Novel Au–SiO2–WO3 Core–Shell Composite Nanoparticles for Surface-Enhanced Raman Spectroscopy with Potential Application in Cancer Cell Imaging

Abstract

With the rapid development of nanotechnology during the last decades, the ability to detect and control individual objects at the nanoscale has enabled to deal with complex biomedical challenges. In cancer imaging, novel nanoparticles (NPs) offer promising potential to identify single cancer cells and precisely label larger areas of cancer tissues. Herein, a new class of size tunable core-shell composite (Au-SiO2-WO3) nanoparticles is reported. These nanoparticles display an easily improvable ∼ 103 surface-enhanced Raman scattering (SERS) enhancement factor (EF) with a double Au shell for dried samples over Si wafers and several orders of magnitude for liquid samples. WO3 core nanoparticles of 20-50 nm in diameter are sheathed by an intermediate 10-60 nm silica layer, produced by following the Stöber basedprocess and Turkevich method, followed by a 5-20 nm thick Au outer shell. By attaching 4- mercaptobenzoic acid (4-MBA) molecules as Raman reporters to the Au, high-resolution Raman maps which pinpoint the nanoparticles’ location are obtained. Our preliminary results confirm their advantageous SERS properties for single-molecule detection, significant cell viability after 24 h and in vitro cell imaging using coherent anti-stokes Raman scattering (CARS). Our long-term objective is to measure SERS nanoparticles in vivo using NearInfrared light.