Polarity-Targeted\nCarbon Dots for Mitochondria and\nLysosomes Imaging

Normally, electrostatic-dependent mitochondria localization\ncan\ncause a decrease/loss of mitochondrial membrane potential (MMP), leading\nto the corresponding abnormal behaviors. So, achieving subcellular\norganelle localization and imaging with as little interference on\ntheir physiological activity is of significance for understanding\ncell activity. Herein, we discover and demonstrate that “polarity”\ncan independently act as a novel kind of target for labeling at the\norganelle level. On this basis, mitochondria and lysosomes are precisely\nfluorescently imaged by two kinds of polarity-targeted carbon dots\n(C-dots), respectively. The two C-dots, named C-dots-1 and C-dots-2,\nhave almost identical size and morphology as well as surface chemistry.\nThe subtle difference is their polarity property: both of them are\namphiphilic, with 1.54 and 0.95 for the log P values. Different from\ncommonly used cationic-based organelle probes, both of the two C-dots\npossess slightly negatively charged surfaces (ζ-potential values\n∼ −2.5 to −7.5 mV) at physiological conditions.\nInterestingly, the C-dots-1 and C-dots-2 have the capacity for highly\nselectively labeling and imaging mitochondria and lysosomes, whether\ncancer cells or normal cells. Because the targeting processes do not\nrely on electrostatic attraction effects, the MMP is not changed during\nlocalization processes. So, the corresponding cell abnormal behaviors\ncaused by MMP diminishing, for example, the autophagy phenomenon,\ncan be effectively avoided.