A Versatile Anisometric Metallic Supercrystal with Controllable Orientation on a Chip as a Stable and Reliable Label‐Free Biosensor

Abstract

Based on anisometric noble-metal nanocrystals, a universal fabrication protocol for preparing 3D supercrystals with controlled orientation on a chip has been developed. A comparison of the surface-enhanced Raman scattering (SERS) behavior of 3D nanorod supercrystals aligned vertically and parallel to the chip indicates that the SERS-enhancing ability and reproducibility of the former is superior to the latter. The 3D nanorod supercrystals aligned vertically to the chip have been utilized as highly sensitive SERS substrates for the label-free discrimination of Gram-positive and -negative bacteria. Furthermore, to strengthen the stability of the supercrystal substrate for assays of bacteria in biosamples, a coating of the antibiotic vancomycin can dramatically increase adhesion of bacteria on a nanointerface and simultaneously improve the SERS response of bacteria to achieve a layer-by-layer assembled, stable, and reliable biosensor for bacteria.

Bacteria Detection: From Powerful SERS to Its Advanced Compatible Techniques

“…This super crystal structure, which is arranged vertically on the chip, can be used as a highly sensitive SERS substrate to detect and recognize Gram-positive and Gram-negative bacteria without markers. [30] Jia et al fabricated a nano-assembly of Au@Ag nanorods, which is an excellent SERS active substrate. It is worth noting that this macro-ordered 3D assembled structure perpendicular to the substrate could act as a homogeneous and highly active SERS substrate for the identification and detection of bacteria.…”

“…This super crystal structure, which is arranged vertically on the chip, can be used as a highly sensitive SERS substrate to detect and recognize Gram‐positive and Gram‐negative bacteria without markers. [ 30 ] Jia et al. fabricated a nano‐assembly of Au@Ag nanorods, which is an excellent SERS active substrate.…”

“…It has been proven that an antibiotic vancomycin coating can significantly increase the adhesion of bacteria on nano‐interfaces and improve the SERS response of bacteria. [ 58 ] Wu et al. reported that the intrinsic SERS spectra of vancomycin‐coated Ag nanorods can be used to analyze 27 different strains from 12 bacterial species.…”