Gelatine-based foams produced by enzymatic foaming: formulation–structure relationships affecting expansion and stability

Abstract

Gelatine-based foams are attractive wound-dressing materials due to their biocompatibility, conformability, and exudate-absorptive capacity; however, most reported systems rely on mechanical or chemical foaming routes that offer limited control over expansion and structural stability under physiological conditions. Here, a biodegradable gelatine-based solidified foam is developed via catalase-mediated enzymatic oxygen generation followed by glutaraldehyde-induced network stabilisation, enabling rapid in situ foam formation and fixation at 37 °C. A systematic parametric study was conducted to elucidate the effect of gelatine, hydrogen peroxide, catalase, and glutaraldehyde concentrations on foam expansion and 24 h volume retention. Statistical analysis (one-way ANOVA with Tukey's post hoc test) showed that foam behaviour reflects the interplay among enzymatic gas generation, interfacial stabilisation by gelatine, and matrix stiffening through covalent cross-linking. Excessive gas generation or cross-link density reduced structural integrity, whereas intermediate formulation ranges produced foams with improved expansion–stability balance. A practical formulation window was identified (2.0–3.0 wt% gelatine, 3.0–4.0 wt% hydrogen peroxide, 0.2 wt% catalase, and 2.5–3.0 wt% glutaraldehyde), providing a favourable compromise between high expansion and sustained volume retention over 24 h. These results provide formulation-level design guidance for enzymatically generated biomedical foams and support their potential as flexible, absorbent wound-dressing materials.