Sensitive and selective detection of nitrite ion based on fluorescence superquenching of conjugated polyelectrolyte

In recent years, conjugated polyelectrolytes (CPEs) that feature good water-solubility have drawn great attention as optical transducers in high sensitive bio- and chemo-sensors due to their predominant optical/electronic properties and remarkable signal amplification. Herein, a sensitive and selective assay for nitrite ion has successfully been developed based on the fluorescence superquenching of an anionic CPE, PPESO(3). With the sensor format composed of PPESO(3) and H(+), Fe(2+) can easily be oxidized into Fe(3+) in the presence of NO(2)(-), and the later dramatically quenches the fluorescence of PPESO(3). Indeed, the inclusion of conjugated polyelectrolyte into the sensory scheme can give rise to a notable enhancement of fluorescence response, which endows the newly proposed NO(2)(-) probe with high sensitivity. Thus, nitrite ion within a relatively wide concentration range (0-70 microM) can be determined in a rather simple and sensitive manner with a detection limit of 0.62 microM (approximately 28 ppb). Additionally, most other anions such as halogen ions, acetate, sulfate, carbonate, phosphate and even nitrate, show minor interference on the NO(2)(-) detection.