A Protocol for Gold Nanoparticle-Assisted Aptamer Selection for a Small Molecule Porphyrin to Develop DNAzyme

DNAzymes can be obtained by in vitro selection, when specific analytes such as porphyrins are used as targets. In this process, the immobilization of targets serving as a major step is not suitable for the selection of DNAzymes because small molecules like porphyrins lack active groups for immobilization. Here, we develop a gold nanoparticle (AuNPs)-assisted aptamer selection for the small molecule porphyrin Zinc(II)-Protoporphyrin IX (ZnPPIX), which can realize the selection of DNAzyme without an immobilization step, and the detailed in vitro selection process in solution is described.