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

Abstract

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.

Keywords: hydrodynamic radius; isoelectric point; methacryloylated and acetylated gelatin; storage modulus; viscosity.