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Issue 6, 2015
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A sensitive assay for trypsin using poly(thymine)-templated copper nanoparticles as fluorescent probes

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Abstract

A new, simple and sensitive fluorescence strategy was developed for the trypsin assay based on copper nanoparticles (CuNPs) and its different fluorescence response toward trypsin-catalyzed hydrolysis of cytochrome c (Cyt c). Polythymine (poly T)-templated CuNPs served as effective fluorescent probes. Cyt c is well-known to act as a quencher. However, herein, a low concentration of Cyt c was designed specially to act as the substrate of trypsin to avoid the quenching effects by electron transfer from Cyt c to CuNPs. In the presence of trypsin, Cyt c hydrolyzes to small peptides, releasing free cysteine residues. Nonfluorescent coordination complexes were formed upon exposure to free cysteine residues by a metal–ligand bond between Cu atoms and sulfur atoms, leading to a decreased fluorescence response to CuNPs. This novel method for the quantitative determination of trypsin has a linear detection range from 0.25 μg mL−1 to 1000 μg mL−1 and a relatively low detection limit of 42 ng mL−1. To the best of our knowledge, this is the first application of the trypsin-catalyzed hydrolysis reaction of Cyt c to produce quenching effect in bioanalysis, which provided a novel approach for the biochemical sensing strategy.

Graphical abstract: A sensitive assay for trypsin using poly(thymine)-templated copper nanoparticles as fluorescent probes

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Article information


Submitted
04 Nov 2014
Accepted
05 Dec 2014
First published
05 Dec 2014

Analyst, 2015,140, 1871-1875
Article type
Paper
Author version available

A sensitive assay for trypsin using poly(thymine)-templated copper nanoparticles as fluorescent probes

L. Ou, X. Li, L. Li, H. Liu, A. Sun and K. Liu, Analyst, 2015, 140, 1871
DOI: 10.1039/C4AN01994F

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