Enzymatically driven formation of palindromic DNA-Au nanoparticles for snowball assembly and colorimetric biosensing

Abstract

A strategy for enzymatically driven formation of palindromic DNA-Au nanoparticles (AuNPs) was designed via specific recycling recognition and release of target DNA to/from hairpin DNA functionalized AuNPs (DNA-AuNPs), which led to the snowball assembly of palindromic DNA-AuNPs at single temperature. The assembly was demonstrated with UV–vis spectra, TEM images, dynamic light scattering and PAGE analyses, and could be monitored by substantial red shift of the adsorption peak and the colour change of DNA-AuNPs from red to pink and ultimately slight purple, leading to a convenient method for colorimetric detection of target DNA. By combining with AuNPs-catalyzed silver enhancement, sensitive and selective scanometric assay was further achieved. This strategy could be extended to a wide range of analytes by coupling with other strategies releasing tag DNA from a DNA duplex upon the recognition of target analyte for enzymatically driven formation and snowball assembly of palindromic DNA-nanoparticles. As a proof-of-concept, the extended methods for thrombin detection showed excellent biosensing performance, indicating universal applicability of the proposed strategy for colorimetric biosensing of both DNA and proteins.