Abstract: BACKGROUND: The complications caused by bacterial infection seriously affect the long-term efficacy of implants, so the antibacterial performance is of great significance in the design of implant surface. 
OBJECTIVE: To construct chlorhexidine-loaded phenolic amine cross-linked coating on the surface of porous titanium, and to evaluate the antibacterial properties and osteoblast compatibility of the coating.
METHODS: The titanium sheet was polished, cleaned, dried, and soaked in NaOH solution, placed in a 60℃ drying box for 24 hours, washed and dried in boiling water, and then recorded as the control group. The titanium sheet of the control group was immersed in the Tris solution containing epigallocatechin gallate and hexanediamine for 24 hours, washed and dried, and recorded as the phenolamine group. The titanium sheet of the phenolamine group was soaked in the chlorhexidine solution for 24 hours, washed and dried, and recorded as the chlorhexidine group. The samples were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, water contact angle meter, and NH group quantification. The antibacterial ability of each group was evaluated by live/dead bacteria staining, bacteriostatic ring method, and turbidity method. The biocompatibility of each group was evaluated by methyl thiazolyl tetrazolium method and fluorescent staining. The cell adhesion ability of each group in the bacterial environment was evaluated by bacterial-cell coculture. 
RESULTS AND CONCLUSION: (1) The surface of titanium sheet in the chlorhexidine group was covered by a large number of spherical particles, and the Cl2p peak appeared. The water contact angle rose to (24.6±3.3)°, and the NH content was (46.14±7.63) nmol/cm2, which proved that the coating was successfully constructed. (2) The antibacterial results showed that the bacterial adhesion on the surface of chlorhexidine group was the lowest and all of them were dead bacteria. There was a transparent bacteriostatic ring around the coating, and the bacteria did not proliferate in the culture system. It is proved that the coating can inhibit bacteria on and around the material. There were more bacteria on the surface of titanium sheets in the control group and the phenolamine group, and live bacteria were more common. There was no obvious antibacterial ring around, and the bacterial proliferation in the culture system was obvious. (3) Cell results showed that the titanium sheet in the chlorhexidine group slightly inhibited cell adhesion but did not affect cell proliferation. (4) Bacterial-cell coculture results showed that only chlorhexidine group adhered to a large number of cells, and the cell morphology was good. (5) The results confirmed that chlorhexidine grafted surface was successfully constructed and had good antibacterial ability, which was beneficial to the adhesion and proliferation of osteoblasts in the bacterial environment. 

Key words: implants, titanium sheet, surface modification, epigallocatechin gallate, chlorhexidine, antibacterial