A colorimetric hydrogel biosensor for rapid detection of nitrite ions

Nitrite ions are important markers of inflammation, food safety, and water quality; therefore, various methods are under development to detect nitrite ions. This paper describes a novel method for detecting nitrite ions using polyethylene glycol (PEG) hydrogel superimposed glass fiber membrane strips. A colorimetric Griess assay was performed on the hydrogel modified with N-(1-naphthyl)ethylenediamine by dropping a solution of nitrite and sulfanilamide. This colorimetric hydrogel sensor exhibited a detection limit as low as 10 μM for nitrite ions and the working concentration of nitrite ions was between 10 μM and 5 mM. The colorimetric reaction was completed within a few seconds; the performance test results indicated that the sensor was specific to nitrite ions compared to other anions, and it was suitable to detect nitrite ions in clinical samples. In the future, this sensor platform can be used to detect nitrite ions in various complex solutions including biological and environmental samples.