DOI: 10.5176/2251-2489_BioTech13.91
Authors: Gae Baik Kim, Jin Oh Lee, Young-Pil Kim
Abstract:
Proteases have been of significant interest because they are considered as one of promising biomarkers in association with cancer metastasis, inflammation and other degenerative diseases. Many attempts based on the optical sensing have been made to analyze the activity of proteases, but most of them require an expensive fluorescent readout and a laborintensive process. We demonstrate gold nanoparticle (AuNP)-based colorimetric assay which allows protease activity to be monitored in a simple and rapid way. The main principle is based on self-assembly of AuNPs through a coordination effect between carboxyl groups of AuNPs and hexahistidines at both ends of peptide substrates in the presence of divalent metal ions. Without multidentate ligands (e.g. nitrilotri-acetic acid), the anionic AuNPs were rapidly self-assembled and changed in color (from brown-reddish to violet) under the protease-free conditions, whereas the addition of protease did not cause the self-assembly of AuNPs due to cleavage of the peptide, thereby retaining the original color of the AuNPs. As a model system, we analyzed the protease (matrix metalloprotease-7) as a function of its concentrations. Depending on its peptide substrates, this result showed a good correlation between the self-assembly of AuNPs and protease activity. We anticipate that this strategy will find applications in activity-based analysis and relevant disease diagnosis of many other proteases in a high-throughput manner.
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