Cu- and Sn-Codoped Mesoporous BaTiO₃-G-SiO₂ Nanocomposite for Bioreceptor-Free, Sensitive, and Quick Electrochemical Sensing of Rhizopus stolonifer Fungus

Rhizopus stolonifer produces large postharvest losses that account for about 80% of total losses in prepackaged and loose tomato fruits from Rhizopus rot. In this study, we effectively synthesized a Cu- and Sn-codoped mesoporous BaTiO3–G–SiO2 (CuSnBTGS) nanocomposite by utilizing a simple, low-cost self-assembly method for the electrochemical detection of Rhizopus stolonifer fungus; this method does not require a biological or chemical receptor or antibodies. We focused on the microstructure design of CuSnBTGS in combination with Cu and Sn codoping, which is widely regarded as the most efficient way to produce high-performance electrodes. The resultant CuSnBTGS composite exhibited excellent electrochemical characteristics and remarkable performance in the direct detection of Rhizopus stolonifer (bread fungus) levels in contaminated solutions. The chronoamperometric response of the CuSnBTGS composite electrode was linear with Rhizopus stolonifer fungus concentrations in the 50–100 μL range, with a lower detection limit of 0.50 μL. The sensor electrode demonstrated high sensitivity, repeatability, and selectivity. The findings show that Cu- and Sn-codoped mesoporous BTGS is a viable alternative to costly electrode materials, such as gold and platinum, for amperometric sensor applications, demonstrating its applicability in the agricultural and food safety sectors.