posted on 2021-09-20, 14:36authored byHuihui Yang, Jun Chen, Yuling Liang, Yanfei Zhang, Wen Yin, Yuzhi Xu, Si-Yang Liu, Zong Dai, Xiaoyong Zou
Dynamic imaging of cell surface pH is extremely challenging due
to the slight changes in pH and the fast diffusion of secreted acid
to the extracellular environment. In this work, we construct a novel
metal–organic framework (MOF)-shell-confined i-motif-based
pH probe (MOFC-i) strategy that enables sensitive and dynamic imaging
of cell surface pH. The CY3- and CY5-labeled i-motif, which is hybridized
via its short complementary chain with two-base mismatches, is optimized
for sensing at physiological pH. After efficiently anchoring the optimized
pH probes onto the cell membrane with the aid of cholesterol groups,
a biocompatible microporous MOF shell is then formed around the cell
by cross-linking ZIF-8 nanoparticles via tannic acid. The microporous
MOF shell can confine secreted acid without inhibiting the normal
physiological activities of cells; thus, the MOFC-i strategy can be
used to monitor dynamic changes in the cell surface pH of living cells.
Furthermore, this method can not only clearly distinguish the different
metabolic behaviors of cancer cells and normal cells but also reveal
drug effects on the cell surface pH or metabolism, providing promising
prospects in pH-related diagnostics and drug screening.