An ESIPT-based NIR-fluorescent probe for exosome labeling and in situ imaging

Exosomes play significant roles in physiological and tumorigenic processes and it is desirable to visualize and track the exosomes.Herein,a novel amphiphilic fluorescent probe HBT-Exo based on excited-state intramolecular proton transfer(ESIPT)mechanism is reported for exosome-labeling.Its ESIPT characteristics were confirmed by both theory calculation and experimental observation,which enable the probe to show a large Stokes shift as well as near-infrared(NIR)keto-form emission.HBT-Exo displayed excellent biocompatibility and remarkable efficiency for exosome-labeling in gastric cancer cells.Furthermore,the labeled exosomes were successfully applied for the real-time in situ imaging in mouse models.

The exquisite integration of ESIPT, PET and AIE for constructing fluorescent probe for Hg(II) detection and poisoning

Excessive mercury ions(Hg^(2+)) in the environment can accumulate in human body along with the food chain to cause serious physiological reactions.The fluorescence probes were considered as convenient tool with great potential for Hg^(2+) detection.Most existing probes suffer from aggregation-induced quenching(ACQ) effects and insufficient sensitivity.Herein,a novel type of fluorophore was developed by combining the aggregation-induced emission(AIE) and excited state intramolecular proton transfer(ESIPT) characteristics.Subsequently,a phenyl thioformate group with photoinduced electron transfer(PET)effect was connected to give an efficient "turn-on" probe(HTM),which exhibited good selectivity toward Hg^(2+),short response time(30 min),coupled with extremely low detection limit(LOD=1.68 nmol/L).In addition,HTM was used successfully in real samples,cells and drug evaluation,underlying the superiority of HTM to detect Hg^(2+) in practical applications.

Monitoring intracellular pH fluctuation with an excited-state intramolecular proton transfer-based ratiometric fluorescent sensor

Intracellular pH is a key parameter related to various biological and pathological processes.In this study,a ratiometric pH fluorescent sensor ABTT was developed harnessing the amino-type excited-state intramolecular proton transfer(ESIPT) process.Relying on whether the ESIPT proceeds normally or not,ABTT exhibited the yellow fluorescence in acidic media,or cyan fluorescence in basic condition.According to the variation,ABTT behaved as a promising sensor which possessed fast and reversible response to pH change without interference from the biological substances,and exported a steady ratiometric signal(I_(478)/I_(546)).Moreover,due to the ESIPT effect,large Stokes shift and high quantum yield were also exhibited in ABTT.Furthermore,ABTT was applied for monitoring the pH changes in living cells and visualizing the pH fluctuations under oxidative stress successfully.These results elucidated great potential of ABTT in understanding pH-dependent physiological and pathological processes.