Sensitive fluorescence turn-on sensing of hydroxyl radical and glucose based on the oxidative degradation of reductive organic cage

Abstract

The accurate and sensitive quantification of hydroxyl radical (·OH) and glucose is necessary for disease diagnosis and health guidance, but still challenging owing to the low concentration of ·OH and poor water solubility of fluorescent probes. In addition, fluorescent probes may cause secondary pollution to the environment. Here an organic cage was reported as a sensitive fluorescent probe for ·OH and glucose in aqueous solution without serious secondary pollution. The prepared organic cage with good water solubility showed specific redox affinity to ·OH in acidic condition, resulting in two oxidation stages of mild oxidation and subsequent oxidative degradation. Fluorescence around 485 nm enhanced remarkably in the first stage, and benzene ring in organic cage was degraded in the second stage. Based on the significant fluorescence enhancement, a sensitive fluorescence turn-on sensing method for ·OH was established within 90 s with the limit of detection (3s/k, where s and k are the standard deviation for 10 replicate detections of blank and the slope of calibration function) of 5 nM. The recoveries of spiked ·OH in human serum and water samples ranged from 95.2 % to 102.7 %. After the glucose oxidase enzyme-Fenton reaction was involved, the ·OH detection was also applied to sensitive sensing of glucose with the limit of detection (3s/k) of 6 nM. The recoveries of spiked glucose in sugary drinks ranged from 96.2 % to 102.6 %. Furthermore, the proposed method would also be suitable for other hazardous substances and biomarkers which can produce hydrogen peroxide and further form ·OH via Fenton reaction.