Graphene quantum dots based fluorescent biosensor for nitrogen detection of urea fertilizer

Abstract

A simple and fast fabrication of fluorescent biosensor based on graphene quantum dots (GQDs) for agricultural application is presented. Graphene oxide was used as a starting material for GQDs synthesis by hydrothermal method. Optical properties and morphology of the synthesized GQDs were characterized by UV-Vis, photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM). The results showed that the synthesized GQDs exhibited spherical shape with their average diameter of 5.70 nm. The UV-Vis and PL spectra showed typical adsorption peak and maximum emission peak of the synthesized GQDs at 330 nm and 472 nm, respectively. To study sensing performance of fluorescent biosensor for nitrogen detection, aqueous solution of GQDs was mixed with different concentrations of nitrogen solution. According to PL spectra result, it is found that PL intensity of GQDs solution significantly increased corresponding to higher concentrations of nitrogen solution. This result suggests that fluorescent biosensor based on GQDs may be an alternative technique for primary nutrient detection in soils.