Reconfigurable surface enhanced Raman spectroscopy device and method therefor

#This invention relates to surface enhanced Raman spectroscopy (SERS). More specifically, this invention relates to a highly sensitive SERS device that is simple and cost effective to produce, and re-usable.

#There is a pronounced global need for more sensitive and cost-effective devices to detect trace amounts of biochemical, particularly disease-causing, analytes in environmental or biological fluids. Additionally, the ability to detect biomarkers of diseases such as cancer at low levels in the early stages will allow for rapid and guided treatment, with ultimately better patient outcomes. Current detection methods, such as polymerase chain reaction (PCR), enzyme-linked immunosorbant assay (ELISA), or mass spectrometry (MS), require expensive reagents, trained personnel, and dedicated laboratory facilities for accurate and sensitive detection. Recently, Raman spectroscopy, and particularly the added sensitivity imparted by surface enhanced Raman spectroscopy (SERS), have shown promise for the sensitive detection of biomolecules, chemical contaminants, illicit drugs, and whole cells.

#SERS provides a wealth of highly resolved and chemically specific vibrational information, at intensities up to 14 orders of magnitude greater than those of normal Raman spectroscopy, and through combination with fiber optics, diode lasers, and portable Raman spectrometers, represents a promising technique for point-of-care diagnostics or remote detection. SERS occurs through two mechanisms: (1) an electromagnetic enhancement, resulting from localized surface plasmon resonances—electromagnetic excitations which are confined within nanostructured metallic surfaces, and act to locally enhance both the incident electromagnetic field and the scattered Raman field; and (2) a chemical enhancement, resulting from charge transfer between the metal and the adsorbed analyte. SERS is often performed in colloidal solutions of suspended nanoparticles; however, this method of detection suffers from poor reproducibility, inhomogeneous nanoparticle/analyte distributions, and a transiency of SERS active sites. Therefore, a precisely fabricated, well-structured, nanosubstrate is key to good SERS detection. Current methods of nanofabrication are expensive and time-consuming, requiring dedicated clean room facilities, as well as involved techniques such as focused ion beam etching, electron beam lithography, atomic layer deposition, or metal film over nanosphere deposition. Unfortunately, the costs and specific requirements limit the wide-spread use of SERS.

#For a greater understanding of the invention, and to show more clearly how it may be carried into effect, embodiments will be described, by way of example, with reference to the accompanying drawings, wherein:

#FIG. 1 is a schematic representation of (a) preparation of a nanoparticle structure on microelectrodes of a SERS device, (b)-(c) use of the SERS device to detect an analyte, and (d) removal of the nanoparticle structure so that the microelectrodes may be reused, according to one embodiment.

#FIGS. 2A-2H are images of SERS devices according to various embodiments, wherein FIGS. 2A and 2C are photomicrographs of AgNP structures produced on microelectrodes through electrokinetic deposition, and FIGS. 2B and 2D are corresponding SEM images of the nanostructures; FIG. 2E is a photomicrograph of AgNP structures produced on microelectrodes through electrokinetic deposition by applying a DC offset, and FIG. 2F is a SEM image of the nanostructures; FIG. 2G is a photomicrograph of microelectrodes with electrokinetic deposition of AuNPs, and FIG. 2H is a SEM image of the AuNPs.

#Described herein are SERS devices that are inexpensive, robust, and portable. Additionally, a SERS device as described herein may be reusable. Also described herein are methods for using and preparing the SERS devices with simple, rapid, and inexpensive fabrication techniques.

#As used herein, the term “SERS device” refers to a device that may be used to analyze an analyte using Raman spectroscopy, comprising a solid substrate, two or more microelectrodes disposed on the substrate, and nanoparticles disposed on the structure such that the nanoparticles form a nanoparticle structure between the two or more microelectrodes according to an electric field between the microelectrodes.

#As used herein, the term “solid substrate” refers to a support material for a SERS device, on which the two or more microelectrodes are disposed. The solid substrate is robust, meaning that it has one or more characteristics such as: self-supporting, resists bending, washable, and waterproof. Although the solid substrate resists bending (e.g., it does not bend in the absence of applied force), it may be flexible. The solid substrate is not electrically conductive, and may comprise one or more materials such as, for example, silicon, glass, quartz, alumina, polymer, paper.