Construction of minitype glutamate sensor for in vivo monitoring of l-glutamate in plant

l -glutamate ( l -Glu) is the basic unit for the synthesis of protein, metabolic substances and chlorophyll, and plays an important role in the carbon and nitrogen metabolism in plants. The in vivo monitoring of l -Glu level is of great significance to study the growth and development of plants. Although a variety of methods have been reported for the in vitro determination of l -Glu, there are very limited research focused on the determination of l -Glu in plants. Here we firstly report a simple method to construct a minitype glutamate sensor for in vivo monitoring of l -glutamate in cucumber. The minitype graphite rod electrode (GRE) allows its application for in vivo monitoring, and modification of Pt nanoparticles (PtNPs) and poly ( m -phenylenediamine) film (PMPD) significantly improves the sensitivity and anti-interference ability, and immobilization of the glutamate oxidase (GluOx) could effectively catalyze the l -Glu into a detectable H 2 O 2 . The resulting l -Glu sensor exhibits a good performance in terms of high sensitivity, good selectivity and excellent stability with a linear range of 2–550 μM and limit of detection (LOD) as low as 0.536 μM. More importantly, the as-developed sensor was successfully applied for the determination of l -Glu in cucumber juice and the in vivo monitoring of l -Glu level in cucumber fruit. We envision that the constructed sensor will show great potentials for studying the growth mechanisms of plants.