One-step competitive assay for detection of thrombin via disassembly of diblock oligonucleotide functionalised nanogold aggregates

In this study, we developed a simple, sensitive and cost effective sensing strategy for thrombin. Two polyadenine diblock oligonucleotides, one containing a thrombin aptamer (TA) and the other one a partial complementary sequence to thrombin aptamer (TAC), were designed to anchor on gold nanoparticle (AuNP) surface. The hybridisation of these two DNA strands promoted the assembly of some AuNPs together and formed AuNP ag-gregates. The introduction of thrombin competitively bound to its aptamer and triggered the disassembly of AuNP aggregates. The change in plasmon absorption of AuNPs generated significant signal without requiring labeling or preprocessing steps. This simple one-step competitive assay had been demonstrated for the detection of thrombin with a detection limit of 0.81 pM and a dynamic range from 10 pM to 10 nM. Furthermore, this method was successfully demonstrated to perform analysis in 10-fold diluted serum solutions without sophis-ticated instruments. This sensitive and convenient strategy is expected to provide a prospective alternative in clinical application in a fast and straight forward manner.

Automated summary

In this study, a simple, sensitive, and cost-effective sensing strategy for thrombin was developed. The strategy involved the use of polyadenine diblock oligonucleotides anchored on gold nanoparticles (AuNPs) to detect thrombin. Binding of thrombin to its aptamer triggered the disassembly of AuNP aggregates, resulting in a significant signal change. The assay demonstrated a detection limit of 0.81 pM and a dynamic range from 10 pM to 10 nM, and could be performed in diluted serum solutions without sophisticated instruments.