Porphyrin metalation catalyzed by DNAzymes and nanozymes

Abstract

Metalloporphyrins play important roles in biology, such as magnesium porphyrin for photosynthesis and iron porphyrin for carrying and transferring oxygen. They are also powerful molecules for the development of biosensors, phototherapy, photocatalysis, photodegradation, light harvesting, and water splitting. However, the porphyrin metalation reaction is difficult to achieve at room temperature due to a high kinetic barrier. Inspired by the pioneering work in catalytic antibodies, ribozymes, DNAzymes and nanozymes have been developed as enzyme mimics to accelerate this reaction. This review summarizes the progress in DNAzymes and nanozymes due to their excellent stability and low cost. We first introduce the structure and property of common porphyrins and metalloporphyrins. DNAzymes for porphyrin metalation are then reviewed, including early work, recent work using Pb²⁺ as a cofactor, and non-G-quadruplex DNAzymes. The catalytic mechanisms of DNAzymes are also discussed, especially the role of metal ions. Subsequently, nanozymes for porphyrin metalation based on graphene and a few other nanomaterials are reviewed. In this part, the interactions between the nanozymes and porphyrins are elucidated to describe the catalytic effect. In addition, beta-cyclodextrin and some surfactants that can form micelles in water were also found to have catalytic activity. Finally, we review the applications of porphyrin metalation reactions for the detection of various metal ions, improving photocatalytic activity, and removing heavy metal ions in water.