This review comprehensively summarizes and highlights recent progresses in the design and application of small molecule based fluorescent probes for sensing and imaging the microenvironment within specific cellular regions since 2015.

Elucidating the internal relationship between diseases and mitochondrial viscosity remains a great challenge due to the lack of the studies on multidisease living animals. So far, demonstrating abnormal mitochondria viscosity in the fatty liver and tumor living mice has not been achieved. To address this critical challenge, the powerful two-photon and mitochondria-targeted fluorescence probe CBI-V was designed herein for viscosity detection with deep red emission. Utilizing the new probe CBI-V, the mitochondrial viscosity alteration in living systems caused by monensin or nystatin has been monitored sensitively and selectively in real time. Moreover, the probe is capable of imaging mitochondrial viscosity in the inflammatory models at the cell, zebrafish, and mice level. Importantly, the visualization of mitochondrial viscosity has been achieved in both fatty liver and tumor living mice for the first time. This work not only advances the study of the relationship between disease and mitochondrial viscosity but also opens up an efficient way for diagnosing mitochondrial viscosity related diseases.

This review highlights the design strategies of typical organic fluorescent probes for reactive carbonyl species and their application in biological imaging.

We have rationally designed a robust fluorescent probe CTPA for potential cancer diagnosis by monitoring LD numbers and polarity variation. With the outstanding solvatochromism and high specificity for LDs of CTPA, the diagnosis of cancer can be achieved not only at the cellular levels but also in organs and living mice for the first time.

The recent progress in the development of organic fluorescent probes for monitoring the autophagy process in living cells has been reviewed for the first time.