development of ideal wound dressing with excellent properties, such as exudate absorption capacity, drug release control ability, and increased wound healing, is currently a major requirement for wound healing. Polyvinyl alcohol (PVA) is a biodegradable semi-crystalline synthetic polymer that has been used in the field of biotechnology such as tissue regeneration, wound dressing, and drug delivery systems. In recent years, PVA-based wound dressing materials have received considerable attention due to their excellent properties such as biodegradability, biocompatibility, non-toxicity and low cost. PVA can be used as a wound dressing material to create the necessary moist wound environment, improve the physical properties of the dressing, and increase the wound healing rates. In addition, PVA can also be mixed with other organic and inorganic materials and can be used for drug delivery and wound healing. This review article addresses the role of biomaterials based on PVA mixed with other ingredients for wound dressing. It also focuses on its recent use in wound dressings as carriers of active substances.

Hydrogels: Properties and Applications in Biomedicine

Hydrogels are crosslinked polymer chains with three-dimensional (3D) network structures, which can absorb relatively large amounts of fluid. Because of the high water content, soft structure, and porosity of hydrogels, they closely resemble living tissues. Research in recent years shows that hydrogels have been applied in various fields, such as agriculture, biomaterials, the food industry, drug delivery, tissue engineering, and regenerative medicine. Along with the underlying technology improvements of hydrogel development, hydrogels can be expected to be applied in more fields. Although not all hydrogels have good biodegradability and biocompatibility, such as synthetic hydrogels (polyvinyl alcohol, polyacrylamide, polyethylene glycol hydrogels, etc.), their biodegradability and biocompatibility can be adjusted by modification of their functional group or incorporation of natural polymers. Hence, scientists are still interested in the biomedical applications of hydrogels due to their creative adjustability for different uses. In this review, we first introduce the basic information of hydrogels, such as structure, classification, and synthesis. Then, we further describe the recent applications of hydrogels in 3D cell cultures, drug delivery, wound dressing, and tissue engineering.

Evaluation of Antimicrobial and Anti-Biofilm Formation Activities of Novel Poly(vinyl alcohol) Hydrogels Reinforced with Crosslinked Chitosan and Silver Nano-Particles

Novel hydrogels were prepared by blending chitosan and poly(vinyl alcohol), PVA, then crosslinking the resulting blends using trimellitic anhydride isothiocyanate at a concentration based on chitosan content in the blends. The weight ratios of chitosan: PVA in the blends were 1:3, 1:1, and 3:1 to produce three hydrogels symbolized as H13, H11, and H31, respectively. For a comparison, H10 was also prepared by crosslinking pure chitosan with trimellitic anhydride isothiocyanate. For further modification, three H31/silver nanocomposites (AgNPs) were synthesized using three different concentrations of silver nitrate to obtain H31/AgNPs1%, H31/AgNPs3% and H31/AgNPs5%. The structures of the prepared samples were emphasized using various analytical techniques. PVA has no inhibition activity against the tested microbes and biofilms. The antimicrobial and anti-biofilm formation activities of the investigated samples was arranged as: H31/AgNPs5% ≥ H31/AgNPs3% > H31/AgNPs1% > H10 > H31 > H11 > H13 > chitosan. H31/AgNPs5% and H31/AgNPs3% were more potent than Vancomycin and Amphotericin B against most of the tested microbes. Interestingly, H31 and H31/AgNPs3% were safe on the normal human cells. Consequently, hydrogels resulting from crosslinked blends of chitosan and PVA loaded with AgNPs in the same structure have significantly reinforced the antimicrobial and inhibition activity against the biofilms of PVA.

