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Waveguide-based surface-enhanced Raman spectroscopy detection of protease activity using non-natural aromatic amino acids.

Nina TurkAli RazaPieter WuytensHans DemolMichiel Van DaeleChristophe DetavernierAndré G SkirtachKris GevaertRoel Baets
Published in: Biomedical optics express (2020)
Surface enhanced Raman spectroscopy (SERS) is a selective and sensitive technique, which allows for the detection of protease activity by monitoring the cleavage of peptide substrates. Commonly used free-space based SERS substrates, however, require the use of bulky and expensive instrumentation, limiting their use to laboratory environments. An integrated photonics approach aims to implement various free-space optical components to a reliable, mass-reproducible and cheap photonic chip. We here demonstrate integrated SERS detection of trypsin activity using a nanoplasmonic slot waveguide as a waveguide-based SERS substrate. Despite the continuously improving SERS performance of the waveguide-based SERS substrates, they currently still do not reach the SERS enhancements of free-space substrates. To mitigate this, we developed an improved peptide substrate in which we incorporated the non-natural aromatic amino acid 4-cyano-phenylalanine, which provides a high intrinsic SERS signal. The use of non-natural aromatics is expected to extend the possibilities for multiplexing measurements, where the activity of several proteases can be detected simultaneously.
Keyphrases
  • raman spectroscopy
  • amino acid
  • gold nanoparticles
  • sensitive detection
  • label free
  • loop mediated isothermal amplification
  • high throughput
  • high speed
  • circulating tumor cells
  • transcription factor