Double-functionalized gold nanoparticles with split aptamer for the detection of adenosine triphosphate

A newly designed functionalization type for gold nanoparticles (AuNP) with split aptamer has been developed for the detection of adenosine triphosphate (ATP). The ATP aptamer was split into two parts with their 5′ prime or 3′ prime modified with thiol. Both the 5′ SH and 3′ SH modified strands for each split aptamer fragment were functionalized onto the same AuNP to construct double-functionalized AuNP–DNA conjugates. Thus, the split aptamer can be reassembled into intact folded structure in the presence of ATP molecule with two potential assembly types, which induces the assembly of AuNP–DNA conjugates. In this double-functionalized system, the traditional assembly type might facilitate another assembly type, which was found to give much higher LSPR change in the presence of ATP than the traditional assembly type, and improve the sensitivity for ATP detection. Time courses of the assemble processes with different assembly types, Mg2+ concentrations, and aptamer fragments densities on AuNP were followed using the absorption ratio at 650 nm and 520 nm. ATP response with this newly designed system was investigated using absorption spectra and dynamic light scattering method.