Study On Synthesis And Biological Properties Of SiC Nanowires With Three-dimensional Structure

Dental composite material with high strength, high toughness and excellentbiological properties has become the focus of the researches on dental restorativematerials. Because of the stable physical and chemical properties, excellent optical,electrical and mechanical properties and the corresponding biological characteristics,Si C nanowire has become the first choice of material for the clinical application ofbiomaterials. This paper employs novel synthetic methods to prepare Si C nanowireswith different lengths, conducts analysis and characterization of the microstructuresand studies the compatibility of the Si C nanowires with cells and safety testing of theanimal experiment of Si C nanowires with three-dimensional structure.According to this paper, the atmosphere pressure heat treatment process isemployed to synthesize the Si C nanowire at low temperature by usingmonocrystalline silicon pieces and graphite as raw materials, wherein the nanowirehas a monocrystalline face centered cubic structure, shows a curved shape, and growsin accordance with the bottom-to-top VLS mechanism; and then boric acid, silica soland sucrose are used as raw materials for the synthesis of an amorphous Si O2/C nanocomposite powder containing boron, and a large amount of Si C nanowires areobtained by atmosphere heat treatment process, wherein the nanowire has uniformsize, monocrystalline face centered cubic structure and high purity. And the growthmechanisms of the Si C nanowires prepared by the two different processes areanalyzed respectively.The in vitro biocompatibility study is carried out by employing nano-sized andmicron-sized Si C nanowires. MTT results show that the micron-sized Si C nanowirehas good in vitro biocompatibility and that the nano-sized nanowire as comparedwith the control group has obvious inhibitory effect on cell growth along with theincrease of the concentration of the nanowire, and the cell survival rate decreasessignificantly. According to the research on Western Blot detection of apoptosis-related protein factors, the micron-sized Si C nanowire as compared with the controlgroup has no significant difference; and after 24 h of action on MC3T3-E1 cells bythe nano-sized nanowire, the expression of Bax and cleaved-Caspase proteins 3 in thecells is on the increase with the increase of the action concentration of the nanowire,and the expression of the Bcl-2 protein decreases with the increase of the actionconcentration of the nanowire, and differences occur both in comparison with thecontrol group, which indicates statistical significance. The results of oxidative stressreaction show that the nano-sized Si C can induce oxidative stress on the cells, whichcauses peroxidation damage of membrane lipid on the cell and tissue levels, inducingcell apoptosis. Intracellular ATP test has further proved that the apoptosis of cells bythe nano-sized Si C nanowire is carried out mainly through the mitochondrialpathway; and as for the micron-sized Si C nanowire, the cells have morphologybasically the same as that of normal cells and grow in fusiform shape and withadherence, and detection results of cell survival rate, apoptosis related protein factorand oxidative stress reaction have no obvious difference with that of a normal cellexperimental group, thereby showing good biocompatibility in vitro.Animal experiments, including oral mucous membrane irritation test, acutesystemic toxicity test and hemolysis studies, use three-dimensional net-like structurecomposed of the micron-sized Si C nanowire.The results of oral mucous membraneirritation test show that all rabbits are alive and in normal activity and diet within 2weeks after the operation. Mucosa shows no epithelial hyperkeratosis orhyperkeratosis phenomena, the whole cell of mucosa tissue are in layeredarrangement with clear uniform order, and the basal membrane structure is integraland continuous.The acute systemic toxicity test is carried out on mature mice. Afterinjection of Si C nanowires with three-dimensional net-like structure extract, noabnormal reaction or symptom of acute poisoning is observed, no death case occurs,and neither structure changes of internal organs of the mice nor changes of a pluralityof enzyme systems and defense function of the body are induced; and originalcomponents of the blood are not destroyed.Results of osteogenesis experiment inmice with bone defect show that the Si C nanowires with three-dimensional structureextract has no acute systemic toxicity, and the Si C nanometer fiber materialcomposite membrane has plays a certain role in inducing new bones, and canaccelerate the growth of bone tissues and promote healing of defects; and wespeculate the correlative factors causing the phenomenon.In vivo biologicalexperiments show that the Si C nano material has good biocompatibility, and meetsthe clinical application requirements for biomedical materials.