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-Photosensitizers' dual functions in photodynamic cancer therapy and ClO- detection
We designed and synthesized the thionated NpImidazole derivatives BS and NS, new heavy-atom-free photosensitizers, which efficiently generates a triplet excited state with high singlet oxygen quantum yield. The introduction of C=S bond to NpImidazole core is essential for increasing spin-orbit coupling (SOC). The fluorescence emission of BS and NS were quenched at standard ambient temperature, accompanying with the increase of ISC process from the singlet states to triplet excited states via thionation. BS and NS showed negligible dark cytotoxicity against HeLa cells in working concentration. In the contrast, BS and NS rapidly induced cell death under blue light irradiation both in normoxia and hypoxia condition. Our current study demonstrates that C=S group can play an important role in type I ROS generation of PSs, which have unprecedented in the previous reports. Finally, the photophysical changes was assigned to the oxidative desulfurization of C=S group of BS and NS to C=O group of the corresponding BO and NO via hypochlorite. The combined results demonstrated the dual function of BS and NS as a fluorescent imaging agent for ClO- and an anti-cancer therapeutic by PDT that showed the potential strategy for “one-for-all” as well as multifunctional agents.
-aza-BODIPY based NIR fluorescent and colorimetric probe for selective cysteine detection
Cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) are essential biothiols for cellular growth, metabolism, and maintenance of biological system. Thus, the detection of biothiols is highly important for early diagnosis and evaluation of disease progression. In this article, a series of sulfonyl aza-BODIPY was synthesized, characterized, and examined by 1H-NMR, 13C-NMR, crystallization, photophysical properties and DFT calculation. Among these structures, a fluorescent probe (BDP-1), exhibited selective detection of Cys among various biothiols via nucleophilic aromatic substitution mechanism and typical size of Cys molecules. BDP-1 showed color change and near-infrared (NIR) fluorescent enhancement after reaction with Cys to generate BDP-OH, confirmed by HRMS. The red shift of absorption wavelength showed a similar tendency resulting in time-dependent density functional theory (TD-DFT). Furthermore, the calculated detection limit of BDP-1 toward Cys was 5.23 μM. This probe facilitates the colorimetric and fluorescent detection of Cys over other biothiols.
-Ratiometric fluorescence based chemosensor for the chiral recognition of carboxylates
Fluorescence
chemosensors to sense chiral molecules have been actively studied in recent
years. In the current study, we report naphthoimidazolium-cholesterol
derivative (NI-chol 1) as a fluorescence based chemosensor for chiral
recognition, in which naphthoimidazolium serves not only as fluorophore but
also as a recognition moiety for anions via imidazolium (C-H)+--anion
binding and the cholesterol unit acts as a chiral barrier. In particular, NI-chol
1 displayed unique and distinct ratiometric changes with Boc-D-Phe, on the other
hand, Boc-L-Phe induced a negligible change. Furthermore, distinct downfield
shift (from 9.64 ppm to 9.96 ppm) of the imidazolium C-H peak were observed for
Boc-D-Phe (5 eq.) with severe broadening, which indicates strong ionic hydrogen
bonding between the C-H proton and carboxylate.
-Polydiacetylene-Based Colorimetric and Fluorometric Chemosensors
Polydiacetylenes (PDAs) have received increasing attention as smart materials owing to their unique properties. Upon addition of various stimuli, blue PDAs can undergo a colorimetric transition from blue to red along with a change from non-fluorescent to fluorescent. The optical changes can be readily detected by the naked eye and by using absorption and fluorescence spectrometers. These properties make PDAs excellent materials for use in platforms for sensing chemical or biological targets. In recent years, a number of biosensors and chemosensors based on the optical responses of polydiacetylenes have been reported.
-CO2 Sensing and Capture