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Proc Natl Acad Sci U S A. 2006 Mar 14;103(11):3978-82. Epub 2006 Mar 1.

Gold nanoparticles-based protease assay.

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  • 1Department of Chemical Sciences and Institute for Membrane Technology-National Research Council, Padova Section, University of Padova, Via Marzolo 1, 35131 Padova, Italy.


We describe here a simple assay that allows the visual detection of a protease. The method takes advantage of the high molar absorptivity of the plasmon band of gold colloids and is based on the color change of their solution when treated with dithiols. We used C- and N-terminal cysteinyl derivatives of a peptide substrate exploiting its selective recognition and cleavage by a specific protease. Contrary to the native ones, cleaved peptides are unable to induce nanoparticles aggregation; hence, the color of the solution does not change. The detection of two proteases is reported: thrombin (involved in blood coagulation and thrombosis) and lethal factor (an enzyme component of the toxin produced by Bacillus anthracis). The sensitivity of this nanoparticle-based assay is in the low nanomolar range.

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