Fabricating a Long-Range Ordered 3D Bimetallic Nanoassembly with Edge-On Substrate for Highly Sensitive SERS Sensing of Escherichia coli Bacteria

Long-range ordered three-dimensional (3D) nanoassembly of bimetallic nanorods has been fabricated on coffee ring formed on the silicon substrate. Two kinds of arrangements, i.e., axial alignment of the nanorods perpendicular and parallel to the substrate, can be observed in the nanoassembly. Moreover, facet blocking of the nanorods can efficiently yield 3D nanoassembly with edge-on substrate. The long-range ordered 3D nanoassembly with edge-on substrate can provide highly reproducible and significant Raman-enhanced signal in contrast with random aggregated substrate. The representative vibrational band of Escherichia coli bacteria could be efficiently amplified by aid of the substrate due to strong field enhancement effects arising from the superstructure. Furthermore, vancomycin-coated nanoassembly with edge-on substrate as a robust nanosensor can efficiently capture E. coli bacteria and improve stability of the nanosensor for assay of E. coli bacteria.