Immobilization of Ytterbium via Polyphenol Chemistry on Implant Materials for Enhanced Cytocompatibility and...

Bacterial colonization-induced infections and poor cytocompatibility remain critical challenges for diverse biomedical materials, limiting their clinical translation. Herein, we report a versatile surface modification strategy, effective on multiple flat substrates, polydopamine/tannic acid/ytterbium (PDA/TA-Yb) composite coatings on titanium (Ti, metallic), polyurethane (PU, polymer), and polyethylene terephthalate (PET, polymer) substrates via mussel-inspired polyphenol chemistry. The fabrication involves two key steps: (1) formation of a PDA intermediate layer through oxidative self-polymerization of dopamine, enabling robust adhesion to substrates with distinct surface chemistries; (2) immobilization of ytterbium ions (Yb³⁺) via coordination with TA and residual catechol groups of PDA, constructing stable metal-phenolic networks (MPNs) with synergistic covalent and coordination bonds. Comprehensive characterizations (ATR-FTIR, XPS, SEM, AFM, WCA) confirm successful coating deposition with uniform nanoscale granular morphology, enhanced hydrophilicity (water contact angle ∼62°), moderate thickness (110.3-131.2 nm), and excellent long-term stability (only ∼8.1% thickness loss after 7-day PBS immersion). The PDA/TA-Yb coatings exhibit potent antibacterial activity against clinically relevant Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, achieving antibacterial rates of 83.9-93.1% at 24 h and retaining 80.1-88.4% efficacy after 7 days of continuous bacterial challenge. This sustained antibacterial effect arises from synergistic actions of Yb³⁺ (disrupting bacterial membrane integrity) and TA (inhibiting bacterial metabolism). Critically, the coatings maintain excellent cytocompatibility with L929 mouse fibroblasts, with cell viability exceeding 80% even after 7 days of coculture, meeting ISO 10993-5 noncytotoxicity standards. This facile, scalable strategy overcomes the limitations of single-substrate dependence and uncontrolled metal ion release in conventional coatings, offering a versatile platform to engineer multifunctional surfaces for implantable devices, catheters, and medical textiles.