Polysaccharide hydrogels regulate macrophage polarization and enhance the anti-tumor efficacy of melanoma

Chemotherapy occupies a prominent position in combination treatments of melanoma. However, the severe systemic side effects and the pro-tumorigenic microenvironment limited its therapeutic efficacy. In the present study, polysaccharide hydrogels (SCOD) were constructed by N-succinyl chitosan and oxidized dextran through Schiff-base formation to deliver doxorubicin (Dox) locally. The gelation time and mechanical properties of SCOD hydrogels could be fine-tuned by varying concentration of precursor solutions. Rheological data revealed that SCOD hydrogels possessed injectable shear-shinning property and remarkable self-healing capability. It also could be degraded by lysozyme widely present in body fluids. Moreover, SCOD hydrogels were readily loaded with Dox in precursor solutions and released drug over 1 week in a pH-dependent manner. The ability of Dox-loaded SCOD hydrogels to inhibit the growth of murine B16 and human A375 melanoma was verified by in vitro assays. Strikingly, Dox-loaded SCOD hydrogels were found to efficiently induce polarization of tumor-associated macrophages towards M1 phenotype that favors an anti-tumorigenic tumor microenvironment. Notably, in vivo experiments demonstrated that locally injected Dox-loaded SCOD hydrogels exhibited excellent anti-tumor activity against B16 melanoma, outperforming Dox at equivalent doses administrated intravenously. Therefore, the injectable and self-healing polysaccharide hydrogels are a promising strategy to improve locoregional control in melanoma.

Preparation and characterization of succinyl chitosan and succinyl chitosan nanoparticle film: In vitro and in vivo evaluation of wound healing activity

Development of novel wound dressing materials having the ability to prevent bacterial infections and capable of accelerating the tissue regeneration process is utmost important, since the wounds in patients can cause severe health issues. In the present work, we synthesized novel N-succinyl chitosan nanoparticles (N-SuC NPs) films and tested their antimicrobial, cytotoxicity, and in vitro and in vivo wound healing activity. N-SuC NPs were synthesized by ionic gelation method, and subsequently N-SuC NPs films were prepared by solution casting method using synthesized N-SuC NPs. The prepared N-SuC NPs films showed significant antimicrobial activity against Escherichia coli and Staphylococcus aureus with a minimum inhibitory concentration of 6 mg/mL and <8 mg/mL, respectively. The biocompatibility and the in vitro wound healing activity of N-SuC NPs films were analyzed using human dermal fibroblast (HDF) cells. In vivo cutaneous wound healing of the N-SuC NPs film was investigated using the Wister rat model, and the studies showed that the N-SuC NPs film significantly accelerated the wound healing process by inducing more blood vessels formation and tissue granulation. The experimental results showed that synthesized N-SuC NPs film had excellent antimicrobial, cytotoxicity and wound healing activity, indicating that it could be used in biomedical applications.

Synergistic Effect of Glycyrrhizic Acid and ZnO/Palygorskite on Improving Chitosan-Based Films and Their Potential Application in Wound Healing

The synergistic effect of chitosan (CS), glycyrrhizic acid (GA) and ZnO/palygorskite (ZnO/PAL) as potential wound dressing was evaluated in the form of films by the solution casting method. The nanocomposite films were well-characterized with ATR-FTIR, XRD and SEM to explore the interactions between CS, GA and ZnO/PAL. Physical, mechanical and antibacterial properties of the nanocomposite films were systematically investigated for their reliability in end-up utilization. Importantly, it was found that the presence of PAL in the films provided enhanced mechanical properties, whereas CS, GA and ZnO supplied a broad-spectrum antibacterial activity, especially for drug-resistant bacteria such as ESBL-E. coli and MRSA. Overall, this research demonstrated that the prepared films can be a promising candidate for wound-care materials.

Succinylation of Polyallylamine: Influence on Biological Efficacy and the Formation of Electrospun Fibers

