Beyond the Modification Degree: Impact of Raw Material on Physicochemical Properties of Gelatin Type A and Type B Methacryloyls

Gelatin methacryloyl (acetyl) (GM(A)) is increasingly investigated for various applications in life sciences and medicine, for example, drug release or tissue engineering. Gelatin type A and type B are utilized for G(A)M(A) and G(B)M(A) preparation, but the impact of gelatin raw material on modification reaction and resulting polymer properties is rather unknown so far. Therefore, the degrees of modification (DMA) and physicochemical properties of five G(A)M(A) and G(B)M(A) derivatives are compared: The degrees of methacryloylation (0.32-0.98 mmol g(-1)) are indistinguishable for G(A)M(A) and G(B)M(A) as are the sol-gel temperatures. Isoelectric points, solution viscosities, and hydrodynamic radii which are distinct for G(A) and G(B,) converge with increasing DMA. Interestingly, differences are measured for the storage moduli and equilibrium degrees of swelling of respective G(A) and G(B) derivative-based hydrogels, in spite of their comparable DMA. This underlines the importance of GM(A) characterization beyond the modification degree.