Hydrogels For Drug Delivery Research Articles

A pH-responsive dual-network biopolysaccharide hydrogel with enhanced self-healing and controlled drug release properties.

Traditional hydrogels based on Schiff base reactions frequently encounter issues with rapid drug release when employed as drug delivery systems owing to their susceptibility to hydrolysis under acidic conditions. It is, therefore, necessary to implement improvements to regulate the drug release behavior. In this study, a dual-network and pH-responsive biopolysaccharide hydrogel was developed, which is self-healing, injectable and biocompatible. Most importantly, the hydrogel has excellent tunability for controlled drug release. The hydrogel consisted of a primary network of dibenzaldehyde-functionalized poly(ethylene glycol) (DP) and chitosan (CS) formed through a Schiff base reaction and a secondary network of sodium alginate (SA) and CS formed through electrostatic interactions. It was found that the DP-CS-2%SA hydrogel can prolong the release duration up to four-fold compared to the single-network DP-CS hydrogel at a given release threshold. Significantly, by adjusting the relationship between the two effects through the amount of SA, the release modifiability of drug delivery systems has been greatly enhanced. This study could significantly enhance the tunability of hydrogel drug delivery systems.

Innovative Nanocomposites for Drug Delivery: A Novel Approach for Diabetic Foot Ulcer.

Diabetic Foot Ulcer (DFU) is a chronic wound, and a person with diabetes has an increased lifetime risk of foot ulcers (19%-34%) and high morbidity (65% recurrence in 3-5 years, 20% lifetime amputation). Recent data have shown rising amputation rates, especially in the younger and minority populations. This abstract discusses innovative approaches for addressing this issue. This highlights the use of nanotechnology-based drug nanocomposite systems for natural wound healing therapies, with a focus on nanoparticles, nano-emulsions, and nanogels. This review also emphasizes the potential of hydrogels for drug delivery, highlighting their versatility in various medical applications. Furthermore, it delves into the use of silver nanoparticles (AgNP's) for treating diabetic wounds while acknowledging the need to address potential toxicity concerns. Finally, the abstract discusses the utilization of traditional herbal medicine and the integration of modern science to advance wound care, particularly focusing on wound microbiome, immune response, and controlled herbal medicine delivery. This study also highlights clinical trials conducted on DFU. Overall, these abstracts highlight the importance of exploring diverse and innovative solutions to chronic wound management.

Responsive Hydrogel-Based Drug Delivery Platform for Osteoarthritis Treatment.

Osteoarthritis (OA) is the most prevalent chronic joint disorder and is a major cause of disability among the elderly population. The degeneration and damage of articular cartilage associated with OA can result in a diminished range of motion in joints, subsequently impacting fundamental activities such as ambulation, standing, and grasping objects. In severe cases, it may culminate in disability. Traditional pharmacological treatments are often accompanied by various side effects, while invasive surgical procedures increase the risk of infection and thrombosis. Consequently, identifying alternative new methods for OA treatment remains a formidable challenge. With advancements in responsive hydrogel drug delivery platforms, an increasing number of strategies have emerged to enhance OA treatment protocols. Injectable response hydrogel drug delivery platforms show many advantages in treating OA, including improved biocompatibility, prolonged drug release duration, elevated drug loading capacity and enhanced sensitivity. This article reviews the recent progress of injectable responsive hydrogel drug delivery platform for OA treatment over the past few years. These innovative methodologies present new strategies and directions for future OA treatment while summarizing a series of challenges faced during the clinical transformation of injectable response hydrogel drug delivery platforms. Overall, injectable responsive hydrogel drug delivery platforms show great potential in treating OA, especially regarding improving drug retention time and stimulus-responsive release at the lesion sites. These innovative methods provide new hope for future OA treatment and point the way for clinical applications.

