Lysosome-targeted ratiometric fluorescent sensor for monitoring pH in living cells based on one-pot-synthesized carbon dots

Abstract

Ahydrothermal method has been employedto synthesize a green and one-pot carbon dots-based sensor for ratiometric monitoring and imaging lysosomal pH in living cells. The carbon dots were directly functionalized by abundant amino groups during synthesis and exhibited dual emission bands at 439 and 550nm under single-wavelength excitation of 380nm without any additional modification. In addition to its small size, the established sensor had good biocompatibility. Owing to its abundant amino groups and good hydrophilicity, the sensor is able totarget lysosome with high Pearson's colocalization coefficients (0.935 and 0.924) and responds to change of lysosomal pH in living cells. It also had excellent pH sensitivity and reversibility, and anti-interference capability, thus enabling sensing pH change in intracellular environment in real time, as demonstrated by successful monitoring of lysosomal pH changes during lysosomal alkalization, dexamethasone-induced stimulation, and stress in Michigan Cancer Foundation-7 cells (blue channel, excitation = 405nm and emission = 419-459nm bandpass; and yellow channel, excitation = 405nm and emission = 530-570nm bandpass). Graphical abstract.