CuO@AgNPs nanozyme cavity arrays on screen-printed electrodes for ultrasensitive and on-site SERS detection

The research on the use of metal–semiconductor hybrid systems for constructing chemical and biological sensors has received increasing attention. In this work, a screen-printed electrode (SPE) with peroxidase activity was developed using AgNPs decorated CuO cavity array (CuO@Ag SPE) for on-site SERS detection of Leuco crystal violet (LCV) in aquatic products. The low Michaelis-Menten constant (Km = 42.8 μM) and the high maximum reaction velocity (Vm = 5.1 × 10−8 mol·L−1s−1) indicate that the CuO@Ag SPE has a strong affinity and excellent catalytic efficiency. Moreover, this substrate has a considerable SERS enhancement with EF of 6.1 × 106, resulting from the synergetic effect of the electromagnetic enhancement (EM) and chemical enhancement (CM) after modifying noble metal onto semiconductor materials. The CuO@Ag SPE can efficiently catalyze the oxidation of the Raman-inactive reporter (LCV) and simultaneously act as SERS-active substrates for detecting the generated Raman-active crystal violet (CV), providing a relatively wide linear range (2.0 nM-2.0 μM) and a lower detection limit (0.3 nM). The recoveries obtained from the proposed SPE range from 100.1 to 109.2% and RSD from 4.9 to 10.4%, demonstrating that the SPE has high accuracy and reliability in real sample detection.