A Photoinitiator‐Free Bioink Platform: Tyrosine‐Assisted UV Crosslinking of Decellularized Extracellular Matrix/Zein Scaffolds Optimized by Full Factorial Design

ABSTRACT The clinical translation of 3D‐bioprinted tissues is significantly limited by the cytotoxicity of synthetic photoinitiators used in photopolymerizable bioinks. To address this critical challenge, we developed a novel, fully photoinitiator‐free bioink platform based on methacrylated decellularized extracellular matrix (dECM‐MA) and a biomacromolecular crosslinker zein (BMC‐Z). The key innovation of this work is the exploitation of the innate UV reactivity of tyrosine residues naturally abundant in dECM, which function as an intrinsic photoinitiator system. BMC‐Z plays a dual role, simultaneously providing immediate rheological stability through a hydrophobic physical network and enhancing the tyrosine‐mediated radical generation for covalent photocrosslinking. A Full Factorial Design (FFD) was employed to efficiently optimize the complex interactions between dECM‐MA, hyaluronic acid (HA), hydroxyapatite (HAp), and BMC‐Z. The optimal formulation (40 mg/mL dECM‐MA, 2 mg/mL HA, 3 mg/mL HAp, 160 μL BMC‐Z) exhibited excellent viscoelastic properties (tan δ = 0.286) and significantly enhanced storage modulus (G′). Remarkably, this bioink supported outstanding biological performance, demonstrating 95% ± 3% cell viability over 14 days and a 4.8‐fold increase in cell proliferation (4.16 × 10 5 → 2.0 × 10 6 cells/scaffold). This study introduces a paradigm‐shifting, non‐toxic, and high‐performance bioink strategy that effectively eliminates the dependency on exogenous photoinitiators, paving the way for safer and more clinically relevant tissue engineering applications.