| Recently,Titanium implants are widely used clinically due to the high strength,durability and biocompatibility of titanium.However,biomaterial-associated infection remains a serious problem for titanium implants,especially in dental and orthopaedic applications.Despite strict operative procedures such as thorough disinfection,prophylactic antibiotics and stringent aseptic surgical protocols,post-operation infection usually occurs and complications can also be caused by bacterial invasion from nearby tissues or a hematogenous source at a later time.Microbial contamination on material surfaces is a major challenge in biomaterial applications.Therefore,the improvement of the antibacterial ability is effective to increase the service life of biomaterials.It is of great importance to fabricate the titanium materials with good biocompatibility and excellent antibacterial activities as titanium implants.In this thesis,the titanium was modified by the combination of biomolecules and silver and the biomolecule/silver layer was prepared on the titanium surface.The physicochemical properties of the resultant biomolecule-silver-titanium composite materials were investigated by fourier transformed infrared spectroscopic(FTIR),contact angle(CA),field-emission scanning electron microscopy(FE-SEM)and inductively-coupled plasma atomic emission spectrometry(ICP-OES)analysis.The antibacterial ability of the biomolecule-silver-titanium composite materials was investigated by studing their antibacterial effect against planktonic bacteria in the suspension and adhesive bacteria.The biocompatibility of the biomolecule-silver-titanium composite materials was investigated by studing the growth of osteoblast cells on the sample surface,alkaline phosphatase(ALP)activity as well as lactate dehydrogenase activity(LDH)assay.The results obtained are described as follows:(1)The titanium was modified by the combination of human serum albumin(HSA)and silver.The HSA/silver layer was fabricated on titanium,and the Ti-HSA-Ag specimens were obtained.The formation of silver nanoparticles on the titanium surface was investigated in the presence of HSA.The antibacterial activities,cytotoxicity and biocompatibility of the specimens were systematically investigated.Ti-HSA-Ag specimens show excellent antibacterial ability against planktonic bacteria in the suspension and ability to prevent bacterial adhesion,and the antibacterial rate of Ti-HSA-Ag3 is as high as 100%.Ti-HSA-Ag specimens are nontoxic compared with the titanium without HSA/silver treatment.Osteoblast cells can grow and proliferate on Ti-HSA-Ag specimens.ALP activity results show that osteoblast cells can differentiate and synthsize ALP enzyme.(2)A small biomolecule,glutathione(GSH),was chosen as the matrix.The titanium was modified by the combination of GSH and silver,and the Ti-GSH-Ag was obtained.The formation of silver nanoparticles was studied.The antibacterial activities,cytotoxicity and biocompatibility were systematically investigated.The Ti-GSH-Ag specimens show excellent antibacterial ability against planktonic bacteria in the suspension and ability to prevent bacterial adhesion,and the antibacterial rate is related to the silver content of the specimen.With increasing incubation time,the ALP activities of the Ti-GSH-Ag increase.Ti-GSH-Agl and Ti-GSH-Ag2 are nontoxic to the osteoblast cell,while support the growth and differentiation of osteoblast cell.(3)The hemoglobin(Hb)was chosen to prepare Hb/silver nanoparticles layer,and the Ti-Hb-Ag was obtained.The physicochemical properties of the Ti-Hb-Ag specimens were studied.Furthermore,the antibacterial activities of the specimens were investigated against planktonic bacteria and adhesive bacteria,and the antibacterial ability,cytotoxicity as well as biocompatibility are compared before and after silver incorporation.The specimen without silver shows no antibacterial effect against planktonic bacteria and adhesive bacteria,while the specimens with silver show significantly enhanced antibacterial ability.The ALP activity and cell proliferation of the silver-doped specimens are similar to those of titanium,and the Ti-Hb-Ag specimens are notoxic.(4)The titanium with nanotopography was fabricated by anodization.HSA and Hb were chosen as the matrix for the adsorption and reduction of silver ions,and the nano-Ti-Hb-Ag and nano-Ti-HSA-Ag were obtained.The formation of HSA-Ag and Hb-Ag nanoparticles were studied.The antibacterial ability,cytotoxicity and biocompatibility were systematically investigated.The nano-Ti-Hb-Ag and nano-Ti-HSA-Ag specimens show excellent antibacterial activities,with the specimen containing higher silver amount exhibits stronger antibacterial effect.The silver-doped specimens show no obvious toxicity,and support the growth and differentiation of osteoblast.On the titanium with nanotopography,the osteoblast cells show stronger proliferation ability.(5)The titanium nanotube was fabricated on the titanium surface by anodization.The NT-Ti-Hb-Ag and NT-Ti-HSA-Ag specimens were obtained.The physicochemical properties of these specimens were studied.The antibacterial ability,cytotoxicity and biocompatibility of the specimens were systematically investigated.The antibacterial rates of NT-Ti-Hb-Ag3 and NT-Ti-HSA-Ag3 are as high as 100%against planktonic bacteria and adhesive bacteria.The specimens with titanium nanotube morphology show better proliferation ability of osteoblast cell than pure titanium,and exhibit no obvious cytotoxicity to osteoblast cell.(6)The properties of the specimens with different biomolecules and titanium substrates are compared.The results show that the specimens obtained by using different biomolecules or titanium substrates possess different CA and free energy values.The growth of osteoblast cell is also different on these specimens.The order of osteoblast cell amounts is consistent with the order of hydrophilic property and free energy of the specimens.The specimens with hemoglobin matrix or titanium nanotube substrate possess the highest hydrophilic property and free energy,on which the osteoblast cell shows the strongest growth ability. |
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