Adhesive lipophilic gels delivering rapamycin prevent oral leukoplakia from malignant transformation

Oral leukoplakia (OLK) is the most emblematic oral potentially malignant disorder that may precede the diagnosis of oral squamous cell carcinoma (OSCC) and has an overall malignant transformation rate of 9.8 %. Early intervention is crucial to reduce the malignant transformation rate from OLK to OSCC but the lack of effective local pharmaceutical preparations poses a challenge to clinical management. Rapamycin is speculated to prevent OLK from carcinogenesis and its inherent lipophilicity facilitates its penetration into stratum corneum. Nevertheless, hydrophilic hydrogels frequently encounter challenges when attempting to deliver lipophilic drugs. Furthermore, the oral cavity presents a complex environment defined by oral motor functions, saliva secretion cycles, dynamic fluctuations, and protective barriers comprising mucus and lipid layers. Consequently, addressing issues of muco-penetration and muco-adhesion is imperative for developing an effective drug delivery system aiming at delivering rapamycin to target oral potentially malignant disorders.Here, a dual-function hydrogel drug delivery system integrating adhesion and lipophilicity was successfully developed based on polyvinyl alcohol (PVA) and dioleoyl phosphatidylglycerol (DOPG) via dynamic boronic ester bonds. Rheological experiments based on orthogonal design revealed that PVA-DOPG hydrogels exhibited ideal adhesive strength (around 6 kPa) and could adhere to various surfaces in both dry and wet conditions. PVA-DOPG hydrogels also significantly promoted lipophilic molecules’ penetration into stratum corneum (integrated fluorescence density of 6.95 ± 0.52 × 106 and mean fluorescence depth of 0.96 ± 0.07 mm) of ex-vivo porcine buccal mucosa (p < 0.001). Furthermore, PVA-DOPG hydrogels incorporating rapamycin inhibited malignant transformation of OLK mouse model induced by 4-Nitroquinoline N-oxide (4-NQO), distinct improvements in survival (the neoplasm incidence density at the 40th day is 0.0091) (p < 0.05), decrease in neoplasm incidence density of 36.36 % and inhibition rate in neoplasm volume of 75.04 ± 33.67 % have been demonstrated, suggesting the hydrogels were valuable candidates for potential applications in the management of OLK.

Thermosensitive Hydrogels as Targeted and Controlled Drug Delivery Systems: Potential Applications in Transplantation.

Drug delivery in transplantation plays a vital role in promoting graft survival, preventing rejection, managing complications, and contributing to positive patient outcomes. Targeted and controlled drug delivery can minimize systemic effects. Thermosensitive hydrogels, due to their unique sol-gel transition properties triggered by thermo-stimuli, have attracted significant research interest as a potential drug delivery system in transplantation. This review describes the current status, characteristics, and recent applications of thermosensitive hydrogels for drug delivery. Studies aimed at improving allotransplantation outcomes using thermosensitive hydrogels are then elaborated on. Finally, the challenges and opportunities associated with their use are discussed. Understanding the progress of research will serve as a guide for future improvements in their application as a means of targeted and controlled drug delivery in translational therapeutic applications for transplantation.

Hydrogel and Microgel Collaboration for Spatiotemporal Delivery of Biofactors to Awaken Nucleus Pulposus-Derived Stem Cells for Endogenous Repair of Disc.

Depletion of nucleus pulposus-derived stem cells (NPSCs) is a major contributing factor to the attenuation of endogenous regenerative capacity in intervertebral disc degeneration (IVDD). Introducing a hydrogel drug delivery system is a potential strategy for counteracting endogenous cell depletion. The present study proposes a delivery platform for the spatiotemporal release of multiple drugs by combining sodium alginate hydrogels with gelatin microgels (SCGP hydrogels). The SCGP hydrogels facilitated the initial release of chondroitin sulfate (ChS) and the gradual release of an independently developed parathyroid hormone-related peptide (P2). The combined action of these two small molecule drugs "awakened" the reserve NPSCs, mitigated cell damage induced by H2O2, significantly enhanced their biological activity, and promoted their differentiation toward nucleus pulposus cells. The mechanical and viscoelastic properties of the hydrogel are enhanced by physical and chemical dual cross-linking to adapt to the loading environment of the degenerated disc. A rat IVDD model is used to validate that the SCGP hydrogel can significantly inhibit the progression of IVDD and stimulate the endogenous repair of IVDD. Therefore, the spatiotemporal differential drug delivery system of the SCGP hydrogel holds promise as a convenient and efficacious therapeutic strategy for minimally invasive IVDD treatment.

