Using G-Rich Sequence to Enhance the Peroxidase-Mimicking Activity of DNA-Cu/Ag Nanoclusters for Rapid Colorimetric Detection of Hydrogen Peroxide and Glucose

Four kinds of DNA-based Ag and Cu/Ag nanoclusters (NCs) were synthesized and their fluorescence properties were investigated at pH 7.0 and 5.5. Among them the Cu/Ag NCs templated by DNA containing both C-rich and G-rich sequences (the c-myc TBA-Cu/Ag NCs) give the strongest and the most stable fluorescence emission at similar to 555 nm under neutral and acidic conditions. Unexpectedly, the c-myc TBA-Cu/Ag NCs can catalyze efficiently and rapidly the reaction of hydrogen peroxide (H2O2) with 3,3 ',5,5 '-tetramethylbenzidine (TMB) to produce blue TMB oxide (TMBox) under acidic conditions, indicating the high peroxidase-mimicking activity. Based on this nanozyme the detection for H2O2 and glucose was performed using colorimetric method. The results indicate that the linear range of detection for H2O2 is from 0.1 to 1 mM with the detection limit (LOD) of 7.42 mu M, while the linear range is from 0.1 to 0.7 mM and LOD was calculated to be 9.38 mu M for glucose. Additionally, glucose can be successfully detected in diluted serum samples and has an acceptable recovery rate, indicating that this nanozyme has a potential application prospect.