Transition metal ion-coordinated porous organic polymer to enhance the peroxidase mimic activity for detection of ascorbic acid and dopamine

Abstract

Porous organic polymers (POPs) have been fabricated with intriguing physicochemical properties, which can be used in a wide range of emerging applications. However, they show less activity in nanozymes. Attempts have been made to boost nanozyme activity with incorporation of nanoparticles into POPs. The importance of M²⁺ incorporation has been highlighted, which prevents leaching and agglomeration. In this study, we prepared transition metal ion-coordinated porous organic polymers (Cu²⁺@POP, Ni²⁺@POP and Co²⁺@POP) by a mechanochemical method. As-prepared Cu²⁺@POP, Ni²⁺@POP and Co²⁺@POP exhibited excellent 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation reaction in the presence of H₂O₂. The oxidation reaction occurred by single electron transfer, to convert colorless TMB to blue colored ox-TMB. Furthermore, the peroxidase like activity of Cu²⁺@POP has been shown to potentially prevent TMB oxidation in the presence of ascorbic acid (AA) and dopamine (DA). Based on the inhibition effect, we achieved low detection limits of 1.4 mM and 1 mM for AA and DA through colorimetric method. To the best of our knowledge, for the first time we investigate colorimetric-based detection of both AA and DA. With these findings, Cu²⁺@POP has excellent catalytic activity, providing a promising prospect for biosensors and clinical fields.