Fabrication and characterization of a fluorescent sensor based on Rh 6G-functionlized silica nanoparticles for nitrite ion detection

In this paper, a rhodamine derivative of p-hydroxybenzaldlehyde rhodamine 6G hydrozone (denoted as Rh 6G-OH) is covalently grafted onto the surface of silica nanoparticles, giving a novel fluorescent chemosensing hybrid material (denoted as Rh 6G-SiO2) for the detection of nitrite ion. The FT-IR spectra confirm that Rh 6G-OH has been successfully grafted onto the surface of SiO2 nanoparticles, which effectively prevents the sensing probe leakage out of SiO2 supporting matrix. Rh 6G-SiO2 sensor shows a good linearity between the fluorescence intensity of Rh 6G-SiO2 and the concentration of nitrite ion with a detection limit down to 1.2 μM, which results from a dramatic fluorescence reducing by the addition of nitrite ion upon the suspension of Rh 6G-SiO2. A high selectivity for nitrite ion in the presence of interference ions is demonstrated. The sensing mechanism of Rh 6G-SiO2 toward nitrite ion is discussed in detail and found to be a static quenching process.