Size-dependent in vitro cytotoxicity assay of gold nanoparticles

Gold nanoparticles (AuNps) may serve as a promising model to address the size-dependent biological response of cell lines. Their size can be controlled with great precision during chemical synthesis. AuNps have potential applications in drug delivery, cancer diagnosis, and therapy, in the food industry, and for environmental remediation. However, some of the recent literature contains conflicting data regarding the cytotoxicity of gold nanoparticles. Against this background, a systematic study of water soluble gold nanoparticles stabilized by citrate ranging in size from 3?nm to 45?nm were synthesized. The cytotoxicity of these particles were tested by employing the (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide reduction assay), the neutral red cellular uptake assay, and lactate dehydrogenase release assay. Noticeable differences in the cytotoxic effects depending on the assay, and the nanoparticle size have been found. Citrate stabilized gold nanoparticles with sizes of 3?nm, 8?nm, and 30?nm were more sensitive to the cell lines and caused gradual cell death within 24?h at higher concentrations. This results in IC50 values ranging from 57 to 78?μgmL^?1 depending on the particle size, and cell line combinations. In contrast, AuNps with diameters of 5?nm, 6?nm, 10?nm, 17?nm, and 45?nm were nontoxic up to three to four fold higher concentrations, and at long-term exposure.     

The Cytotoxicity of Some Organic Solvents on Isolated Hepatocytes in Monolayer Culture

The cytotoxic effects of volatile and water-insoluble organic solvents (ethylbenzene, tetrachloroethylene, n-hexane) were tested on isolated hepatocytes in monolayer culture by using the 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reduction assay. All of the tested compounds inhibited metabolic activity of hepatocytes and this effect depended on the concentration of solvents in the incubatory medium. The presence of fetal calf serum in the medium did not change the cytotoxicity of xenobiotics. IC₅₀ values calculated on the basis of the MTT assay indicated that ethylbenzene was more cytotoxic than tetrachloroethylene and n-hexane. Using hepatocyte monolayer culture and the MTT assay to assess cytotoxicity of organic solvents causes many technical problems. It seems that it cannot be used as a rapid, cheap, and credible method.     

甲醛诱导Hela细胞凋亡的研究

细胞凋亡是当今环境毒理学领域的研究热点之一.为了探讨甲醛能否诱导细胞凋亡,以Hela细胞为实验材料,通过不同浓度的甲醛处理24h后,应用形态学观察、四甲基偶氮唑蓝(MTT)实验和流式细胞仪检测了Hela细胞凋亡情况.实验结果表明低浓度甲醛(≤0.2mmol·L-1)处理Hela细胞24h后,对细胞生长有显著的抑制作用(p<0.05),但对细胞形态改变不大,且对细胞核DNA没有损伤;而高浓度甲醛(≥0.4mmol·L-1)处理Hela细胞24h后,对细胞生长有极显著的抑制作用(p<0.01),细胞形态逐渐变的模糊不清,并有少量细胞萎缩成圆形,且会造成细胞核DNA有规律的断裂,细胞凋亡率随甲醛浓度的增加而增大.以上实验结果显示,高浓度甲醛处理Hela细胞24h后,会诱导细胞凋亡;并且随甲醛浓度的升高凋亡率逐渐增大,呈一定的剂量-效应关系.