Abstract
Surface-enhanced Raman scattering (SERS) enables the highly sensitive detection of (bio)chemical analytes in fluid samples; however, its application requires nanostructured gold/silver substrates, which presents a significant technical challenge. Here, we develop and apply a novel method for producing gold nanostructures for SERS application via the alternating current (AC) electrokinetic assembly of gold nanoparticles into two intricate and frequency-dependent structures: (1) nanowires, and (2) branched “nanotrees”, that create extended sensing surfaces. We find that the growth of these nanostructures depends strongly on the parameters of the applied AC electric field (frequency and voltage) and ionic composition, specifically the electrical conductivity of the fluid. We demonstrate the sensing capabilities of these gold nanostructures via the chemical detection of rhodamine 6G, a Raman dye, and thiram, a toxic pesticide. Finally, we demonstrate how these SERS-active nanostructures can also be used as a concentration amplification device that can electrokinetically attract and specifically capture an analyte (here, streptavidin) onto the detection site.
Highlights
There is a global need for more effective sensors to detectchemical molecules in fluid systems
It is well known that the motion and interactions of colloidal particles inside an alternating current (AC) electric field can be influenced by a suite of electrokinetic effects, including direct forces on constituent nanoparticles, as well as bulk electrohydrodynamic flows
A primary force involved in nanoparticle assembly is dielectrophoresis (DEP), which acts directly on induced dipoles in a non-uniform electric field [24]
Summary
There is a global need for more effective sensors to detect (bio)chemical molecules in fluid systems. A principal challenge in implementing SERS is in the fabrication of the nanostructured gold/silver surfaces required for the SERS activity Often, patterning these surfaces requires expensive and laborious techniques such as electron-beam lithography or focused ion beam milling [4]. We have published work involving a method for fabricating nanostructured silver surfaces via the electric field-driven assembly of silver nanoparticles from colloidal suspension [5]. These surfaces were applied for the sensitive detection of relevant chemical analytes [6,7]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