Ascorbyl palmitate nanofiber-reinforced hydrogels for drug delivery in soft tissues

Nanofiber-based hydrogel delivery systems have recently shown great potential in biomedical applications, specifically due to their high surface-to-volume ratio of ultra-fine nanofibers and their ability to carry low solubility drugs. Herein, we introduce a visible light-triggered in situ-gelling drug vehicle (GAP Gel) composed of ascorbyl palmitate (AP) nanofibers and gelatin methacryloyl polymer. AP nanofibers form self-assembled structures through intermolecular interactions with a hydrophobic drug-loading core. We demonstrate that the hydrophilic periphery of AP nanofibers allows them to interact with other hydrophilic molecules via hydrogen bonds. The presence of AP nanofibers significantly enhances the viscoelasticity of GAP Gel in a concentration-dependent manner. Further, GAP Gel shows in vitro biocompatibility and sustained drug delivery efficacy when loaded with a hydrophobic antibiotic. Likewise, GAP Gel shows excellent in vivo biocompatibility when implanted in immunocompetent mice in various forms. Lastly, GAP Gels maintain cell viability when cultured in a 3D-environment over 7 days, establishing it as a promising and versatile hydrogel platform for the delivery of biotherapeutics.

Construction of an intelligent pH-sensitive hydrogel drug delivery system and its application in gastric ulcer treatment

The occurrence of gastric ulcer is mainly due to the damage of gastric mucosa which leads to inward flow of gastric acid to corrode the gastric cavity, thus producing gastric fever, vomiting, loss of appetite and other adverse reactions. Prevention and treatment of such injuries are crucial. In this study, a simple and non-toxic composite hydrogel (PLGA/CMCS) was prepared through Schiff base reaction between poly(lactic-co-glycolic acid) (PLGA) and carboxymethyl cellulose (CMCS). Subsequently, compound 1 was loaded onto it to construct PLGA/CMCS@1. A series of structural characterization and performance experiments were conducted on these novel hydrogel polymers. Furthermore, we detected the gene expression level of Fas/FasL apoptotic pathway after treating the cells with different concentrations of PLGA/CMCS@1 through an ethanol-induced damaged gastric mucosal epithelial cell model. The results showed that the system was able to significantly regulate the expression of genes related to the apoptotic pathway. The system can regulate the Fas/FasL apoptosis pathway to treat gastric ulcer.

Protein hydrogels for biomedical applications

AbstractHydrogels, characterised as highly hydrophilic three‐dimensional polymer networks, have gained increasing attention due to their unique physicochemical properties, finding applications in various fields. Natural polymer hydrogels exhibit higher biocompatibility and biodegradability compared to traditional synthetic polymer hydrogels. Proteins, being the principal materials of natural polymer hydrogels, bear numerous modifiable functional groups. The resultant hydrogel possesses responsiveness, adjustable degradability, and underway as an excellent biomaterial. Seven common raw materials used to construct protein hydrogels are introduced. In terms of comparing natural polymer hydrogels with traditional synthetic polymer hydrogels, the authors conduct a detailed analysis and comparison, highlighting the advantages of natural polymer hydrogels in terms of biocompatibility and biodegradability, and summarising their characteristics. The authors also address the limitations of various protein hydrogels and list existing strengthening cross‐linking strategies, proposing new insights to overcome the application limits of protein hydrogels. Additionally, the applications of protein hydrogels in drug delivery, biosensing, bio‐inks and tissue engineering are discussed. The authors conclude by summarising the current challenges faced by protein hydrogels and prospecting its future development.

Advancing Ovarian Cancer Therapeutics: The Role of Targeted Drug Delivery Systems.

Ovarian cancer (OC) is the most lethal reproductive system cancer and a leading cause of cancer-related death. The high mortality rate and poor prognosis of OC are primarily due to its tendency for extensive abdominal metastasis, late diagnosis in advanced stages, an immunosuppressive tumor microenvironment, significant adverse reactions to first-line chemotherapy, and the development of chemoresistance. Current adjuvant chemotherapies face challenges such as poor targeting, low efficacy, and significant side effects. Targeted drug delivery systems (TDDSs) are designed to deliver drugs precisely to the tumor site to enhance efficacy and minimize side effects. This review highlights recent advancements in the use of TDDSs for OC therapies, including drug conjugate delivery systems, nanoparticle drug delivery systems, and hydrogel drug delivery systems. The focus is on employing TDDS to conduct direct, effective, and safer interventions in OC through methods such as targeted tumor recognition and controlled drug release, either independently or in combination. This review also discusses the prospects and challenges for further development of TDDSs. Undoubtedly, the use of TDDSs shows promise in the battle against OCs.

