Core-shell nanorod columnar array combined with gold nanoplate-nanosphere assemblies enable powerful in-situ SERS detection of bacteria.

Development of a label-free ultrasensitive nanosensor for detection of bacteria is presented. Sensitive assay for Gram-positive bacteria was achieved via electrostatic attraction-guided plasmonic bifacial superstructure/bacteria/columnar array assembled in one step. Dynamic optical hot-spots were formed in the hybridized nanoassembly under wet-dry critical state amplifying efficiently the weak vibrational modes of three representative food-borne Gram-positive bacteria, i.e., Staphylococcus xylosus, Listeria monocytogenes and Enterococcus faecium. These three bacteria with highly-analogous Raman spectra can be effectively differentiated through droplet wet-dry critical SERS approach combined with 3D PCA statistical analysis so that highly sensitive discrimination of bacterial species and samples containing mixtures of bacteria can be achieved.