▎ 摘　　要

NOVELTY - Bio-ink composition comprises graphene oxide complex gelatin-based hydrogel; horseradish peroxidase; hydroxyperoxide; glucose oxidase; and glucose. USE - The composition is useful for three-dimensional printing (claimed). ADVANTAGE - The composition has pre-gelled state when producing three-dimensional structure; excellent three-dimensional printability and cell viability; and promotes cell differentiation even when printing living tissues i.e. artificial organs. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) producing structure by using the bio-ink composition; and (2) producing structure comprising (a) preparing a bio-ink composition for 3D printing by mixing the first agent and the second agent, and (b) preparing structure using the bio-ink composition.