A review on polymeric hydrogel membranes for wound dressing applications: PVA-based hydrogel dressings

Gamma radiation-induced crosslinked composite membranes based on polyvinyl alcohol/chitosan/AgNO3/vitamin E for biomedical applications

This review introduces a brief description on the featured properties of polyvinyl alcohol based on hydrogel dressings. During past ten years many new artificial polymeric dressings have been developed, which meet requirements of wound healing. This review mainly focuses on one representative of ideal polymeric wound dressing membranes, polyvinyl alcohol based hydrogel dressings. But as the hydrogels with single component have low mechanical strength, recent trends have offered composite hydrogel membranes to achieve the ideal wound dressing requirements.

In this study, attapulgite clay was extracted from North Western desert of Borg El-Arab, Egypt. The pristine clay was purified and treated before further use. The mineralogical composition of pristine clay was investigated by TEM, SEM, XRD and EDX analyses. Moreover, the pristine clay was organically modified with hexadecyl trimethyl ammonium chloride before incorporating into PVA-HES membranes. The modification of clay was also verified by FTIR, SEM and XRD analyses. Meanwhile, PVA-hydroxyethyl starch (PVA-HES/modified attapulgite clay) composite hydrogel membranes were fabricated by solution-casting method, where citric acid was utilized as cross-linker for formation of cross-linked membranes. The influence of addition of Egyptian modified attapulgite clay in ratios (0, 1.0, 3.0, 5.0, 7.0 and 10 wt%) on properties of PVA-HES composite membranes was studied in detail. Results revealed that the incorporation of modified attapulgite clay into membranes increased significantly the swelling ability and mechanical stability of composed hydrogel membranes. Also, the increase in clay contents in membranes showed antimicrobial activity against tested six pathogen strains and adequate hemolytic behavior, compared to clay-free membranes. These findings are referring to the capability of using of PVA-HES–attapulgite composite membrane as a good candidate for the purpose of super-absorbent dermal wound dressings.

Gravity-driven composite cellulose acetate/activated carbon aluminium-based hydrogel membrane for landfill wastewater treatment

Poly (vinyl alcohol)-alginate physically crosslinked hydrogel membranes for wound dressing applications: Characterization and bio-evaluation

Non-conductive surfaces electro-fabrication of transparent high-performance layered chitosan-silver-montmorillonite composite hydrogels for infected wound dressing.

A hydrogel membrane was prepared using activated carbon and sodium dodecyl sulphate modified montmorillonite clay incorporated into sodium alginate polymer. The activated carbon was prepared from a locally available susbine plant. The physiochemical characteristics of the synthesized hydrogel membrane were investigated using FTIR, SEM, EDX, and TGA techniques. The performance of the membrane was evaluated as an adsorbent by methyl red adsorption from water. The adsorption behavior of the hydrogel membrane was investigated under varying conditions of pH (2-10), membrane dose (0.0025-0.015 mg g-1), equilibrium adsorption time (30-360 minutes), solution temperature (25-45 °C) and dye concentration (100-500 mg L-1). The maximum adsorption capacity of the hydrogel membrane was 248.13 mg g-1. The kinetics of methyl red adsorption on hydrogel membrane best followed the pseudo-second order (PSO). The equilibrium adsorption results suggested that it obeyed the Freundlich isotherm very closely (R2 = 0.994). The thermodynamics of methyl red adsorption on the hydrogel membrane revealed that the adsorption was spontaneous (ΔS° = 16.15 kJ K-1 mol-1), favorable (ΔG° = -3.51 kJ mol-1), and endothermic (ΔH° = -1.48 kJ mol-1) in nature. These investigations suggested that the fabricated hydrogel membrane could be suitably used for methyl red adsorption from the solution.

