Construction of fluorescent rotors with multiple intramolecular rotation sites for visualization of cellular viscous compartments with elevated fidelity

A fluorescent probe for detecting mitochondrial viscosity and its application in distinguishing human breast cancer cells from normal ones

Mitochondrial viscosity is closely associated with intracellular physiological activities yet their abnormality will result in various diseases. In particular, viscosity in cancer cells is different from that in normal cells, which is thought to be an indicator for cancer diagnosis. However, there were few fluorescent probes able to distinguish homologous cancer and normal cells by detecting mitochondrial viscosity. Herein, we designed a viscosity-sensitive fluorescent probe (named NP) based on the twisting intramolecular charge transfer (TICT) mechanism. NP exhibited exquisite sensitivity to viscosity and selectivity to mitochondria and excellent photophysical properties, such as large Stokes shift and high molar extinction coefficient, which enables wash-free, high-fidelity and fast imaging mitochondria. Moreover, it was capable of detecting mitochondrial viscosity in living cells and tissue, as well as monitoring apoptosis process. Significantly, considering numerous breast cancer cases in every country of the world, NP was successfully applied to distinguish human breast cancer cells (MCF-7) from normal cells (MCF-10A) by difference in fluorescence intensity originated from abnormality in mitochondrial viscosity. All the results indicated that NP could serve as a robust tool for effectively detecting mitochondrial viscosity changes in-situ.

A sensitive bio-probe for tracking lipid droplets with large Stokes shift and its application in cell imaging

Lipid droplets (LDs) including triacylglycerols and cholesteryl esters are applied for protein transformation and protein maturation in living bodies, which have an important effect on lipid metabolism, homeostasis, and interactions with other organelles. The imbalance of LDs could lead to many serious diseases including insulin resistance, cancer, obesity, liver disease, cardiovascular disease, and neurodegenerative disease. The diameter distribution of LDs is quite extensive from 100 nm to 100 µm. Herein, we designed and constructed a novel organic bio-probe TzAr-N for LDs cell imaging with much more hydrophobic and viscous environment compared to cytosol by using 1,3,5-triazine as electron acceptor. This sensitive probe exhibited favorable merits including large Stokes shift (almost 80 nm), good LDs targeting ability, and a low biological toxicity, which also could not be affected by wide range of pH values. Furthermore, the bio-probe TzAr-N could also mark LDs distribution in living HeLa cells.