Development of Natural Active Agent-Containing Porous Hydrogel Sheets with High Water Content for Wound Dressings

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

Water-soluble macromers based on 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (Na-AMPS) for rapid in situ hydrogel film formation

The in situ formation of hydrogels has potential for a number of biomedical applications but their generation via conventional polymerization techniques has a number of limitations, such as toxicity and reaction time. The use of macromers in hydrogel formulations can help overcome these limitations. In this work, we synthesized a new functionalized macromer formed via the copolymerization of 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS) and acid-functional monomers that can undergo a ring-opening reaction with allyl glycidyl ether (AGE) to generate the desired pendant vinyl macromer functionality. These macromers were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and gel permeation chromatography (GPC) to provide evidence for successful macromer synthesis and subsequent polymerization. Using a UV-initiated crosslinking approach with poly(ethylene glycol) diacrylate (PEGDA), the hydrogels were fabricated from the macromer solution, with the gelation time being reduced from 1200 s to 10 s when compared to hydrogel formation from regular vinyl monomers. While different acidic monomers result in distinct tensile properties, hydrogels containing 2-carboxyethyl acrylate (CEA) exhibit low strength but high elongation. In contrast, those with methacrylic acid (MAA) demonstrate higher strength and lower elongation. Therefore, using a balanced combination of each is a logical approach for achieving a robust final hydrogel film. In summary, we have produced a new macromer possessing characteristics highly conducive to rapid hydrogel synthesis. This macromer approach holds potential for use in in situ hydrogel formation, where a viscous solution can be applied to the target area and subsequently hardened to its hydrogel. We envisage its application primarily in the biomedical field