Hexi Wei, Yangtao Shao, Xubin Wang, Yan Luo, Mengyu Ji, Ruijuan Wen, Rongrong Huang*, Xiaogang Liu*, Yu Fang*. Anal. Chem. 2025, DOI: 10.1021/acs.analchem.5c05140

Nitrite, a widely used food preservative and industrial additive, has long been associated with its benefits in food safety and preservation. However, the World Health Organization (WHO) has reported that excessive accumulation of nitrite poses serious health risks, including carcinogenic and toxic effects. This underscores the urgent need for reliable and efficient detection methods to monitor nitrite levels and safeguard public health.

Figure 1. Schematic illustration for the design strategy of the sensing fluorophore DAPA-1CB and its sensing performance towards nitrite.

Figure 2. Sensing performance for the detection of nitrite.

In this study, we reported the development of an o-carborane-based fluorophore, DAPA-1CB, which was strategically designed by integrating o-carborane units into a DAPA (diaminophenylalanine) skeleton. Compared to the reference compound DAPA-2CB, the specific functional group (-NH₂) was maintained in DAPA-1CB for specific interactions with nitrite. The modification with the o-carborane unit not only enhances photostability but also significantly increases the Stokes shift of the compounds, which is critical for effective and reliable fluorescence detection. Our results demonstrate that DAPA-1CB exhibits exceptional sensitivity and selectivity for nitrite detection, with detection limits as low as 85 nM in fluorescence mode and 34 nM in colorimetric mode. Furthermore, DAPA-1CB successfully distinguishes nitrite from other potential interferences, making it a promising candidate for real-world applications. Notably, this probe has been successfully applied to detect nitrite in food samples, such as pickles, bacon, and smoked fish, with high recovery rates, confirming its practical applicability in food safety monitoring.

First Author: Wei Hexi, doctoral candidate, Shaanxi Normal University

Correspondence Authors: Postdoc Researcher Huang Rongrong, Singapore University of Technology and Design; Assoc. Prof. Liu Xiaogang, Nanyang Technological University; Prof. Fang Yu, Shaanxi Normal University

Full Text Link: https://doi.org/10.1021/acs.analchem.5c05140