A peptide with a cysteine terminus: probe for label-free fluorescent detection of thrombin activity

Abstract

Thrombin has been implicated in atherosclerotic disease development. However, thrombin activity detection is currently limited because of the lack of convenient fluorescent probes. We developed a label-free fluorescent method to assay thrombin activity on the basis of a designed peptide probe with a thrombin-cleavable peptide sequence and a cysteine terminus. The peptide probe can be conjugated to DNA-templated silver nanoclusters (DNA-AgNCs) through Ag-S bonding; as a result, the fluorescence of DNA-AgNCs was enhanced. As the DNA-AgNCs-peptide conjugate was adsorbed to graphene oxide (GO), the enhanced fluorescence of DNA-AgNCs was quenched. Once the peptide probe was cleaved by thrombin, the resulting release of the DNA-AgNCs from the surface of GO restored the enhanced fluorescence. Thrombin can be determined with a linear range of 0.0-50.0 nM with a detection limit of 1 nM. The thrombin-sensitive probe with a cysteine terminus may be developed into probes to detect other proteases.

An aptasensor for the label-free detection of thrombin based on turn-on fluorescent DNA-templated Cu/Ag nanoclusters

“…The limit of detection (LOD) is as low as 1.6 nM. As shown in ESI Table S2, † the lowest LOD is 30 pM for other methods, 9,10,[50][51][52][53] wherein the detection is carried out using exonuclease Iassisted target recycling and SYBR Green I-aided signal ampli-cation, 9 while the other method with the LOD of 31.3 pM is based on the dye-labeled aptamer-assembled graphene. 10 These methods improve the sensitivity; however, SYBR Green I is a toxic organic dye while labeling an aptamer is expensive and time consuming.…”

A new fluorescence method for detection of famotidine based on polyethyleneimine‐templated Ag nanoclusters

“…[ 5 ] Among them, silver (Ag ) NCs have gathered wide research interest over the past decade. To date, Ag NCs of different luminescence colours have been prepared using various stabilizing agents or templates such as proteins, [ 6 ] polypeptide, [ 7 ] nucleotides, [ 8 ] polymers, [ 9 ] and have been widely used in chemical sensing, [ 10–12 ] as biomarkers, [ 13,14 ] in disease diagnosis, [ 15 ] pesticide residues detection, [ 16 ] and drug molecule [ 17 ] detection.…”