Highly Selective Colorimetric Detection of Cu2+Using EDTA- Complexed Chlorophyll-Copper/ZnO Nanorods with Cavities Specific to Cu2+as a Light-Activated Nanozyme

In this study, chlorophyll-copper (ChlCu)-modified ZnO nanorods (ChlCu/ZnO) were prepared, and then sodium ethylenediamine tetraacetate (EDTA) was used to remove part of Cu2+ in ChlCu, leaving cavities with specific adsorption activity for Cu2+ in E-ChlCu/ZnO. Appropriate EDTA treatment improved the photoactivity of ChlCu/ZnO and the adsorption selectivity to Cu2+. However, excessive EDTA treatment might lead to the collapse of the ChlCu structure, resulting in a decrease in photoactivity. The E-ChlCu/ZnO sample with 8 h of ChlCu treatment and 2 h of EDTA treatment showed optimal photoactivity. The as-prepared E-ChlCu/ZnO exhibited activity as a light-activated nanozyme, which could oxidize 3,3 ',5,5 '-tetramethylbenzidine (TMB) to blue under illumination, but when Cu2+ was present in the solution, this colorimetric reaction was inhibited; therefore, E-ChlCu/ZnO could be used for colorimetric detection of Cu2+. Because of the existence of specific cavities, E-ChlCu/ZnO showed excellent detection selectivity, a wide linear detection range (0-1 and 1-15 mu M), and a low detection limit (0.024 mu M) in the colorimetric detection of Cu2+.

Automated summary

In this study, ChlCu-modified ZnO nanorods were prepared and treated with EDTA to improve their photoactivity and adsorption selectivity to Cu2+. The optimal E-ChlCu/ZnO sample showed excellent colorimetric detection performance for Cu2+.