TABLE 2.

Controlled release of antimicrobial agents on the PEEK-PDA (2 mg/ml dopamine hydrochloride) surface.

Ion	Sample	Method	Bacterial strain	Antibacterial test	Antibacterial property	Mechanism	Biological effect	Reference
AgNPs	Tollens’ reagent (0.02 mol/L) [ammonia into AgNO3 solution (0.02 mol/L)]	PEEK-PDA immersed in the Tollens’ reagent for 30 min	E. coli , S. aureus, and S. aureus	Plate counting and SEM IAI model in rat femur	97.9 ± 0.8% 99.8 ± 0.1% (antibacterial rate) S. aureus growth was significantly inhibited on the surface	Fast Ag+ release initially, then slow release for long-term	Showed low toxicity to MC3T3-E1 cell and possessed good biocompatibility and osseointegration	Gao et al. (2017)
AgNPs、SF/GS	AgNO3–gentamicin (500 lg/mL in PBS) and silk fibroin	SP–PDA–Ag immersed into gentamicin followed by three silk layers	E. coli and S. aureus	Plate counting and SEM	Greatly enhanced the antibacterial effects and antiadhesion ability	The release rate of Ag+ and GS increased with decreasing pH	PDA and silk fibroin can balance cytocompatibility and antibacterial ability	Yan et al. (2018)
KR-12	KR-12 solution (1 mg/ml in 10 mM Tris–HCl buffer)	PEEK-PDA immersed in KR-12 solution under reverse nitrogen (N2) flow overnight	S. aureus and S. aureus	Plate counting and SEM IAI model in rat femur	Effectively inhibited bacteria proliferation and biofilm formation in vitro and in vivo	Release of KR-12 which has a broad spectrum of antibacterial activity	rBMSCs: improved adhesion, proliferation, and osteogenic differentiation; in vivo: promoted osteointegration in rat femur	Meng et al. (2020)
GS	PDA and GS diluted in Tris–HCl solution (2 mg/ml and 3 mg/ml)	SPEEK was immersed in the left solution for 12 h	E. coli , S. aureus, and S. aureus	Plate counting IAI model in rat femur	Continuous antibacterial abilities. Imaging showed no evidence of osteomyelitis	GS release	Possessed good biocompatibility and the immunoregulatory ability	Sun et al. (2021)
Mino liposomes	Minocycline (Mino), liposome, and dexamethasone (DEX)	PEEK-PDA immersed in the Dex/Mino liposome solution obtained by the thin-film hydration method	S. mutans, P. gingivalis, and S. mutans	Plate counting and microbial viability assay kit-WST subcutaneous infection model of rats	Improved the antibacterial activity and inhibited the initial adhesion. The antibacterial efficiency was about 97.4%	Liposomal Mino releasing and benign cell adhesion on the functionalized PEEK surface	In vitro, improved osteogenic differentiation of human mesenchymal stem cells. In vivo, enhanced osteointegration	Xiao Xu et al. (2019)
Zn2+–Mg2+	Mg(NO3)2·6H2O、Zn(NO3)2·6H2O、2,5-dihydroxy-terephthalic acid (DHTA) dexamethasone (DEX)	PEEK-PDA was dipped in Zn−Mg-MOF74 composite obtained by hydrothermal synthesis and then coated by DEX	E. coli, S. aureus, and S. aureus	Plate counting and SEM fluorescence microscope subcutaneous infection model of rats	Significantly inhibited bacterial proliferation. Much smaller number of bacteria	Mg2+, Zn2+, and DHTA release. The alkaline microenvironment due to the coating degradation	Improved vascularization and osteogenic differentiation	Xiao et al. (2021)
Van-GNPs	vancomycin (Van)–Gelatin nanoparticles (GNPs)	Plasma modification (PDA/P-PEEK) combines two-step desolvation (Van-GNPs)	S. aureus and S. mutans	Plate counting and SEM	Inhibited bacteria adhesion and the cell membrane bursted on the Van-GNPs/PEEK surface	Vancomycin release	Good osteogenesis without cytotoxicity	Tianjie Chen et al. (2021)
AgNPs–µCuO/SF	Cu(NO3)2 •3H2O、AgNO3, Silk fibroin SPEEK	μCuO was prepared by hydrothermal solution followed by polymerization	E. coli and S. aureus	Plate counting and SEM	Effectively inhibited bacteria adhesion and biofilm formation	Cu2+ and Ag+ release	Showed better osteogenesis in the rabbit tibial defect model	Yan et al. (2020)