Mung Bean Protein-Derived Bioink with Synergistic Antioxidant and Antibacterial Properties for Cartilage Regeneration

The complex microenvironment of articular cartilage defects, characterized by oxidative stress and infection risk, poses a major challenge for regenerative medicine. Here we report a molecular engineering strategy to transform mung bean protein (MBP), an abundant and sustainable plant protein, into a multifunctional, microenvironment-relevant bioink. By sequentially grafting ε-polylysine (EPL) and methacryloyl groups onto the MBP backbone, we created a family of photocurable derivatives (MEM) with tunable methacrylation degrees. Three variants were obtained: MEM-A (65% methacrylation), MEM-B (78% methacrylation), and MEM-C (86% methacrylation). The hydrogels exhibit rapid rheological gelation (<2 s, defined by the G'-G″ crossover), tunable mechanical properties (20-60 kPa compressive modulus), and a porous architecture (100-150 μm pore size, 70-80% porosity) conducive to cell growth. The resulting MEM hydrogels integrate broad-spectrum antimicrobial activity (>90% bacterial killing), enhanced antioxidant capacity (>51% radical scavenging), and excellent DLP printability (>87% printing accuracy). Among these, the MEM-B hydrogel supports chondrocyte viability, upregulates cartilage-specific genes (SOX9, ACAN), and downregulates oxidative stress markers (MMP-3, MMP-13). In a rat osteochondral defect model, MEM-B promoted robust cartilage regeneration with superior ICRS scores and tissue integration compared to GelMA controls. This work establishes a design paradigm for converting underutilized plant proteins into multifunctional bioinks that actively engage with pathological microenvironments, opening sustainable avenues for next-generation regenerative biomaterials.