Label-free colorimetric aptasensor for highly sensitive and selective detection of proteins by using PNA/DNA hybrids and a cyanine dye

Abstract

Economical, fast and sensitive detection of proteins is essential to biomedical research as well as clinical diagnosis. Here, we demonstrated a label-free colorimetric aptasensor that uses PNA/DNA hybrids and a cyanine dye (DiSC₂(5)) for highly sensitive and selective detection of proteins in aqueous solution. This protocol, based on the difference in the binding interactions of DiSC₂(5) with PNA and the PNA/DNA hybrid causing different colors, can be applied for the detection of proteins. This sensing platform can specifically detect thrombin, our example analyte, with a detection limit of 0.4 nM. Moreover, the assay does not involve any chemical modification and enzyme amplification, and hence it is convenient, fast and low-cost. In principle, this approach can be used to detect proteins with specific aptamers by simply changing the sequences of the probe DNA for specific targets. Furthermore, this sensing platform provides a promising approach for the analysis of target proteins at point-of-care in resource-limited settings.