Fungal Enzyme-Responsive Hydrogel Drug Delivery Platform for Triggered Antifungal Release.

Fungal infections can lead to debilitating consequences if they are not treated effectively. Antifungal drugs used to treat these infections can be toxic and overuse contributes to growing antifungal resistance. Candida spp., particularly C. albicans, are implicated in a majority of these infections. Virulent C. albicans produce secreted aspartic proteases (Saps) that aid in pathogen tissue invasion and proliferation at an infected site. Here, fungi-responsive hydrogels are developed that degrade in the presence of Saps to provide a triggered release of encapsulated liposomal antifungals. The hydrogel backbone incorporates a Sap-cleavable peptide sequence enabling Sap-responsive degradation. Hydrogels are found to effectively degrade in the presence of Saps extracted from C. albicans. Encapsulated liposomal antifungals show similar release kinetics as hydrogel degradation products in the presence of Saps, supporting a degradation-dependent release mechanism. Antifungal liposome-loaded responsive hydrogels exhibit successful eradication of C. albicans cultures and remain stable in sterile murine wound fluid. Finally, no significant cytotoxicity is observed for murine fibroblast cells and red blood cells exposed to hydrogel degradation products. These fungi-responsive hydrogels have the potential to be used for local, on-demand delivery of antifungal drugs, for effective treatment of fungal infections while helping to limit unnecessary exposure to thesetherapeutics.

Alginate/methacrylic acid/calcium ion-based pH-sensitive drug delivery hydrogel for the treatment of ulcerative colitis

Oral colon-targeted drug formulations play a pivotal role in managing colon diseases, yet the effectiveness of most hydrophobic drug formulations in reaching the colon orally is hindered by challenges such as poor solubility, premature release in the stomach, and low bioavailability. In this study, we devised a pH-sensitive dual-network hydrogel utilizing sodium alginate and methacrylic acid for treating ulcerative colitis. The primary rigid network layer is activated thermally through free radicals, while the secondary flexible network layer is formed by the coordination of alginic acid and calcium ions. Sulfadiazine was loaded into the hydrogels using a solution displacement method. We conducted a comprehensive analysis of the morphology, mechanical properties, and drug release mechanisms of the hydrogels. The hydrogel demonstrated outstanding pH-responsive swelling properties. In acidic environments, protonation of carboxyl groups led to hydrogel network contraction, while in weakly alkaline environments, deprotonation induced electrostatic repulsion, facilitating swelling and controlled drug release. The alteration of pH from 1.2 to 7.4 increased the drug release rate from 33 % to 92 %, aligning with the first-order kinetic release model. The drug-loaded gel exhibited a compressive stress of 0.13 MPa at 50 % strain, and its superior mechanical properties ensured stability before drug release. Moreover, the hydrogel displayed excellent biocompatibility, hemocompatibility, and thermal stability. In summary, these findings underscore the substantial potential of drug-loaded gels in advancing controlled drug delivery systems.

Self-Healing Hydrogel Resulting from the Noncovalent Interaction between Ropivacaine and Low-Molecular-Weight Gelator Sodium Deoxycholate Achieves Stable and Endurable Local Analgesia in Vivo.

Regional analgesia based on the local anesthetic ropivacaine plays a crucial role in postoperative pain management and recovery; however, the short duration of analgesia limits its clinical potential. Various drug delivery systems such as microparticles and lipid carriers have been used to prolong the analgesic effect, yet most of them are prone to abrupt release from the site of administration or have poor analgesic effects of less than 48 h, which fail to meet the needs of postoperative analgesia. In this study, a low-molecular-weight gelator sodium deoxycholate-based hydrogel loaded with ropivacaine (DC-ROP gel) was designed for long-acting analgesia. The noncovalent interaction between ropivacaine and sodium deoxycholate helps to improve the stability and sustained release performance of the gel. This internal drug-binding hydrogel also avoids experiencing the burst release effect commonly seen in polymer hydrogels previously reported for the slow release of local anesthetics. DC-ROP gel exhibited the dual advantages of self-healing after compression and long-term controlled release. In mice with inflammatory pain, DC-ROP gel achieved peripheral nerve block for more than 1 week after a single injection. Histological and blood biochemical analyses confirmed that the DC-ROP gel did not produce systemic toxicity, and cytotoxicity experiments demonstrated that the DC-ROP gel resulted in low irritation. These results suggest that DC-ROP gel provides a promising strategy for local anesthetics in long-term postoperative pain management, broadening the potential of bile salt-based low-molecular-weight hydrogels for drug delivery.