In situ photopolymerized hydrogel dressings create minimally invasive methods that offer advantages over the use of preformed dressings such as conformability in any wound bed, convenience of application, and improved patient compliance and comfort. Here, we report an in situ-formed hydrogel membrane through ultraviolet cross-linking of a photocross-linkable azidobenzoic hydroxypropyl chitosan aqueous solution. The hydrogel membrane is stable, flexible, and transparent, with a bulk network structure of smoothness, integrity, and density. Fluid uptake ability, water vapor transmission rate, water retention, and bioadhesion of the thus resulted hydrogel membranes (0.1 mm thick) were determined to range from 97.0-96.3%, 2,934-2,561 g/m(2)/day, 36.69-22.94% (after 6 days), and 4.8-12.3 N/cm(2), respectively. These data indicate that the hydrogel membrane can maintain a long period of moist environment over the wound bed for enhancing reepithelialization. Specifically, these properties of the hydrogel membrane were controllable to some extent, by adjusting the substitution degree of the photoreactive azide groups. The hydrogel membrane also exhibited barrier function, as it was impermeable to bacteria but permeable to oxygen. In vitro experiments using two major skin cell types (dermal fibroblast and epidermal keratinocyte) revealed the hydrogel membrane have neither cytotoxicity nor an effect on cell proliferation. Taken together, the in situ photocross-linked azidobenzoic hydroxypropyl chitosan hydrogel membrane has a great potential in the management of wound healing and skin burn.

FucoPol, a fucose-rich polyanionic polysaccharide, was used for the first time for the preparation of hydrogel membranes (HMs) using Fe3+ as a crosslinking agent. This study evaluated the impact of Fe3+ and FucoPol concentrations on the HMs' strength. The results show that, above 1.5 g/L, Fe3+ concentration had a limited influence on the HMs' strength, and varying the FucoPol concentration had a more significant effect. Three different FucoPol concentrations (1.0, 1.75 and 2.5 wt.%) were combined with Fe3+ (1.5 g/L), resulting in HMs with a water content above 97 wt.% and an Fe3+ content up to 0.16 wt.%. HMs with lower FucoPol content exhibited a denser porous microstructure as the polymer concentration increased. Moreover, the low polymer content HM presented the highest swelling ratio (22.3 ± 1.8 g/g) and a lower hardness value (32.4 ± 5.8 kPa). However, improved mechanical properties (221.9 ± 10.2 kPa) along with a decrease in the swelling ratio (11.9 ± 1.6 g/g) were obtained for HMs with a higher polymer content. Furthermore, all HMs were non-cytotoxic and revealed anti-inflammatory activity. The incorporation of FucoPol as a structuring agent and bioactive ingredient in the development of HMs opens up new possibilities for its use in tissue engineering, drug delivery and wound care management.

The purpose of the study was to synthesize and characterize a new form of topical membranes as chitosan-based hydrogel membranes for bacterial skin infections. The polymeric membranes were synthesized by modification in free radical solution polymerization technique. High molecular weight (HMW) chitosan polymer was cross-linked with monomer 2-acrylamido-2-methylpropane sulfonic acid (AMPS) through cross-linker N,N-methylenebisacrylamide (MBA). Mupirocin, an antibiotic, was used as model drug. The polymeric membranes were prepared in spherical form that found stable and elastic. Characterization of hydrogel membranes was performed by FTIR, SEM, DSC, TGA, swelling behavior, drug release, irritation study, and ex vivo drug permeation and deposition study. Structural and thermal studies confirmed the formation of new polymeric network with enhanced stability of hydrogel membranes. Permeation flux of drug from optimized formulation through rabbit's skin assessed by using Franz cell was up to 104.09μgcm-2h-1. Furthermore, hydrogel membrane has significant retention of drug in skin up to 2185μg1.5cm-2. Draize patch test confirmed the synthesized hydrogels as non-irritant to skin. The preparation of a topical membrane with improved antibacterial activity within controlled release manner is desirable for the advancement and treatment of skin diseases.

