Improving SERS detection using Membrane Encapsulated Noble Metal Nanostructures

Abstract

Precise control over the size, shape, and local environment of nanoparticles is vital for the development of new technologies based on these materials and their novel properties. This is especially important in understanding how these size-dependent properties impact the detection of biological and chemical targets. This work focuses on the synthesis and modification of gold coated silver nanoparticles (Ag@Au) for enhancing and facilitating the detection of drug molecules. We will reveal that these solution-phase Ag@Au nanoparticle cores can be entrapped in porous silica cages through novel nanoparticle engineering. Silica shells offer robust protection of the metal nanoparticles against aggregation thereby preserving their novel optical properties; however, this shell prevents direct interaction between the metal core and analytes limiting applications in surface-enhanced Raman scattering (SERS). By removing the innermost layer of the silica shell, we have engineered optically stable Ag@Au nanoparticles that are protected by silica membranes which can be used to screen analytes using both localized surface plasmon resonance spectroscopy and SERS. Detection of both biologically-relevant drug molecules will be discussed.