Related Experiment Video
Updated: Jan 27, 2026

Use of the Protease Fluorescent Detection Kit to Determine Protease Activity
Published on: August 4, 2009
Ratiometric Fluorescent Hydrogel Test Kit for On-Spot Visual Detection of Nitrite
Yuanjin Zhan1, Yanbo Zeng2, Lei Li2
1Institute of Nanomedicine and Nanobiosensing, MOE Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, College of Chemistry , Fuzhou University , Fuzhou 350116 , China.
Abstract:
In this work, we proposed a new method based on carbon dots (named m-CDs) for selective and efficient detection of nitrite (NO2-), which was based on the interaction between the amine group of m-CDs and NO2- via a diazo reaction that produced diazonium salts and induced the fluorescence quenching of m-CDs. The concentration of NO2- shows a good linear relationship with a quenched fluorescence intensity from 0.063 to 2.0 μM ( R2 = 0.996) with a detection limit of 0.018 μM. In addition, a ratiometric fluorescence probe ( m-CDs@[Ru(bpy)3]2+) was constructed via electrostatic interaction by introducing Ru(bpy)3Cl2·6H2O as an internal reference fluorescent reagent. Interestingly, a transition of the fluorescent color of the ratiometric probe from cyan to red could be visually observed upon increasing the concentration of NO2-. Based on these findings, a ratiometric fluorescent-based portable agarose hydrogel test kit was fabricated and applied for on-spot assessment of NO2- content within 10 min. As far as we know, this is the first ratiometric fluorescent sensor for visual detection of NO2-. It has broad application prospects in environmental monitoring and food safety assessment.
Related Concept Videos
Visual System
Once through the pupil, the light passes through the lens, a...
Visual Agnosia
Photoreceptors and Visual Pathways
Detection of Gross Error: The Q Test
Photoluminescence: Fluorescence and Phosphorescence
A pair of electrons in a...
Atomic Fluorescence Spectroscopy

