This work was concerned with the fabrication of a porous hydrogel system suitable for medium to heavy-exudating wounds where traditional hydrogels cannot be used. The hydrogels were based on 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPs). In order to produce the porous structure, additional components were added (acid, blowing agent, foam stabilizer). Manuka honey (MH) was also incorporated at concentrations of 1 and 10% w/w. The hydrogel samples were characterized for morphology via scanning electron microscopy, mechanical rheology, swelling using a gravimetric method, surface absorption, and cell cytotoxicity. The results confirmed the formation of porous hydrogels (PH) with pore sizes ranging from ~50–110 µm. The swelling performance showed that the non-porous hydrogel (NPH) swelled to ~2000%, while PH weight increased ~5000%. Additionally, the use of a surface absorption technique showed that the PH absorbed 10 μL in <3000 ms, and NPH absorbed <1 μL over the same time. Incorporating MH the enhanced gel appearance and mechanical properties, including smaller pores and linear swelling. In summary, the PH produced in this study had excellent swelling performance with rapid absorption of surface liquid. Therefore, these materials have the potential to expand the applicability of hydrogels to a range of wound types, as they can both donate and absorb fluid.

This study investigated the performance of novel hydrogels based on poly (N-vinylformamide) (PNVF), copolymers of NVF with N-hydroxyethyl acrylamide (HEA) (P(NVF-co-HEA)), and 2-carboxyethyl acrylate (CEA) (P(NVF-co-CEA)), which were synthesized by photopolymerization using a UVLED light source. The hydrogels were analyzed for important properties such as equilibrium water content (%EWC), contact angle, freezing and non-freezing water, and diffusion-based in vitro release. The results showed that PNVF had an extremely high %EWC of 94.57%, while a decreasing NVF content in the copolymer hydrogels led to a decrease in water content with a linear relationship with HEA or CEA content. Water structuring in the hydrogels showed appreciably more variance, with ratios of free to bound water differing from 16.7:1 (NVF) to 1.3:1 (CEA), corresponding to PNVF having ~67 water molecules per repeat unit. The release studies of different dye molecules followed Higuchi’s model, with the amount of dye released from the hydrogels depending on the amount of free water and the structural interactions between the polymer and the molecule being released. The results suggest that PNVF copolymer hydrogels have potential for controlled drug delivery by altering the polymer composition to govern the amount and ratio of free to bound water contained in the hydrogels.

This study explores the synthesis and modification of poly(N-vinylformamide-co-N-hydroxyethyl acrylamide) (poly(NVF-co-HEA)) hydrogels for cosmetic applications. Poly(NVF-co-HEA) hydrogels were produced followed by an acid hydrolysis reaction to produce poly(NVF-co-VAm-co-HEA) hydrogels, introducing poly(vinyl amine) (PVAm) into the structure. This modification considerably alters the hydrogels’ properties, yielding materials with over 96% water content, predominantly in the form of non-freezing or free water, which is beneficial in the uptake and release of hydrophilic species. The primary amine groups from inclusion of VAm also improved the mechanical properties, as evidenced by an 8-fold increase in Young’s modulus. The hydrogels also possessed pH-responsive behavior, which was particularly noticeable under acidic and basic conditions, where a large decrease in water content was observed (40% to 75% reduction). Characterizing the hydrogels’ release capabilities involved using organic dyes of different functional groups and sizes to examine the pH impact on release. The results indicated that hydrolyzed hydrogels interacted more effectively with charged species, highlighting their suitability for pH-responsive delivery. The release of cosmetic active ingredients was also demonstrated through the controlled release of Liquid Azelaic™, specifically potassium azeloyl diglycinate (PAD). Our findings reveal that the hydrolyzed hydrogels exhibit superior burst release, especially under alkaline conditions, suggesting their suitability for cosmetic applications where controlled, pH-responsive delivery of active ingredients is desired. Overall, this investigation highlights the potential of hydrolyzed poly(NVF-co-HEA) hydrogels in cosmetic applications. Their ability to combine high water content with mechanical integrity, along with their pH-responsive release ability, allows for use in cosmetic formulations.

This study investigates hydrogels based on 2-Acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) copolymers, incorporating N-hydroxyethyl acrylamide (HEA) and 3-sulfopropyl acrylate potassium salt (SPA). The addition of HEA and SPA is designed to fine-tune the hydrogels’ water absorption and mechanical properties, ultimately enhancing their characteristics and expanding their potential for biomedical applications. A copolymer of AMPS, 2-carboxyethyl acrylate (CEA) combined with methacrylic acid (MAA) as poly(AMPS-stat-CEA-stat-MAA, PACM), was preliminarily synthesized. CEA and MAA were modified with allyl glycidyl ether (AGE) through ring-opening, yielding macromers with pendant allyl groups (PACM-AGE). Copolymers poly(AMPS-stat-HEA-stat-CEA-stat-MAA) (PAHCM) and poly(AMPS-stat-SPA-stat-CEA-stat-MAA) (PASCM) were also synthesized and modified with AGE to produce PAHCM-AGE and PASCM-AGE macromers. These copolymers and macromers were characterized by ¹H NMR, FT-IR, and GPC, confirming successful synthesis and functionalization. The macromers were then photocrosslinked into hydrogels and evaluated for swelling, water content, and mechanical properties. The results revealed that the PASCM-AGE hydrogels exhibited superior swelling ratios and water retention, achieving equilibrium water content (~92%) within 30 min. While the mechanical properties of HEA and SPA containing hydrogels show significant differences compared to PACM-AGE hydrogel (tensile strength 2.5 MPa, elongation 47%), HEA containing PAHCM-AGE has a higher tensile strength (5.8 MPa) but lower elongation (19%). In contrast, SPA in the PASCM-AGE hydrogels led to both higher tensile strength (3.7 MPa) and greater elongation (92%), allowing for a broader range of hydrogel properties. An initial study on drug delivery behavior was conducted using PACM-AGE hydrogels loaded with photosensitizers, showing effective absorption, release, and antibacterial activity under light exposure. These AMPS-based macromers with HEA and SPA modifications demonstrate enhanced properties, making them promising for wound management and drug delivery applications.