A highly sensitive SERS sensor for malachite green detection based on spiky Fe₃O₄@Au supraparticles

A novel label-free analytical strategy based on surface-enhanced Raman spectroscopy (SERS) has been developed for the detection of malachite green (MG) using spiky Fe₃O₄@Au supraparticles (Fe₃O₄@AuSPs). These supraparticles function dually as both concentrating probes and SERS-active substrates, leveraging the "built-in hotspots" at the tips of the spiky gold nanostructures and the magnetic aggregation effect of the core to achieve dual-signal amplification. Upon interaction with MG, the Fe₃O₄@AuSPs specifically capture the target analyte and exhibit strong SERS enhancement. Under the optimized conditions, the method achieved a limit of detection (LOD) as low as 10^-12 M, with a linear range spanning from 10^-4 to 10^-11 M. It also demonstrated high specificity and was successfully applied to detect MG in real samples, including water from aquaculture systems and biological samples (fish, prawns, and crabs). This work provides a practical and efficient approach for MG monitoring in aquatic products, significantly reducing both detection time and cost, and exhibits strong potential for application in food safety surveillance.