Rapid Biofilm Eradication on Bone Implants Using Red Phosphorus and Near‐Infrared Light

TLDR

Bone‑implant infections are frequent after orthopedic surgery, and once a biofilm forms the immune system and antibiotics struggle to eradicate it, making established biofilms difficult to eliminate with current preventive strategies. The study aims to develop a nonsurgical, noninvasive therapy that can eradicate established biofilms on bone implants. Titanium implants were coated with a red‑phosphorus/IR780/arginine‑glycine‑aspartic‑acid‑cysteine layer that provides photothermal heating and singlet‑oxygen generation upon 808‑nm irradiation while promoting cell adhesion and osteogenesis. In vitro and in vivo, 10‑minute 808‑nm irradiation at 50 °C achieved 96.2 % biofilm eradication without damaging surrounding tissue, while the coating enhanced cell adhesion, proliferation, and osteogenic differentiation.

Abstract

Abstract Bone‐implant‐associated infections are common after orthopedic surgery due to impaired host immune response around the implants. In particular, when a biofilm develops, the immune system and antibiotic treatment find it difficult to eradicate, which sometimes requires a second operation to replace the infected implants. Most strategies have been designed to prevent biofilms from forming on the surface of bone implants, but these strategies cannot eliminate the biofilm when it has been established in vivo. To address this issue, a nonsurgical, noninvasive treatment for biofilm infection must be developed. Herein, a red‐phosphorus–IR780–arginine–glycine–aspartic‐acid–cysteine coating on titanium bone implants is prepared. The red phosphorus has great biocompatibility and exhibits efficient photothermal ability. The temperature sensitivity of Staphylococcus aureus biofilm is enhanced in the presence of singlet oxygen ( 1 O 2 ) produced by IR780. Without damaging the normal tissue, the biofilm can be eradicated through a safe near‐infrared (808 nm) photothermal therapy at 50 °C in vitro and in vivo. This approach reaches an antibacterial efficiency of 96.2% in vivo with 10 min of irradiation at 50 °C. Meanwhile, arginine–glycine–aspartic‐acid–cysteine decorated on the surface of the implant can improve the cell adhesion, proliferation, and osteogenic differentiation.