Modulating physicochemical properties of collagen films by cross-linking with glutaraldehyde at varied pH values

Collagen films cross-linked with glutaraldehyde (GTA) at different pH values were prepared to explore the influence of pH on their physicochemical properties. The films were characterized using FTIR spectroscopy, XRD analysis, SDS-PAGE, shrinkage temperature, fluorescence analysis and SEM. The results indicated that cross-linking degree and reaction position were different at different pH values. The optimal cross-linking degree in collagen films was obtained under neutral and alkaline conditions. The main reaction under acidic conditions was intramolecular cross-linking and this gradually shifted to intermolecular cross-linking with an increase in pH. Cross-linked films had improved mechanical properties and thermal stability as well as higher b* values compared to films without cross-linking. These improvements correlated with the degree and position of cross-linking reactions. Controlling the reaction pH can be used to modulate the physicochemical properties of the collagen films to match specific application requirements.