Authors:	N. Turk, A. Raza, P.C. Wuytens, H. Demol, M. van Daele, C. Detavernier, A. Skirtach, K. Gevaert, R. Baets
Title:	Waveguide-based surface-enhanced Raman spectroscopy detection of protease activity using non-natural aromatic amino acids
Format:	International Journal
Publication date:	8/2020
Journal/Conference/Book:	Biomedical Optics Express
Volume(Issue):	11(8) p.4800-4816
DOI:	10.1364/BOE.398038
Citations:	12 (Dimensions.ai - last update: 17/11/2024) 7 (OpenCitations - last update: 27/6/2024) Look up on Google Scholar
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Abstract

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.