利用无机低温水相合成法制备表面包覆L-半胱氨酸的CdTe/ZnTe核壳型量子点, 测量不同溶液以及激发功率激光作用下该量子点的光谱特性。 结果表明, 该量子点吸收谱和荧光光谱峰值位置不随pH值变化, 而荧光光强随pH值升高呈近似线性上升趋势; 不同缓冲液对该量子点荧光光强无影响, 但随孵育时间延长, 荧光强度略有下降; 在强激光照射下QDs会被快速光漂白, 选择适当的激光功率(<100 μW), 可降低漂白速率, 实现长时间稳定测量。 因此, 该量子点具有较好的生物稳定性和光稳定性, 将其与血铁蛋白相连形成靶向共轭纳米粒, 可成功用于HeLa细胞标记。 细胞内量子点光漂白实验表明, 细胞微环境会影响量子点的光稳定性, 加速量子点的光漂白。

Water-soluble CdTe/ZnTe core-shell quantum dots (QDs) coated with L-cysteine were synthesized in low-temperature aqueous-phase one-pot approach. The authors measured the spectral characteristics of QDs at different pH in various buffer solutions and under different excitation laser powers. The primary results show that the absorption spectra of QDs approximately overlap and the fluorescence spectra peaks have no shift in different pH solution. The fluorescence intensity increased linearly with increasing pH. With the incubation time in borate buffer solution, the fluorescence intensity decreased a little. Under strong power laser, the QDs were photobleached rapidly. However, QDs are strongly anti-photobleaching under appropriate laser power (＜100 μW). Thus, such QDs have good biological stability and optical stability. By conjugating the QDs with transferrin protein and constructing the targeted fluorescent nanoparticles, the authors labelled the HeLa cell successfully. Photobleaching experiments in vivo show that microenvironment inside cells affect the stability and accelerate the photobleaching of QDs.