Microspectroscopic SERS detection of interleukin-6 with rationally designed gold/silver nanoshells

Yuling Wang, Mohammad Salehi, Max Schütz, Katharina Rudi, Sebastian Schlücker*

*Corresponding author for this work

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Rationally designed gold/silver nanoshells (Au/Ag-NS) with plasmon resonances optimized for red laser excitation in order to minimize autofluorescence from clinical samples exhibit scattering cross-sections, which are ca. one order of magnitude larger compared with solid quasi-spherical gold nanoparticles (Au-NPs) of the same size. Hydrophilic stabilization and sterical accessibility for subsequent bioconjugation of Au/Ag-NS is achieved by coating their surface with a self-assembled monolayer (SAM) of rationally designed Raman reporter molecules comprising terminal mono- and tri-ethylene glycol (EG) spacers, respectively. The stability of the hydrophilically stabilized metal colloid was tested under different conditions. In contrast to metal colloids coated with a SAM without terminal EG spacers, the hydrophilically stabilized SERS particles do not aggregate under physiologically relevant conditions, i.e., buffer solutions with high ionic strength. Using these rationally designed SERS particles in conjunction with a microspectroscopic acquisition scheme, a sandwich immunoassay for the sensitive detection of interleukin-6 (IL-6) was developed. Several control experiments demonstrate the high specificity of the assay towards IL-6, with a lowest detectable concentration of ca. 1 pg mL -1. The signal strength of the Au/Ag-NS is at least one order of magnitude higher compared with hydrophilically stabilized, non-aggregated solid quasi-spherical Au-NPs of the same size.

Original languageEnglish
Pages (from-to)1764-1771
Number of pages8
JournalAnalyst
Volume138
Issue number6
DOIs
Publication statusPublished - 21 Mar 2013
Externally publishedYes

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