BACKGROUND:Pure titanium and titanium alloy implants are widely used in the field of implant restoration due to their excellent biocompatibility and elastic modulus.However,the biological inertness of the surface of titanium-based implants leads to poor integration with surrounding bone tissues,and surface modification is required to improve the bone integration ability of titanium-based implants.OBJECTIVE:To fabricate hydroxyapatite/graphene oxide/interleukin-4 composite coatings on pure titanium substrates,and to investigate their physicochemical properties and biocompatibility of the coating materials.METHODS:Hydroxyapatite/graphene oxide/interleukin-4 composite coatings were prepared on pure titanium substrates by electrochemical deposition and freeze-drying.Titanium sheets loaded with interleukin-4 and titanium sheets loaded with hydroxyapatite/graphene oxide coatings were prepared at the same time,and the physicochemical properties of pure titanium sheets and the above three titanium sheets were characterized.MC3T3-E1 cells were inoculated on the surfaces of pure titanium sheets and the above three titanium sheets,respectively.Cell proliferation was detected by CCK-8 assay and DAPI staining.Cell activity was detected by Calcein-AM/PI staining.Cell morphology and adhesion were observed by scanning electron microscopy.RESULTS AND CONCLUSION:(1)Scanning electron microscopy,energy-dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,X-ray diffraction,and Raman spectroscopy confirmed the successful fabrication of the hydroxyapatite/graphene oxide/interleukin-4 composite coating on the titanium surface.The water contact angle of hydroxyapatite/graphene oxide/interleukin-4 group was larger than that of pure titanium group and hydroxyapatite/graphene oxide group,and smaller than that of interleukin-4 group.(2)CCK-8 assay and DAPI staining results showed that hydroxyapatite/graphene oxide/interleukin-4 coating could promote the proliferation of MC3T3-E1 cells.Calcein-AM/PI staining results showed that MC3T3-E1 cells in hydroxyapatite/graphene oxide/interleukin-4 coating group had higher activity and fewer dead cells.Scanning electron microscopy showed that MC3T3-E1 cells adhered to the surfaces of the four groups of materials with good cell morphology.Compared with the pure titanium group,the MC3T3-E1 cells in the interleukin-4 group extended more pseudopodia,the cell-cell connections were closer,and the adhesion area was larger;compared with the hydroxyapatite/graphene oxide group,the MC3T3-E1 cells in the hydroxyapatite/graphene oxide/interleukin-4 group extended more pseudopodia,the cell-cell connections were closer,and the adhesion area was larger.(3)These findings indicate that the hydroxyapatite/graphene oxide/interleukin-4 composite coating possesses favorable physicochemical and biological properties.

BACKGROUND:Pure titanium and titanium alloy implants are widely used in the field of implant restoration due to their excellent biocompatibility and elastic modulus.However,the biological inertness of the surface of titanium-based implants leads to poor integration with surrounding bone tissues,and surface modification is required to improve the bone integration ability of titanium-based implants.OBJECTIVE:To fabricate hydroxyapatite/graphene oxide/interleukin-4 composite coatings on pure titanium substrates,and to investigate their physicochemical properties and biocompatibility of the coating materials.METHODS:Hydroxyapatite/graphene oxide/interleukin-4 composite coatings were prepared on pure titanium substrates by electrochemical deposition and freeze-drying.Titanium sheets loaded with interleukin-4 and titanium sheets loaded with hydroxyapatite/graphene oxide coatings were prepared at the same time,and the physicochemical properties of pure titanium sheets and the above three titanium sheets were characterized.MC3T3-E1 cells were inoculated on the surfaces of pure titanium sheets and the above three titanium sheets,respectively.Cell proliferation was detected by CCK-8 assay and DAPI staining.Cell activity was detected by Calcein-AM/PI staining.Cell morphology and adhesion were observed by scanning electron microscopy.RESULTS AND CONCLUSION:(1)Scanning electron microscopy,energy-dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,X-ray diffraction,and Raman spectroscopy confirmed the successful fabrication of the hydroxyapatite/graphene oxide/interleukin-4 composite coating on the titanium surface.The water contact angle of hydroxyapatite/graphene oxide/interleukin-4 group was larger than that of pure titanium group and hydroxyapatite/graphene oxide group,and smaller than that of interleukin-4 group.(2)CCK-8 assay and DAPI staining results showed that hydroxyapatite/graphene oxide/interleukin-4 coating could promote the proliferation of MC3T3-E1 cells.Calcein-AM/PI staining results showed that MC3T3-E1 cells in hydroxyapatite/graphene oxide/interleukin-4 coating group had higher activity and fewer dead cells.Scanning electron microscopy showed that MC3T3-E1 cells adhered to the surfaces of the four groups of materials with good cell morphology.Compared with the pure titanium group,the MC3T3-E1 cells in the interleukin-4 group extended more pseudopodia,the cell-cell connections were closer,and the adhesion area was larger;compared with the hydroxyapatite/graphene oxide group,the MC3T3-E1 cells in the hydroxyapatite/graphene oxide/interleukin-4 group extended more pseudopodia,the cell-cell connections were closer,and the adhesion area was larger.(3)These findings indicate that the hydroxyapatite/graphene oxide/interleukin-4 composite coating possesses favorable physicochemical and biological properties.