IPN based hydrogels for in-vivo wound dressings; catalytic wound healing dynamics and isothermal adsorption models

Interpenetrating network (IPN) methacrylated chitosan or methacrylated flaxseed gum based hydrogels have been utilized to make outstanding in-vivo wound dressings. The photopolymerization process was accomplished in presence of Eosin-Y photoinitiator with average exposure time of 13-14 s for gelation. Spectroscopic structural investigations of 1H NMR. ATR-FTIR, TGA, and AFM techniques were used. In-vitro hemolysis test provided evidence of no cytotoxicity in both hydrogels observed. The in-vivo wound dressings were monitored for five mice coated with each hydrogel and another uncoated five mice for control (self-healing). All measurements were performed in quintuplicate (n = 5) and expressed as mean ± SD values. In wound healing dynamics, our data confirmed that wound healing pass through two stages; hemostasis and inflammation for stage 1, and proliferation and remodeling for stage 2. It also provided evidence of 1st order kinetics with descending rate of healing. Consequently, catalytic role of hydrogels in wound healing was checked via half-life (δ) and negative change of activation energy values (ΔEa). Various isothermal adsorption models demonstrated spontaneous and high binding affinities of hydrogels. It also confirmed the two-stage healing process in presence of hydrogels. Conclusively, the outstanding properties of the two hydrogels suggest their potential applications in treating venous ulcers and diabetic wound healing dressings.

Carboxymethyl cellulose-alginate interpenetrating hydroxy ethyl methacrylate crosslinked polyvinyl alcohol reinforced hybrid hydrogel templates with improved biological performance for cardiac tissue engineering

Cardiac tissue engineering is an emerging approach for cardiac regeneration utilizing the inherent healing responses elicited by the surviving heart using biomaterial templates. In this study, we aimed to develop hydrogel scaffolds for cardiac tissue regeneration following myocardial infarction (MI). Two superabsorbent hydrogels, CAHA2A and CAHA2AP, were developed employing interpenetration chemistry. CAHA2A was constituted with alginate, carboxymethyl cellulose, (hydroxyethyl) methacrylate, and acrylic acid, where CAHA2AP was prepared by interpenetrated CAHA2A with polyvinyl alcohol. Both hydrogels displayed superior physiochemical characteristics, as determined by attenuated total reflection infrared spectroscopy spectral analysis, differential scanning calorimetry measurements, tensile testing, contact angle, water profiling, dye release, and conductivity. In vitro degradation of the hydrogels displayed acceptable weight composure and pH changes. Both hydrogels were hemocompatible, and biocompatible as evidenced by direct contact and MTT assays. The hydrogels promoted anterograde and retrograde migration as determined by the z-stack analysis using H9c2 cells grown with both gels. Additionally, the coculture of the hydrogels with swine epicardial adipose tissue cells and cardiac fibroblasts resulted in synchronous growth without any toxicity. Also, both hydrogels facilitated the production of extracellular matrix by the H9c2 cells. Overall, the findings support an appreciable in vitro performance of both hydrogels for cardiac tissue engineering applications.

Preparation and characterization of starch-cellulose interpenetrating network hydrogels based on sequential Diels-Alder click reaction and photopolymerization

Herein, starch-cellulose interpenetrating network (IPN) hydrogels were fabricated by sequential Diels-Alder click reaction and photopolymerization in water. Moreover, β-cyclodextrin, a commonly used host molecule in supramolecular chemistry, was also introduced to improve the performance of the IPN hydrogel. Firstly, the starch-based dienes were synthesized by modifying starch with N-maleoyl-β-alanine, and the cellulose-based dienophiles were obtained by the reaction of cellulose and furfurylamide succinate; Secondly, the as-synthesized starch-based dienes, cellulose-based dienophiles, polymerizable β-cyclodextrin, crosslinker, and acrylamide were dissolved in water and obtained a transparent solution. The solution was maintained in a water bath of 50 °C for 3 h, forming the first network via catalyst-free click Diels-Alder reaction, subsequently, the second network was formed by photopolymerization. Their preparation conditions were optimized via one-factor experiments and their properties and structures were characterized. Finally, 5- fluorouracil (5-Fu) was used as a model drug to study the sustained release behavior of the drug-loaded hydrogels. Release profile was found to fit in Ritger-Peppas kinetic model and polymer relaxation and drug diffusion made a valuable contribution to drug release. Taking into account the virtues of easily controllable photopolymerization and catalyst-free Diels-Alder reaction, the strategy described here has a potential application in the preparation of IPN hydrogels.

