Cu (II)-based metal-organic xerogels as a novel nanozyme for colorimetric detection of dopamine

Cu (II)-based metal-organic gels (Cu-MOGs), which are formed by 4-[2,2′:6′,2″-terpyridine]-4′-ylbenzoic acid (Hcptpy) and Cu (II) through ionic interactions, π-π stacking, van der Waals and hydrogen bonding , have been simply synthesized and used for the preparation of Cu (II)-based metal-organic xerogels (Cu-MOXs). Owing to the metal active sites in Cu-MOXs, Cu-MOXs were successfully applied to chromogenic experiment. The peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB), which could be catalyzed by Cu-MOXs from TMB to the oxidation state of TMB (oxTMB) and the color of TMB could be changed from colorless to blue with maximum absorbance at 657 nm, was selected as chromogenic agent. Thus, the Cu-MOXs-TMB-H 2 O 2 system based on MOXs was established. Due to the inhibitory effect of dopamine (DA) on oxidation process of TMB, the characteristic absorption peak intensity of oxTMB decreased when the DA was added into the mixed solution. Subsequently, the Cu-MOXs-TMB- H 2 O 2 system was used for DA detection. The linear range for DA was 0.5 μM–20 μM and the detection limit was 85.76 nM. Our work has helped to develop the promising application of Cu-MOGs material in the field of nanozymes property.