Dual-responsive fluorescence probe for measuring HSO3- and viscosity and its application in living cells and real foods

Design and Screening of Fluorescent Probes Based upon Hemicyanine Dyes for Monitoring Mitochondrial Viscosity in Living Cells

Viscosity, at the subcellular level, plays a crucial role as a physicochemical factor affecting microenvironment homeostasis. Abnormal changes in mitochondrial viscosity often lead to various diseases in the organism. Based on the twisted intramolecular charge transfer mechanism, four hemicyanine dye fluorescent probes (HT-SA, HT-SA-S, HT-Bzh, and HT-NA) were designed and synthesized for viscosity response. The single bond between the nitrogen-containing heterocycle and the carbon-carbon double in the structure of the probe bond served as the viscosity response site. Finally, the probe HT-Bzh was screened as the optimal mitochondrial viscosity probe according to its responsiveness, targeting, and interference resistance. The fluorescence intensity of the probe HT-Bzh increased 22-fold when the viscosity was increased from 13.75 to 811.2 cP. In summary, all four viscosity probes we have developed can be used in different applications depending on the external environment, providing a valuable reference for the design of potential tools to address viscosity monitoring in biological systems.

Carbazole-based mitochondria-targeted fluorescent probes for in vivo viscosity and cyanide detection in cells and zebrafish

Cells of most eukaryotic species contain mitochondria, which play a role in physiological processes such as cellular senescence, metabolism, and autophagy. Viscosity is considered a key marker for many illnesses and is involved in several crucial physiological processes. Cyanide (CN-) can target cytochrome-c oxidase, disrupting the mitochondrial electron transport chain and causing cell death through asphyxiation. In this study, a fluorescent probe named HL-1, which targets mitochondria and measures viscosity and CN- levels, was designed and synthesized. HL-1 is viscosity-sensitive, with a linear correlation coefficient of up to 0.992. In addition, HL-1 was found to change color substantially during a nucleophilic addition reaction with CN-, which has a low detection limit of 47 nM. HL-1 not only detects viscosity and exogenous CN- in SKOV-3 cells and zebrafish but also monitors viscosity changes during mitochondrial autophagy in real time. Furthermore, HL-1 has been used successfully to monitor changes in mitochondrial membrane potential during apoptosis. Endogenous CN- in plant samples was quantified. HL-1 provides new ideas for studying viscosity and CN-.