Smart Coatings Integrating Antimicrobial and Tissue-Remodeling Functions for Implant Interfaces

This study aimed to assess the antimicrobial performance and biocompatibility of our drug delivery platform, based on layer-by-layer (LbL) coating incorporating tetracycline (TC) complexed with anionic β-cyclodextrin (TCβCD) and a pH-responsive poly(methacrylic acid) (PMAA) film, applied to titanium (Ti) surfaces representing abutment components.

A rat subcutaneous implant-related infection model was established using a polymicrobial biofilm derived from peri-implantitis patient saliva. Contaminated Ti controls and coated discs were implanted and analyzed after 1 and 7 days through clinical, microbiological, confocal, and histological assessments. In parallel, in vitro experiments using fibroblast cultures were conducted to evaluate the expression of genes associated with collagen synthesis and extracellular matrix remodeling.

Coated implants exhibited minimal inflammatory response, whereas control specimens presented with purulent exudate. Microbiological analysis demonstrated sustained antimicrobial activity, with > 3 log₁₀ reduction in viable bacteria at both time points. Confocal microscopy confirmed strong microbicidal effects, particularly in the PMAA group. Coatings also modulated host responses, decreasing pro-inflammatory cytokines and increasing anti-inflammatory mediators and matrix remodeling markers. Histology revealed enhanced collagen deposition and accelerated connective tissue maturation, especially with LbL/TCβCD/PMAA, consistent with upregulated collagen-related gene expression observed in vitro.

The multifunctional coating provides sustained antimicrobial activity alongside immunomodulatory and pro-regenerative effects, supporting its potential to treat implant-related infections while enhancing peri-implant soft tissue remodeling.