[Content characteristics and cytotoxicity detection of silver ion products]

Objective: To analyze the silver content, homogeneity, and cytotoxicity of silver-containing products. Methods: (1) Five kinds of silver-containing products A, B, C, D, and E were purchased from the market, and products A, B, C, and D are liquid or gel form while product E was dressing form. The silver content of each product and the homogeneity of product E were determined by flame method. The sample number was 3. (2) Human hepatocellular carcinoma cell line (HepG2) was selected as the evaluation model. Four silver-containing products A, B, C, and D were diluted with high-glucose dulbecco's modified eagle medium (DMEM) at multiple ratios of 1∶100, 1∶200, 1∶400, and 1∶800, and then they were used for cell culture. Cells cultured with high-glucose DMEM and high-glucose DMEM containing 20 μg/mL silver nitrate were used as blank control and positive control, respectively. The cell viability was determined by methyl thiazolyl tetrazolium assay, and each sample number was 5. (3) Four mass concentrations of 0.031 3, 0.062 5, 0.125 0, and 0.250 0 μg/mL were prepared from silver-containing product A, and then they were used to culture HepG2 cell. Cells cultured with high-glucose DMEM containing fetal calf serum and 294 μg/mL potassium dichromate were used as positive control, while those containing fetal calf serum were used as blank control. Hoechst 33258 staining method was used to detect apoptosis rate of cells. The tail moment, tail length, and the percentage of DNA in the tail of cells were observed by comet assay to evaluate DNA damage. The sample numbers were all 3. Data were processed with one-way analysis of variance and least significant difference-t test. Results: The silver content of products A, B, C, and D was (256.5±1.5) μg/mL, (271.5±1.3) μg/mL, (652.4±2.6) μg/g , (330.0±2.1) μg/g, which was in accordance with labelled amount. The silver content of product E was (0.158±0.013) mg/g, and the silver content of each piece of product E was (0.125±0.017) mg/g, showing good uniformity of product E. (2) Compared with the rate of blank control, the cell survival rates of product A at the dilution ratio of 1∶100, product B at the dilution ratio of 1∶100, and product C at the dilution ratio of 1∶100 and 1∶200 were significantly reduced (t=35.506, 8.914, 37.594, 30.693, P<0.01). Compared with the rate of positive control, the cell survival rates of product A at the dilution ratio of 1∶200, 1∶400, and 1∶800, product C at the dilution ratio of 1∶400 and 1∶800, products B and D at each dilution ratio were increased significantly (t=27.537, 18.262, 18.709, 26.333, 41.762, 15.776, 19.759, 20.443, 15.715, 26.792, 24.963, 31.803, 30.537, P<0.01). (3) The apoptosis rates of cells treated by 0.250 0 μg/mL product A and positive control were (6.1±0.4)% and (62.2±3.9)% respectively, which were significantly higher than the apoptosis rate of blank control [(3.3±0.7)%, t=13.327, 30.475, P<0.05]. The apoptosis rates of cells treated by 0.031 3, 0.062 5, 0.125 0 μg/mL product A were (2.9±0.4)%, (3.1±0.4)%, and (4.2±0.9)% respectively, which were close to the apoptosis rate of blank control (t=1.181, 0.133, 1.097, P>0.05). (4) The tail moment, tail length, and tail DNA percentage of cells cultured with 0.125 0 and 0.250 0 μg/mL product A were significantly higher than those cultured with blank control (t=29.026, 51.194, 21.851, 36.138, 24.721, 50.455, P<0.05 or P<0.01). However, the tail moment, tail length, and tail DNA percentage of cells cultured with 0.031 3 and 0.062 5 μg/mL product A were close to those cultured with blank control (t=5.878, 3.429, 2.779, 1.960, 1.328, 7.763, P>0.05). Conclusions: The silver content of silver-containing products meets the requirements of the labeling. The concentration of product C is higher than that of other products, leading to a greater possibility of decreasing the survival rate of HepG2 cells. It is suggested that the products A and B should be taken as reference in the concentration setting of silver ion products. The product solution with higher concentration may have higher risk of damage to cell DNA. Therefore, it is not recommended to upregulate silver content of relevant products blindly in order to achieve better antibacterial effect.