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

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.