Nanomolar level electrochemical detection of glycine on a miniaturized modified screen-printed carbon-based electrode: a comparison of performance with glassy carbon electrode system.

In this work, we demonstrate the electrochemical (EC) sensing of glycine (GLY) on a gold-copper nanocluster on nitrogen-doped graphene quantum dot-modified (indigenously fabricated) screen-printed electrode (AuCuNC@N-GQD/SPE). SPE was fabricated by step-by-step printing of reference, working, and counter electrodes to develop an all-printed SPE. A comparison strategy between SPE and the glassy carbon electrode (GCE) towards the EC sensing of GLY was carried out. The sensing performance was enhanced while replacing GCE with SPE. The limit of detection (LOD) for GLY obtained by EC sensing with AuCuNC@N-GQD/GCE was 10 nM and that with AuCuNC@N-GQD/SPE was 10 times lower, 1 nM, and is the lowest LOD value reported hitherto. Compared with AuCuNC@N-GQD/GCE, the current response of AuCuNC@N-GQD/SPE exhibited a ∼2.6-times enhancement with a sensitivity of 0.206 μA μM cm. Thus, the successful shift from GCE to SPE not only miniaturizes the sensor device but also enhances the electrochemical detection performance.