Pyo Kyunglim, Ly Nguyen Hoang, Han Sang Myeong, Hatshan Mohammad Bin, Abuhagr Abubkr, Wiederrecht Gary, Joo Sang-Woo, Ramakrishna Guda, Lee Dongil
Department of Chemistry , Yonsei University , Seoul 03722 , Korea.
Department of Chemistry , Soongsil University , Seoul 06978 , Korea.
J Phys Chem Lett. 2018 Sep 20;9(18):5303-5310. doi: 10.1021/acs.jpclett.8b02130. Epub 2018 Sep 5.
Accurate measurements of intracellular pH are of crucial importance in understanding the cellular activities and in the development of intracellular drug delivery systems. Here we report a highly sensitive pH probe based on a fluorescein-conjugated Au nanocluster. Steady-state photoluminescence (PL) measurements have shown that, when conjugated to Au, fluorescein exhibits more than 160-fold pH-contrasting PL in the pH range of 4.3-7.8. Transient absorption measurements show that there are two competing ultrafast processes in the fluorescein-conjugated Au nanocluster: the intracore-state relaxation and the energy transfer from the nonthermalized states of Au to fluorescein. The latter becomes predominant at a higher pH, leading to dramatic PL enhancement of fluorescein. In addition to the intrinsically low toxicity, fluorescein-conjugated Au nanoclusters exhibit high pH sensitivity, wide dynamic range, and excellent photostability, providing a powerful tool for the study of intracellular processes.
精确测量细胞内pH值对于理解细胞活动以及细胞内药物递送系统的开发至关重要。在此，我们报告一种基于荧光素共轭金纳米簇的高灵敏度pH探针。稳态光致发光（PL）测量表明，当与金共轭时，荧光素在4.3 - 7.8的pH范围内表现出超过160倍的pH对比PL。瞬态吸收测量表明，荧光素共轭金纳米簇中存在两个相互竞争的超快过程：核心态弛豫和从金的非热态到荧光素的能量转移。后者在较高pH值时占主导地位，导致荧光素的PL显著增强。除了本质上的低毒性外，荧光素共轭金纳米簇还表现出高pH敏感性、宽动态范围和出色的光稳定性，为研究细胞内过程提供了一个强大的工具。
