关键词: 纳米材料, 碲化镉量子点, 纳米金, 碳纳米点, 毒性, 非均一性, 环境敏感性, 生物分析

By taking the three commonly used CdTe quantum dots (CdTe QDs), Au nanoparticles (Au NPs) and carbon nanodots (C-dots) as example, we have demonstrated and summarized some noteworthy problems of nanomaterials in bioanalytical applications. These problems mainly include the toxicity, microscopic heterogeneity and environmental susceptivity of nanomaterials, which had been separately discussed with different depths but unfortunately are often overlooked in practice. In the present work, a parallel comparative investigation was first made on cytotoxicity, which reveals that CdTe QDs can lead to the decrease of cell metabolic activity, cell shrinkage, and even cell death; Au NPs at a higher concentration (30 μg/mL) decrease the metabolic activity of cells to a small extent; C-dots exert no obvious toxicity to live cells, showing good biocompatibility. These studies indicate that the relative toxicity of the three nanomaterials in their bare forms is CdTe QDs>>AuNPs>C-dots, which is further supported by the inhibition experiment on the growth of green gram sprouts. Second, the microscopic heterogeneity of nanomaterials was compared with that of resorufin (a small molecular fluorescent dye) by cell imaging experiments, which clearly shows that the distribution of nanomaterials in cells is much less uniform than that of small molecular probes. Besides, the heterogeneity of both size distribution and surface modification/property of nanomaterials is also unavoidable. Third, the environmental susceptivity of nanomaterials was studied, and the results showed that spectroscopic properties of the above three nanomaterials are all sensitive to the pH change of solution. Moreover, AuNPs are also rather susceptible to the ionic strength of solution. The above three problems should arouse high attention of researchers in some bioanalyses. In addition, the measures that we suggested in the paper may be helpful to solve these problems to some extent.

Key words: nanomaterials, CdTe quantum dots, Au nanoparticles, carbon nanodots, toxicity, microscopic heterogeneity, environmental susceptivity, bioanalysis