A new ratiometric and colorimetric fluorescent probe HTD was synthesized based on the reaction of 4-aminophenyl boronic acid pinacol ester and 4-(3-formyl-4-hydroxyphenyl) benzonitrile. The probe exhibited a unique fluorescence response to hypochlorous acid and had good anti-interference performance in the presence of other interference. When HTD met the NaClO, the light orange fluorescence was changed to green with the blue-shifted emission wavelength from 550 to 500 nm. Moreover, the absorbance of HTD’s UV–vis at 300 nm and 375 nm decreased in the presence of NaClO. The limit of detection was 1.83 × 10 –7 M and 2.96 × 10 –6 M based on the fluorescence and UV–vis titration data. NMR, HRMS, and IR spectra suggested that the possible sensing mechanism of HTD to NaClO was the formation of initial compound 4-(3-formyl-4-hydroxyphenyl) benzonitrile due to the oxidation of hypochlorous acid in aqueous solution. The portable test strips were obtained, and the real water sample test reached good results with spiking recoveries among 92.00% ~ 103.25%. Finally, endogenous hypochlorous acid produced by LPS and PMA was successfully detected by HTD in living mice using in situ fluorescence bioimaging. Graphical abstract
Yaqiong Zhang,Junping Lv,Qin Zhou,Kaile Chu,Min Li,Yayuan Li,Jie An,Zhifang Wu,Sijin Li
Ratiometric fluorescent (RF) sensors, leveraging their inherent calibration mechanism, can greatly reduce the interference of irrelevant factors and exhibits superior detection sensitivity and more attractive visual detection effects in the process of quantitative analysis. Up to now, there are few probes that can detect fluorine by the proportional fluorescence signal. Herein, we constructed a RF probe for determination of fluorine by confining self-synthesized red emitting organic small molecules 10-(diethylamino)-3-hydroxy-5,6-dihydrobenzo[ c ]xanthen-12-ium (HTD) into the microchannels and cavity structures of UiO-66-NH 2 , exhibiting two emission maxima at 428 nm and 616 nm, respectively. After introducing fluoride into the system of probe, a drastic fluorescence enhancement at 428 nm was emerged, whereas the emission peak at 616 nm underwent minor fluctuations. The probe that has been developed enables the sensitive and selective detection of fluoride ions, exhibiting excellent linear relationships in the range of 0–100 μM. The detection limit value was estimated to be 6.93 μM. This unique ratiometric luminescence behavior of probe toward fluoride resulted from the creation of hydrogen bonds between fluoride and amino groups in HTD@UiO-66-NH 2 . Notably, the probe could utilize as an effective tool for detecting fluoride in cells with high-quality results, which could have important implications for research in biology, toxicology, and related fields. Simultaneously, its corresponding portable online test strips can be easily acquired and employed for fluoride detection through visual colorimetric analysis. The proposed method offers an alternative technology for quantifying fluoride levels in real-life water samples.
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