# Antibiotic-free antimicrobial functionalization of PEEK via UV-induced self-initiation and N-halamine grafting

## TL;DR

This study develops a durable, antibiotic-free antibacterial surface for PEEK implants using N-halamine grafting, effectively preventing infections while maintaining biocompatibility.

## Contribution

A UV-induced self-initiation and N-halamine grafting method is introduced to create antibiotic-free antibacterial PEEK surfaces with translational potential.

## Key findings

- PEEK-g-PAM-NCl showed >98% bacterial reduction in vitro against both Gram-positive and Gram-negative bacteria.
- In vivo tests showed reduced bacterial burden and tissue damage without systemic or local toxicity.
- The modification preserved osteogenic differentiation and biocompatibility in vitro.

## Abstract

Implant-associated infection remains a major challenge in orthopedic surgery. Although polyether ether ketone (PEEK) is widely used owing to its favorable mechanical properties and radiolucency, its intrinsic bioinertness renders it highly susceptible to bacterial colonization. Developing a durable, antibiotic-free antibacterial surface modification for PEEK with translational relevance remains clinically desirable.

In this study, a covalently grafted N-halamine–functionalized PEEK surface (PEEK-g-PAM-NCl) was fabricated via a UV-induced self-initiated polymerization strategy. The antibacterial performance was systematically evaluated against Staphylococcus aureus and Escherichia coli using time–kill assays, live/dead staining, and antibacterial tests under protein-rich conditions. Biocompatibility and osteogenic potential were assessed in vitro using hBM-MSCs. In vivo antibacterial efficacy and biocompatibility were further investigated using subcutaneous implant-associated infection model in the C57BL/6J mice and femoral osteomyelitis model in the SD rat.

PEEK-g-PAM-NCl exhibited sustained and effective antibacterial activity against both Gram-positive and Gram-negative bacteria, achieving >98% bacterial reduction in vitro, including under protein-rich conditions. Time–kill assays revealed a pronounced time-dependent bactericidal effect. In vivo, PEEK-g-PAM-NCl significantly reduced bacterial burden, inflammatory infiltration, and infection-associated tissue damage compared with pristine PEEK, effectively preventing chronic osteomyelitis features. Importantly, no abnormal systemic inflammatory response or local tissue toxicity was observed. In vitro osteogenic assessments demonstrated that the antibacterial modification did not adversely affect osteogenic differentiation.

This study demonstrates that covalent N-halamine functionalization endows PEEK with sustained, antibiotic-free antibacterial activity while preserving biocompatibility performance. PEEK-g-PAM-NCl represents a promising translational strategy for preventing implant-associated infections in orthopedic applications.

This study presents an antibiotic-free antibacterial surface modification strategy for PEEK implants based on UV-induced covalent grafting of N-halamine polymers. The robust antibacterial efficacy, preserved cytocompatibility, and supportive bone-related biological responses suggest potential applicability in preventing implant-associated infections in orthopedic settings. This work provides a feasible surface engineering approach that may be further optimized and translated toward clinically relevant load-bearing implants.

A photo-induced self-initiation and chlorination approach enables the functionalization of PEEK with N-halamine groups (PEEK-g-PAM-NCl), imparting robust antibacterial activity while preserving biocompatibility. This antibiotic-free surface modification offers a promising strategy for reducing implant-associated infections in orthopedic applications.Image 1