Site-Specific SERS Assay for Survivin Protein Dimer: From Ensemble Experiments to Correlative Single-Particle Imaging

Small. 2017 Aug;13(32). doi: 10.1002/smll.201700802. Epub 2017 Jul 4.

Abstract

An assay for Survivin, a small dimeric protein which functions as modulator of apoptosis and cell division and serves as a promising diagnostic biomarker for different types of cancer, is presented. The assay is based on switching on surface-enhanced Raman scattering (SERS) upon incubation of the Survivin protein dimer with Raman reporter-labeled gold nanoparticles (AuNP). Site-specificity is achieved by complexation of nickel-chelated N-nitrilo-triacetic acid (Ni-NTA) anchors on the particle surface by multiple histidines (His6 -tag) attached to each C-terminus of the centrosymmetric protein dimer. Correlative single-particle analysis using light sheet laser microscopy enables the simultaneous observation of both elastic and inelastic light scattering from the same sample volume. Thereby, the SERS-inactive AuNP-protein monomers can be directly discriminated from the SERS-active AuNP-protein dimers/oligomers. This information, i.e. the percentage of SERS-active AuNP in colloidal suspension, is not accessible from conventional SERS experiments due to ensemble averaging. The presented correlative single-particle approach paves the way for quantitative site-specific SERS assays in which site-specific protein recognition by small chemical and in particular supramolecular ligands can be tested.

Keywords: SERS; correlative single-nanoparticle microscopy; dimer; elastic scattering; protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dimerization
  • Gold / chemistry
  • Humans
  • Metal Nanoparticles / chemistry
  • Microscopy, Electron, Scanning / methods
  • Spectrum Analysis, Raman / methods*
  • Survivin / analysis*
  • Survivin / chemistry

Substances

  • BIRC5 protein, human
  • Survivin
  • Gold