Disclosed herein are gelatin particles including gelatin, wherein when a major-axis length of dried gelatin particles is defined as a and a major-axis length of gelatin particles after swelling treatment obtained by immersing the dried gelatin particles in water at 40 C. under an atmospheric pressure for 60 minutes is defined as b, swelling degree represented by b/a is 1.0 or more but 10.0 or less, and wherein the gelatin particles after swelling treatment have a particle diameter of 1.0 nm or more but 5.0 m or less. The gelatin particles are easily taken up by cells themselves.

An elastomeric nanocomposite hydrogel includes first natural polymer macromers covalently crosslinked with second natural polymer macromer and physically crosslinked with a plurality of inorganic nanoparticles. The elastomeric nanocomposite hydrogel is cytocompatible, and, upon degradation, produce substantially non-toxic products.