Quantitative Detection of Trypsin Activity via Surface Enhanced Raman Scattering
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Protease activities provide essential physiological functions in the human body, such as food absorption, and abnormal protease activities can lead to severe diseases. In order to diagnose and monitor these diseases, it is urgent and desirable to develop quantitative detection methods of proteolysis. Currently, the surface-enhanced Raman scattering (SERS) technique has received much attention due to its multiplexed analysis and signal enhancement. However, SERS quantitative analysis remains a challenge because of variable SERS enhancements. To overcome this barrier, we introduced an internal standard to minimize the signal variations. In this thesis, silver nanocubes (AgNCs) were used as SERS substrates. The short peptide (sequence CQSARW) was used to monitor the proteolysis of trypsin. Peptides and internal standards were chemisorbed on AgNC surfaces via metal-thiolate bonding. After Raman measurements, the degree of digestion was determined by comparing the normalized spectra of the peptide before and after trypsin digestion. To demonstrate the application of this technology in drug discovery, we evaluated the inhibition capability (IC50) of two known trypsin inhibitors, Ovomucoid and Bowman-Birk inhibitor (BBI). It was found that the measured IC50 values of the trypsin inhibitors are at the same orders of magnitude as the literature values.
Lee, Chin-An (2018). Quantitative Detection of Trypsin Activity via Surface Enhanced Raman Scattering. Master's thesis, Texas A & M University. Available electronically from