Succinylation of proteins is a commonly encountered reaction in biology and introduces negatively charged carboxylates on previously basic primary amine groups of amino acid residues. In analogy, this work investigates the succinylation of primary amines of the synthetic polyelectrolyte polyallylamine (PAA). It investigates the influence of the degree of succinylation on the cytotoxicity and antibacterial activity of the resulting polymers. Succinylation was performed in water with varying amounts of succinic anhydride and at different pH values. The PAA derivatives were analyzed in detail with respect to molecular structure using nuclear magnetic resonance and infrared absorbance spectroscopy. Polyelectrolyte and potentiometric charge titrations were used to elucidate charge ratios between primary amines and carboxylates in the polymers. The obtained materials were then evaluated with respect to their minimum inhibitory concentration against Staphylococcus aureus and Pseudomonas aeruginosa. The biocompatibility was assessed using mouse L929 fibroblasts. The degree of succinylation decreased cytotoxicity but more significantly reduced antibacterial efficacy, demonstrating the sensitivity of the fibroblast cells against this type of ampholytic polyelectrolytes. The obtained polymers were finally electrospun into microfiber webs in combination with neutral water-soluble polyvinyl alcohol. The resulting non-woven could have the potential to be used as wound dressing materials or coatings.

Starch Solutions Prepared under Different Conditions as Modifiers of Chitosan/Poly(aspartic acid)-Based Hydrogels

Recently, there has been great interest in the application of polysaccharides in the preparation of diverse biomaterials which result from their biocompatibility, biodegradability and biological activity. In this work, the investigations on chitosan/poly(aspartic acid)-based hydrogels modified with starch were described. Firstly, a series of hydrogel matrices was prepared and investigated to characterize their swelling properties, structure via FT-IR spectroscopy, elasticity and tensile strength using the Brookfield texture analyzer as well as their impact on simulated physiological liquids. Hydrogels consisting of chitosan and poly(aspartic acid) in a 2:1 volume ratio were elastic (9% elongation), did not degrade after 30-day incubation in simulated physiological liquids, exhibited a relative biocompatibility towards these liquids and similar swelling in each absorbed medium. This hydrogel matrix was modified with starch wherein two of its form were applied-a solution obtained at an elevated temperature and a suspension obtained at room temperature. Hydrogels modified with hot starch solution showed higher sorption that unmodified materials. This was probably due to the higher starch inclusion (i.e., a larger number of hydrophilic groups able to interact with the adsorbed liquid) when this polysaccharide was given in the form of a hot solution. Hydrogels modified with a cold starch suspension had visible heterogeneous inequalities on their surfaces and this modification led to the obtainment materials with unrepeatable structures which made the analysis of their properties difficult and may have led to misleading conclusions.

Bioactivity of Chitosan-Based Particles Loaded with Plant-Derived Extracts for Biomedical Applications: Emphasis on Antimicrobial Fiber-Based Systems

Marine-derived chitosan (CS) is a cationic polysaccharide widely studied for its bioactivity, which is mostly attached to its primary amine groups. CS is able to neutralize reactive oxygen species (ROS) from the microenvironments in which it is integrated, consequently reducing cell-induced oxidative stress. It also acts as a bacterial peripheral layer hindering nutrient intake and interacting with negatively charged outer cellular components, which lead to an increase in the cell permeability or to its lysis. Its biocompatibility, biodegradability, ease of processability (particularly in mild conditions), and chemical versatility has fueled CS study as a valuable matrix component of bioactive small-scaled organic drug-delivery systems, with current research also showcasing CS’s potential within tridimensional sponges, hydrogels and sutures, blended films, nanofiber sheets and fabric coatings. On the other hand, renewable plant-derived extracts are here emphasized, given their potential as eco-friendly radical scavengers, microbicidal agents, or alternatives to antibiotics, considering that most of the latter have induced bacterial resistance because of excessive and/or inappropriate use. Loading them into small-scaled particles potentiates a strong and sustained bioactivity, and a controlled release, using lower doses of bioactive compounds. A pH-triggered release, dependent on CS’s protonation/deprotonation of its amine groups, has been the most explored stimulus for that control. However, the use of CS derivatives, crosslinking agents, and/or additional stabilization processes is enabling slower release rates, following extract diffusion from the particle matrix, which can find major applicability in fiber-based systems within ROS-enriched microenvironments and/or spiked with microbes. Research on this is still in its infancy. Yet, the few published studies have already revealed that the composition, along with an adequate drug release rate, has an important role in controlling an existing infection, forming new tissue, and successfully closing a wound. A bioactive finishing of textiles has also been promoting high particle infiltration, superior washing durability, and biological response.