Plasmonic nanometal surface energy transfer-based dual excitation biosensing of pathogens

Abstract

In this assay, the simultaneous screening of foodborne bacterial pathogens, namely Escherichia coli and Salmonella typhimurium, was investigated by developing a highly specific dual-excitation biosensor which works based on plasmonic nanoparticle surface energy transfer (PSET) between aptamer capped plasmonic gold nanostructures (AuNSs) as capture probes and luminescent nanoparticles (LNPs) as signal probes labeled with complementary single-strand DNA of the utilized aptamers. For the characterization of the provided sensing probes, techniques such as UV-visible spectroscopy, dynamic light scattering, scanning electron microscopy, and circular dichroism spectroscopy were used. While CdSe/ZnS core/shell quantum dots (QDs) became excited with ultraviolet (UV) radiation at 350 nm, the light source utilized for excitation of NaYF₄:Yb,Er upconverting nanoparticles (UCNPs) was near-infrared (NIR) at 980 nm, and also the signal cross-talk possibility between QDs and UCNPs was removed using the dual-excitation technique. The limit of detection (LOD) was calculated to be as low as 7.38 and 9.31 CFU mL⁻¹ for simultaneous monitoring of E. coli and S. typhimurium in one experimental batch. The biosensor was also evaluated for detecting bacteria simultaneously in actual lake samples. The results proposed the viability of the technique for real-time sample analysis. Using numerous AuNSs and their corresponding UCNPs and QDs benefiting from distinct luminescence emission profiles, the suggested NSET-based biosensor may be utilized to simultaneously detect a wide range of analytes, posing good application prospects in various fields ranging from food safety analysis to biomedical applications.