Citric Acid-Tailored Cadmium Germanate Nanoparticles: A Real-Time Sensing Platform for Listeria Monocytogenes Monitoring

The foodborne pathogen Listeria monocytogenes poses a severe threat to public health due to its high virulence and environmental adaptability, necessitating the development of sensing technologies for real-time monitoring of early contamination. This investigation addresses the detection bottleneck of its specific metabolic marker, acetoin, by innovatively developing a citric acid-assisted sol-gel method that successfully synthesizes Cd₂GeO₄ nanoparticles. This approach overcomes the critical challenge of controlling the nanostructure and surface defect states of Ge-based materials, which is often problematic with traditional high-temperature solid-state or hydrothermal methods. The experiments demonstrate that the Cd₂GeO₄ sensor exhibits outstanding performance for acetoin. DFT calculations elucidated that the Cd-O sites on the (110) crystal plane achieve specific recognition through the chemisorption of the C=O and OH groups of acetoin. These insights elucidate the mechanism behind acetoin sensing, suggesting that Cd₂GeO₄ may be employed as a novel sensing material for Listeria monocytogenes detection.