A review of recent advances in drug loading, mathematical modeling and applications of hydrogel drug delivery systems

A review of recent advances in drug loading, mathematical modeling and applications of hydrogel drug delivery systems

Development and Applications of PLGA Hydrogels for Sustained Delivery of Therapeutic Agents.

Poly(lactic-co-glycolic acid) (PLGA) hydrogels are highly utilized in biomedical research due to their biocompatibility, biodegradability, and other versatile properties. This review comprehensively explores their synthesis, properties, sustained release mechanisms, and applications in drug delivery. The introduction underscores the significance of PLGA hydrogels in addressing challenges like short half-lives and systemic toxicity in conventional drug formulations. Synthesis methods, including emulsion solvent evaporation, solvent casting, electrospinning, thermal gelation, and photopolymerization, are described in detail and their role in tailoring hydrogel properties for specific applications is highlighted. Sustained release mechanisms-such as diffusion-controlled, degradation-controlled, swelling-controlled, and combined systems-are analyzed alongside key kinetic models (zero-order, first-order, Higuchi, and Peppas models) for designing controlled drug delivery systems. Applications of PLGA hydrogels in drug delivery are discussed, highlighting their effectiveness in localized and sustained chemotherapy for cancer, as well as in the delivery of antibiotics and antimicrobials to combat infections. Challenges and future prospects in PLGA hydrogel research are discussed, with a focus on improving drug loading efficiency, improving release control mechanisms, and promoting clinical translation. In summary, PLGA hydrogels provide a promising platform for the sustained delivery of therapeutic agents and meet diverse biomedical requirements. Future advancements in materials science and biomedical engineering are anticipated to further optimize their efficacy and applicability in clinical settings. This review consolidates the current understanding and outlines future research directions for PLGA hydrogels, emphasizing their potential to revolutionize therapeutic delivery and improve patient outcomes.

Tracking the enzyme-response mechanism of tannic acid-embedded chitosan/γ-polyglutamic acid hydrogel

The design of enzyme-response hydrogels has attracted increasing interest in cell therapy, biomedical research, and tissue engineering. Their rational design usually depends on the enzyme-response mechanism and have focused on behavior improvement, drug delivery, and state transition of hydrogels. However, no enzyme-response mechanism has yet been systematically investigated. Here, we construct a tunable platform of tannic acid-embedded chitosan/γ-polyglutamic acid hydrogel to study the enzyme-response mechanism. We track the roles of gallic acid hydrolyzed from tannic acid in altering the structure and properties of the hydrogel to get insights into the mechanism. The gallic acid inside the hydrogel enhances hydrogel crosslinking, increasing the mechanical properties and pH sensitivity but reducing thickness, porosity, and swelling behavior. The gallic acid outside the hydrogel increases the positive potential and superficial hydrophobicity of the hydrogel. These findings will aid the rational design of other enzyme-response hydrogels in more extensive self-adaptive fields.

Fabrication and characterization of prednisolone-loaded chitosan and oxidized sodium alginate hydrogel for drug delivery and its biological applications

Fabrication and characterization of prednisolone-loaded chitosan and oxidized sodium alginate hydrogel for drug delivery and its biological applications

Harnessing chemical functionality of xylan hemicellulose towards carbohydrate polymer-based pH/magnetic dual-responsive nanocomposite hydrogel for drug delivery

