Bifunctional Nanozyme-Mediated Catalytic Signal Amplification and SERS for Ultrasensitive Detection of Pathogens in Milk Samples

According to a study published in the journal Analytical Chemistry, researchers at Wuhan Academy of Agricultural Sciences in China have developed a bifunctional gold-platinum (Au@Pt) core–shell nanozyme that can detect foodborne bacteria with high sensitivity (1). The nanozyme has catalytic properties and surface-enhanced Raman spectroscopy (SERS) activity that enables the detection of pathogens, including Salmonella typhimurium, in milk samples. The Au@Pt nomenclature indicates a core-shell nanoparticle where the core is made of gold (Au) and the shell is made of platinum (1).

Green Bacteria Colony | Image Credit: © zuki70 - stock.adobe.com

The bifunctional nanozyme is comprised of an ultrathin platinum shell of approximately 1 nm that catalyzes Raman-inactive molecules into Raman-active reporters, which amplifies the amount of signal molecules (1). Additionally, the researchers noted that the Au core functions as an active SERS substrate that enhances the signal of reporter molecules, further improving the detection sensitivity (1). Combining these properties, the researchers integrated the Au@Pt-based SERS platform with a magnetic immunoassay to construct a label-free SERS platform for highly sensitive detection of S. typhi, with a low detection limit of 10 CFU/mL (1).

The researchers also demonstrated that the bifunctional nanozyme-based SERS strategy is highly selective and can detect S. typhi in milk samples using a portable Raman spectrometer (1). The study presents a promising pathway for improving the sensitivity of label-free SERS detection of pathogens in various fields, including food safety and environmental analysis (1).

In summary, the team's findings have significant implications for public health and food safety, given that foodborne diseases affect millions of people worldwide every year (1). The new technique could provide an efficient way to detect pathogens and prevent their spread through contaminated food products. The authors suggest that future work could focus on further improving the sensitivity of the SERS platform and testing its ability to detect other pathogens (1).

Reference

(1) Li, Z.; Hu, J.; Zhan, Y.; Shao, Z.; Gao, M.; Yao, Q.; Li, Z.; Sun, S.; Wang, L.Coupling Bifunctional Nanozyme-Mediated Catalytic Signal Amplification and Label-Free SERS with Immunoassays for Ultrasensitive Detection of Pathogens in Milk Samples. Anal. Chem. 2023, ASAP. DOI: 10.1021/acs.analchem.3c00251