Heterostructured CuO/g-C3N4 nanocomposite-based molecularly imprinted electrochemical sensor for the detection of microcystin-LR.

Abstract

Microcystin-LR (MC-LR) is one of the most toxic liver-damaging toxins that can be produced during cyanobacteria blooms and poses a threat to human health, emphasizing the need for new detection methods. A molecularly imprinted electrochemical sensor was developed for the detection of MC-LR based on a copper oxide and graphitic carbon nitride (CuO/g-C3N4) nanocomposite. CuO/g-C3N4 nanocomposite is synthesized using an in situ growth method wherein the CuO nanoparticles are homogenously dispersed on g-C3N4 nanosheets, forming a CuO/g-C3N4 p-n heterojunction. This composite effectively facilitates the charge transfer process while significantly enhancing the detection signal intensity. A molecularly imprinted polymer (MIP) film was directly prepared on the surface of a CuO/g-C3N4 coated glassy carbon electrode via free-radical polymerization using MC-LR as a template along with suitable functional monomers. Following template removal, the resulting molecularly imprinted cavities within the MIP demonstrated high specificity for MC-LR recognition. The MIP-based electrochemical sensor exhibited an excellent linear response and high sensitivity for MC-LR detection over a broad concentration range of 0.2-300 ng mL-1, achieving a low limit of detection (LOD) of 0.08 ng mL-1 (calculated using 3σ/S). The sensor demonstrated excellent selectivity, reproducibility, and stability for the rapid and ultrasensitive detection of MC-LR, thereby providing a critical analytical capability for safeguarding environmental quality and public health.