Aloe vera-enriched collagen-polyurethane hydrogel: Supporting tissue regeneration, antibacterial action and drug release for effective wound healing

Abstract Aloe vera is widely recognized for its healing, anti-inflammatory, moisturizing, and antibacterial properties, which are attributed to its rich biochemical composition, including polysaccharides, proteins, vitamins, and anthraquinones such as aloin and emodin. This study investigates the encapsulation of Aloe vera in collagen-polyurethane hydrogels to create a novel bioactive formulation for wound healing. Hydrogels with Aloe vera content ranging from 20-60 wt.% were prepared, forming scaffolds with a fibrillar-granular morphology and semi-crystalline surface. Encapsulation of Aloe vera resulted in semi-interpenetrating polymer networks (semi-IPNs), with the semi-interpenetration rate increasing as Aloe vera content rose. The formulation containing 60 wt.% Aloe vera significantly enhanced the superabsorbent capacity (2850 ± 210 %) and crosslinking degree (38 ± 3 %) of the matrix while reducing the loss factor (2.5 ± 0.4), resulting in a highly viscous gel ideal for moisture retention and uniform wound coverage. These hydrogels exhibited resistance to biodegradation in the presence of pepsin at skin pH (5.5) and demonstrated notable antibacterial activity, inhibiting E. coli (78 %) and S. aureus (57 %) growth compared to 40 ppm gentamicin. Additionally, they facilitated a gradual release of ketorolac (up to 65 % at pH 5.5 with 20 wt.% Aloe vera). The hydrogels were non-hemolytic and promoted the metabolic activity of monocytes and fibroblasts, enhancing cellular growth. Furthermore, the composition induced no inflammatory response but significantly boosted the secretion of the anti-inflammatory cytokine TGF-β1, potentially enhancing wound healing.