The mechanism of an enzymatic reaction-induced SERS transformation for the study of enzyme-molecule interfacial interactions

Phys Chem Chem Phys. 2016 Nov 23;18(46):31787-31795. doi: 10.1039/c6cp05978c.

Abstract

We report the observation of a novel effect in which the vibrational frequencies and spectral intensity of enzyme (E)-conjugated surface-enhanced Raman scattering (SERS)-active reporter molecules (4-mercaptobenzoic acid (4-MBA)) shift and change regularly as a function of the concentration of the substrate molecule (S). We attribute the frequency shifts and intensity changes in the E-reporter complex to the binding of S to the active site of E, which affects the electronic structure, polarizability and electron density of the molecule. Our observations demonstrate the creation of an E-conjugated SERS-active reporter complex as a SERS-active nano-mechanical sensor for bio-detection. Specifically, we used glucose oxidase (GOx), which was capable of achieving detection sensitivity comparable to that of a conventional sandwich enzymatic reaction. Furthermore, 2D correlation SERS spectroscopy was performed to better investigate the glucose-responsive mechanism, and the results of these experiments support our proposed conclusion. These findings pave a new pathway for utilizing the specific response to glucose via the SERS method, which can achieve a detection limit of 10-6 mol L-1 for glucose and cover a much wider concentration range, including the blood glucose concentrations in healthy (3-8 mmol L-1) and diabetic (9-40 mmol L-1) individuals, than the current chromogenic assays.

MeSH terms

  • Benzoates / chemistry
  • Biosensing Techniques / methods
  • Blood Glucose / analysis
  • Catalytic Domain
  • Gluconates / chemistry
  • Glucose / chemistry*
  • Glucose Oxidase / chemistry*
  • Metal Nanoparticles / chemistry
  • Models, Chemical
  • Protein Binding
  • Silver / chemistry
  • Spectrum Analysis, Raman
  • Sulfhydryl Compounds / chemistry

Substances

  • Benzoates
  • Blood Glucose
  • Gluconates
  • Sulfhydryl Compounds
  • 4-mercaptobenzoate
  • Silver
  • Glucose Oxidase
  • Glucose
  • gluconic acid