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Title: A sensitive assay for trypsin using poly(thymine)-templated copper nanoparticles as fluorescent probes. Author: Ou LJ, Li XY, Li LJ, Liu HW, Sun AM, Liu KJ. Journal: Analyst; 2015 Mar 21; 140(6):1871-5. PubMed ID: 25657995. 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.[Abstract] [Full Text] [Related] [New Search]