The Evaluation On Biocompatibility Of A New Medical Nickel-free Stainless Steel(BIOSSN4)-In Vitro Cytotoxicity Experiment

ObjectivesIn this experiment, we investigate the cytotoxicity aim of a new medical nickel-free stainless steel (BIOSSN4). L-929 cell line of mice fibroblasts was cultivated with the infusions of BIOSSN4.The proliferation of the cells were investigated using a tetrazolium-based colorimetric assay (MTT assay) and compared with traditional 316L medical stainless steel, Au-alloy, in order to provide a biological basis for the clinical application.Methods1.The experiment materials:The experiment materials were divided into:A set:BIOSSN4 stainless steel, B set:316L stainless steel, C set:Aualloy, D set:Pb. A-D set materials were made into some wafers that diameters were 10mm, the thickness was lmm.After disinfected and sterilized, the materials were put into super clean bench. Then we used the RPMI1640 culture liquids to prepare the extraction liquids of those materials.2.The experiment methods:To take 96 bores culture plates, and add the cell suspending liquids 1 OOul into each bore. Respectively add the A-D set materials extracting liquids 100ul into the Groups 1-4bores, and add RPM11640 culture liquids 100ul into group 5bore, then put them into the culture box. Respectively take out a culture plate after educating 1-3day, and observe the changes of cell form by upside down and discrepancy microscope. To add 5mg/ml MTT liquids 20ul into each bore, and take out the plate after educating 4hours continuously. To suck out the liquids and join DMSO 150ul, into each bore. To examine the optical densisity by automatic enzyme immunoassay analyzer, and calculate the rate of cells relative growth(RGR) and assess the cytotoxic rank of each materials.Results1.The cell's morphological observation:The first day in the positive control the cells growing on the plate showed bursiform or polygon shape, and the supending cells showed circular or irregular form, and appeared vacuoles or grains in the cytoplasm. The cells of the rest groups all almost grew with attaching on the plate, and with enmorphism and the steady cytoplasm. The third day, in the positive control the cells almost shed off, which cytoplasm and cell mucleus concentrated, and even there were many dead cells which plasmalemma collapsed and karyotheca solved. The cells of the rest groups all almost grew with attaching on the plate continuously, and the cells density creased. There were few suspending degenerate cells or dead cells.2. The results of statistical analysis:There were a significant difference in the optical densities between metal material groups or the negative control (P<0.05 or P<0.01). According to the rate of cell's relative growth of the three metal material groups, the sequence form big to small was: the Au alloy, BIOSSN4 stainless steel,316L stainless steel. BIOSSN4 showed slight cytotoxicity,316L stainless steel showed 1-class cytotoxicity. But the statistical analysis result manifested:there were not significant difference in the optical densities between the third metal material groups and the negative control (P>0.05).ConclusionThis experiment results clarifies:BIOSSN4 only have very faint cytotoxicity, which meets the requirement for clinical application. These results provide a biological basis for clinical application...