In this study, carbonic anhydrase (CA, EC 4.2.1.1) molecules were embedded into metal-organic frameworks (MOFs) via co-precipitation (CA@ZIF-8), and then these CA@ZIF-8 nanocomposites were encapsulated in the poly(vinyl alcohol) (PVA)-chitosan (CS) hydrogel networks to prepare CA@ZIF-8-PVA-CS composite hydrogels (PVA/CS/CA@ZIF-8) with high activity, stability, and reusability. The immobilization efficiency of CA was greater than 70%, suggesting the high immobilization efficiency. The prepared PVA/CS/CA@ZIF-8 composite membranes displayed excellent higher stability against a high temperature, denaturants, and acid than free CA and CA@ZIF-8. Furthermore, these membranes exhibited an excellent performance for CO2 capture. The amount of calcium carbonate obtained by PVA/CS/CA@ZIF-8 hydrogel membranes was 20- and 1.63-fold than free CA and CA@ZIF-8 composites, respectively. Furthermore, the hydrogel membranes exhibited superior reusability and mechanical strength. The hydrogel membrane maitained 50% of its original activity after 11 cycles. However, CA@ZIF-8 completely lost activity. These results indicated that the PVA/CS/CA@ZIF-8 membranes can be efficiently applied to capture CO2 sequestration.

A variety of advances have been made in the use of environmental factors to control the separation characteristics of polymeric membranes in real time. These systems work by incorporating membrane materials which respond to external stimuli such as temperature or pH by making changes in conformation, solubility, or phase. In this review we focus on the use of light (photons) as the external control stimulus. Specifically, we examine the ability to control polymeric membrane properties by incorporating reversible photochromic moieties into the polymer structure. The first section is a brief review of the chemistry of photochromic compounds, the second section focuses on photocontrol of the separation properties of nonporous and hydrogel membranes, and the third section discusses the photocontrol of release rates from synthetic bilayer membranes.

A methacrylate monomer having the phospholipid polar group, 2-methacryloyloxyethyl phosphorylcholine (MPC) was prepared by an improved method with good yield. MPC was copolymerized with n-butyl methacrylate (BMA). The polymer membranes were prepared from the poly(MPC-co-BMA) by a solution casting method. The membrane adsorbed water well and became a hydrogel structure even MPC mole fraction in the copolymer was 0.04. The water content of the hydrogel membrane increased with increase of MPC units and rise of temperature. These properties of the hydrogel membrane were attributed to the highly hydrophilic phospholipid polar group in the copolymer. Water soluble organic compounds and proteins whose molecular weights were below 104 permeated through the hydrogel membrane. However, the protein could not permeate when the molecular weight was higher than 105.

Artificial hydrogel membranes with good biocompatibility are strongly needed in biological fields. The preparation of biocompatible hydrogel membranes simultaneously possessing high mechanical strength, excellent elasticity, and satisfactory self-healing properties remains a challenge. Herein, we demonstrate the preparation of such hydrogel membranes by complexation of sulfonate-containing polyurethane (SPU) and poly(acrylic acid) (PAA) in the presence of Zn2+ ions followed by swelling in water (denoted as SPU-PAA/Zn). Originating from the synergy of the coordination and hydrogen-bonding interactions and the reinforcement effect of the in situ formed hydrophobic domains, the SPU-PAA/Zn hydrogel membrane exhibits a high tensile strength of ∼7.1 MPa and a toughness of ∼30.4 MJ m-3. Moreover, the hydrogel membrane is highly elastic, which can restore to its initial state from an ∼500% strain within 40 min rest at room temperature without any external assistance. The dynamic noncovalent interactions and hydrophobic domains allow the fractured hydrogel membrane to heal and completely regain its original integrity and mechanical properties at room temperature. Both in vitro and in vivo tests confirm that the hydrogel membrane exhibits satisfactory biocompatibility and could be potentially used as a biological barrier membrane in surgical operations or artificial organs.

We establish the regularities of formation of composite polymeric hydrogel membranes based on liquid-structured copolymers of 2-hydroxyethyl methacrylate (HEMA) with polyvinylpyrrolidone (PVP) modified by a thin layer of a mixture of polyamide-6 (PA-6) and PVP by the method of diffusion deposition from a formate solution. We study the physical and mechanical properties of the obtained composite membranes depending on the molecular weight of PVP in the structure of the copolymer and in the modifying mixture, as well as on the degree of adsorption of the PA-6–PVP mixture on the source hydrogels. It is shown that the strength of hydrogel membranes increases with the molecular weight of PVP in the hydrogel matrix structure and with its decrease in the PA-6–PVP formate solution.