T2.3 Bright and Stable SERS Nanoparticle Tags with Locked Hydrophobic Inner Domains
Ruiyang Xue (University of Illinois at
Urbana-Champaign),
Li Lin (University of Illinois at Urbana-Champaign), Lucas Lane (Nanjing
University),
Subhendu Pandit (University of Illinois at Urbana-Champaign),
Shuming Nie (University of Illinois at Urbana-Champaign)
Surface enhance Raman scattering (SERS) is an ultra-sensitive spectroscopic technique induced by surface plasmon resonance effect on metal surface. It greatly boosts the intensity of standard Raman signal of molecules and thus exhibits great potential in the fields such as nanomaterials science, optical devices for single-molecule sensing and trace analysis. Specially, SERS nanoparticles (NPs), which are plasmonic metallic colloids modified with Raman reporter molecules and surface coatings, has been a promising optical tag in biomedical applications. High brightness and stability are of great significance for SERS NPs to achieve satisfactory detection sensitivity.
In this work, a wet-chemistry method is reported to synthesize SERS NPs with enhanced intensities and better signal stability by introducing a hydrophobic aliphatic domain into polyethylene glycol (PEG) coating. The aliphatic domain is composed of an 11-carbon alkyl chain, which forms a hydrocarbon environment near Au surface, leading to a change in the refractive index and dielectric constant of the ambient medium to increases NP polarizability. An additional 2 to 5 times SERS enhancement is introduced by this hydrophobic enhancement effect, which turns out to be universal for a variety of Raman reporter molecules. We also demonstrate that larger packing density and longer aliphatic chain length tends to bring in higher Raman enhancement. Moreover, the hydrophobic shell around NPs protects Raman molecules from diffusing out via favorable hydrophobic and van der Waals interactions, resulting in a better long-term signal stability in different solvents. Given that a hypothetic competitive adsorption between reporters and hydrophobic domain modified PEGs, a tradeoff strategy has been put forward to adjust their relative concentrations, achieving an optimal SERS intensity for specialized applications. Our investigation into hydrophobic domain enhanced gold SERS nanoparticles provides a new strategy for Raman signal amplification and open up new opportunities for SERS-based optical devices and biomedical applications.
Event Timeslots (1)
SYMPOSIUM T2 – MATERIALS PROCESSING AND CHEMISTRY
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Ruiyang Xue
Location: Technological Institute M177