Self-assembly of silver nanoparticles on chitosan/polyvinylpyrrolidone modified micro-needle electrode for amperometric detection of nitrate in seawater

Abstract

In this work, silver nanoparticles (AgNPs) were self-assembled on the micro-needle electrode (MNE) with the help of chitosan (CTS) and polyvinylpyrrolidone (PVP) and used for the amperometric (i-t) determination of nitrate (NO3–) in seawater samples. CTS/PVP was electrodeposited on the MNE surface to improve the conductivity and specific surface area of the MNE, and to provide reduction conditions needed for Ag+ reduction and strong binding affinity for combination of AgNPs which had excellent catalytic activity for NO3–. AgNPs were self-assembled uniformly on the surface of MNE with the diameter of about 150–400 nm. Thanks to the unique aciform structure of MNE, the outstanding adhesion ability of CTS/PVP, and the excellent electrocatalytic ability of AgNPs, the so-prepared AgNPs/CTS/PVP/MNE showed significantly improved performance and stability for the amperometric determination of NO3–. Under the optimal conditions, the AgNPs/CTS/PVP/MNE was found to have a wide linear range (5–2000 μM) and a low limit of detection (1.2 μM). Furthermore, the AgNPs/CTS/PVP/MNE was successfully used for the direct determination of NO3– in coastal seawater samples with satisfactory results.