This study reports a pH/magnetic dual-responsive hemicellulose-based nanocomposite hydrogel with nearly 100 % carbohydrate polymer-based and biodegradable polymer compositions for drug delivery. We synthesized pure Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) using a co-precipitation method, then engineering xylan hemicellulose (XH), acrylic acid, poly(ethylene glycol) diacrylate, and Fe3O4 to synthesize the pH/magnetic dual-responsive hydrogel (Fe3O4@XH-Gel), through graft polymerization on XH with in-situ doping Fe3O4 MNPs initiated by the ammonium persulfate/tetramethylethylenediamine redox system. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), X-ray diffractometry (XRD), scanning electron microscopy and energy dispersive spectrometer (SEM-EDS), high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET), swelling gravimetric analysis, vibrating sample magnetometer (VSM) were employed to analyze the hydrogel's chemical structures, morphologies, pH-responsive behaviors, and magnetic responsiveness characteristics, mechanical and rheological properties, as well as cytotoxicity and biodegradability. The results indicate that the Fe3O4@XH-Gel exhibited excellent dual responsiveness to pH and magnetism. Furthermore, an emphasis was placed on the in-depth analysis of the pH response mechanism. Finally, we utilized this cutting-edge hydrogel to investigate the controlled-release behavior of two model drugs, Acetylsalicylic acid and Theophylline. The hydrogel demonstrated exceptional controlled release attributes, positioning it as a potential carrier for targeted drug delivery, particularly to the gastrointestinal conditions.

Drug Release Study of Polyvinyl Alcohol-Gelatin-Montmorillonite Bionanocomposite Hydrogel Drug Delivery Systems Loaded with Clindamycin

One of the challenges facing medical science is the proper formulation of drug delivery systems for the correct transfer of active pharmaceutical ingredients to the body. Polymer and nanocomposite hydrogels have been considered ideal options in the preparation of drug delivery systems due to their proper properties, such as hydrophilicity and biocompatibility. In this, our research, described in this manuscript, the drug release from polyvinyl alcohol (PVA)-gelatin-montmorillonite (MMT) bionanocomposite hydrogel drug delivery systems loaded with clindamycin was studied. The structural and physical properties of prepared nanocomposite hydrogels were investigated using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmette-Teller (BET) analysis, gel fraction and swelling tests. The results showed that by adding MMT clay to PVA-gelatin hydrogels, the amount of gel fraction increased, and due to the decrease in the size of the pores, the amount of swelling decreased. The results of the drug release tests showed that the release rate of clindamycin was inversely related to the percentage of MMT added to the nanocomposite hydrogel. The results also showed that the shape of the drug delivery system and its dimensions affected the release rate of clindamycin. The dominant mechanism of drug release in all samples was found to be Fickian transport. Considering the favorable in-vitro drug release performance of our PVA-gelatin-MMT nanocomposite hydrogels in the release of clindamycin, it was concluded that they are suitable options for preparing practical drug delivery systems with controlled drug release ability.

Antimicrobial Hydrogels Based on Cationic Curdlan Derivatives for Biomedical Applications.

Hydrogels based on biocompatible polysaccharides with biological activity that can slowly release an active principle at the wound site represent promising alternatives to traditional wound dressing materials. In this respect, new hydrogels based on curdlan derivative with 2-hydroxypropyl dimethyl octyl ammonium groups (QCurd) and native curdlan (Curd) were obtained at room temperature by covalent cross-linking using a diepoxy cross-linking agent. The chemical structure of the QCurd/Curd hydrogels was investigated by Fourier transform infrared spectroscopy (FTIR) spectroscopy. Scanning electron microscopy (SEM) revealed well-defined regulated pores with an average diameter between 50 and 75 μm, and hydrophobic micro-domains of about 5 μm on the pore walls. The high swelling rate (21-24 gwater/ghydrogel) and low elastic modulus values (7-14 kPa) make them ideal for medical applications as wound dressings. To evaluate the possible use of the curdlan-based hydrogels as active dressings, the loading capacity and release kinetics of diclofenac, taken as a model drug, were studied under simulated physiological skin conditions. Several mathematical models have been applied to evaluate drug transport processes and to calculate the diffusion coefficients. The prepared QCurd/Curd hydrogels were found to have good antibacterial properties, showing a bacteriostatic effect after 48 h against S. aureus, MRSA, E. coli, and P. aeruginosa. The retarded drug delivery and antimicrobial properties of the new hydrogels support our hypothesis that they are candidates for the manufacture of wound dressings.