Compact device prototype for turn-on fluorescence detection of sarin based on reactive 4,4-diaryloxy-BODIPY derivatives. Lu Liu#, Sheng Li#, Wendan Luo, Jiashuang Yao, Taihong Liu*, Molin Qin*, Zhiyan Huang*, Liping Ding, and Yu Fang. Sens. Diagn. 2024, 3, 1651-1658. Doi: 10.1039/D4SD00228H.

Nerve agents, listed as lethal weapons of mass destruction due to their extreme toxicity and devastating effects by OPCW, can pose a serious threat to the global security and public health. Therefore, developing in-situ, real-time, efficient, and practical analysis technologies and portable devices is of great strategic significance for detecting chemical warfare agents and guiding emergency response. Of course, all related progresses should be based on the efficient sensor technologies. It is worth noting that some literatures generalized the concept of sensors, and even refer to a molecule with sensing or analytical functions as a sensor. In principle, a sensor should be a device usually composed of sensitive components and conversion components, can sense and convert the specific measured signal into usable output signal according to a certain pattern. Thanks to satisfying in-situ and real-time detection, fluorescent film sensors have attracted increasing attention and evolved into a new generation of super-sensitive portable analytical technique after ion mobility spectroscopy (IMS). Based on the research progresses of our group, this article provides an researche example on fluorescent film sensors (FFSs) specially for detecting nerve agents.

图1. 叠层管式荧光传感器实物图（a）与结构示意图（b）；由控制系统、传感单元、数据处理系统组成的原型传感平台的结构示意图（c）及真实传感测试场景图（d）。

Development of fluorescence indicators for efficient and accurate detection of lethal nerve agents has evoked extensive interest recently. Herein, we presented two spiranic 4,4-diaryloxy-BODIPY derivatives for efficient and fluorescence turn-on detection of sarin in solution media. A colorimetric mode featured the merits of obvious color changes from dark to greenish fluorescence under UV light. The generated new fluorescence emissions reached their maxima within several minutes and the peaks were assigned to the generated by-product oxo-BDP with a fluorescence quantum yield (Φ_F) ∼ 20% in acetonitrile. The detection limits of two 4,4-diaryloxy-BODIPYs for a simulant diethylchlorophosphate (DCP) were determined to be 13.2 nM and 8.2 nM, respectively. The underlying sensing mechanism was clarified as the synergistic effect of 4,4-bond cleaving and fluorescence turn-on related to the photoinduced electron transfer process.

Figure 2. (a) Response traces of OBP2 in ACN to different concentrations of GB conducted by the home-made compact device prototype. (b) Response plot and linear fitting of OBP2 to different concentrations of GB. Fluorescence color changes of compound OBP1 (c) and OBP2 (d) to sarin (GB).

Furthermore, a compact tubular sensor and a sensing platform prototype were fabricated properly. Superior detection results and further evaluation for real samples and simulants could be conducted at the sub-mM level on-site. Successful trials aid in understanding the structure–function relationship of 4,4-disubstituted BODIPY chromophores as well as the future development of a miniaturized device prototype for on-site detection of chemical warfare agents.

This work has been published in the Journal of Sensors & Diagnostics as an invited paper from the editor-in-chief, and the abstract figure selected as the feature cover for the current issue.

First Authors: Liu Lu and Li Sheng, Master’s candidates, Shaanxi Normal University

Correspondence Authors: Assoc. Prof. Liu Taihong, Shaanxi Normal University; Dr. Qin Molin, State Key Laboratory of NBC Protection for Civilian; Assoc. Prof. Huang Zhiyan, Shaanxi Normal University

Full Text Link: https://doi.org/10.1039/d4sd00228h