In Vitro Selection of DNA Aptamers for a Small-Molecule Porphyrin by Gold Nanoparticle-Based SELEX.

In this study, a new strategy for the selection of aptamers against small-molecule target was established using gold nanoparticles (AuNPs) as the separation matrix and Zinc(II)-Protoporphyrin IX (ZnPPIX) as the target molecule without the immobilization step due to the absorption of ssDNA on AuNPs. The progress of the selection process was monitored by the recovery rate and the fluorescence enhancement of N-methyl mesoporphyrin IX (NMM) after reacting with each selected pool. After 11 rounds of selection, a truncated aptamer ZnP1.2 with a low-micromolar dissociation constant was obtained, and it also showed good fluorescence enhancement for NMM and the enhanced peroxidase activity after binding with hemin, indicating this functional aptamer has potential to be a light-up fluorescent probe and a DNAzyme which could be used as an alternative to peroxidases for many colorimetric or chemiluminescent detections in biosensing events. The experimental results show that the simple and convenient AuNP-based SELEX is very conducive to the selection of aptamers for small-molecule targets.