Synergistic Calcium Phosphate–Polyphenol Reinforcement Enables Tough, Antibacterial, and Biocompatible PLA-Based Hydrogels

Although extremely attractive for biomedicine, degradable hydrogels often suffer from poor mechanical properties and bacterial contamination. Herein, ultrafine calcium phosphate oligomers (CPOs, 9 wt.‰) and tannic acid (TA) were integrated into a poly(acrylamide-co-lactic acid) (PAMLA) hydrogel to construct a composite hydrogel PAMLA-CPO9/TA with a dynamic multinetwork architecture. In this sustainable and synergistic reinforcement strategy, CPOs serve as inorganic cross-linking nodes that enhance mechanical robustness and resistance to deformation, while TA introduces reversible hydrogen and coordination bonding, providing additional structural stabilization and bacterial antiadhesion properties. The resulting PAMLA-CPO9/TA hydrogel exhibited a tensile strength of 0.19 MPa at 398% elongation and a compressive strength of 2.81 MPa at 80% strain, representing a 4-fold enhancement in the mechanical response over pristine PAMLA. The relative bacterial adhesion of Escherichia coli on the PAMLA-CPO9/TA hydrogel was reduced by over 99% compared to PAMLA, demonstrating excellent biocompatibility by maintaining >92% HeLa cell viability. The synergistic inorganic–organic, calcium phosphate–polyphenol interactions enabled significantly improved mechanical properties and excellent bacterial-repelling and biocompatibility of the PAMLA-CPO9/TA hydrogel, holding a great potential for designing sustainable, multifunctional, and degradable materials for wound-dressing applications.