Physicochemical Interactions in Nanofunctionalized Alginate/GelMA IPN Hydrogels

Polymeric hydrogels are currently at the center of research due to their particular characteristics. They have tunable physical, chemical, and biological properties making them a material of choice for a large range of applications. Polymer-composite and nanocomposite hydrogels were developed to enhance the native hydrogel’s properties and to include numerous functionalities. In this work, alginate/gelatin-methacryloyl-based interpenetrating polymer network hydrogels were prepared with different alginate concentrations and investigated before and after the functionalization with nanoliposomes. The multiscale analysis was obtained through Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. The results show interactions between two polymers as well as between the nanoliposomes and biopolymer.

Controlled Hydration, Transition, and Drug Release Realized by Adjusting Layer Thickness in Alginate-Ca2+/poly(N-isopropylacrylamide) Interpenetrating Polymeric Network Hydrogels on Cotton Fabrics

The controlled hydration, transition, and drug release are realized by adjusting layer thickness in thermoresponsive interpenetrating polymeric network (IPN) hydrogels on cotton fabrics. IPN hydrogels are synthesized by sodium alginate (SA) and poly(N-isopropylacrylamide) (PNIPAM) with a ratio of 1:5/% (w/v). The cotton-fabric-supported IPN hydrogels with a thickness of 1000 μm exhibit a transition temperature (TT) at 35.2 °C. When the hydrogel thicknesses are thinned to 500 and 250 μm, the TTs are reduced to 34.8 and 34.1 °C, respectively. Interestingly, the morphology of IPN hydrogels switches from a well-defined honeycomb-like network structure (1000 μm) to a densely packed layer structure (250 μm). The thinner layers not only present a smaller extent of hydration and collapse but also require longer time to reach an equilibrium state, which can be attributed to the more pronounced hindrance of the chain rearrangement by the cotton fabrics. To address the influence of layer thickness on the drug release, we compare the release rate and cumulative release percentage of the test drugs tetracycline hydrochloride (TCH) and levofloxacin hydrochloride (LH) between pure IPN hydrogels and cotton-fabric-supported IPN hydrogels (250, 500, and 1000 μm) at 25 °C (below the TT) and 37 °C (above the TT). Because of the compressive stress from the collapsed hydrogels, a higher release is observed in both hydrogels when the temperature is above TT. The cotton fabric induces a slower and less prominent drug release in IPN hydrogels. Thus, combining the obtained correlation between the transition and hydrogels layer thickness, the drug release in cotton-fabric-supported IPN hydrogels can be regulated by the layer thickness, which appears especially suitable for a controlled release in wound dressing applications.

Role of active nanoliposomes in the surface and bulk mechanical properties of hybrid hydrogels

Nanoliposomes are widely used as delivery vehicles for active compounds. Nanoliposomes from rapeseed phospholipids were incorporated into interpenetrating polymer network hydrogels of gelatin methacryloyl and alginate. The multiscale physicochemical properties of the hydrogels are studied both on the surface and through the thickness of the 3D network. The obtained composite hydrogels exhibited strong mechanical properties and a highly porous surface. The blend ratio, as well as the concentration of nanoliposomes, affects the properties of the hydrogels. Nanofunctionalized hydrogels induced keratinocyte ​growth. These advantageous characteristics may open up many applications of the developed hydrogels in drug delivery and tissue engineering.