ABSTRACT
Regulating the catalytic activity of nanozymes is significant for their applications in various fields.Here,we demonstrate a new strategy to achieve reversible regulation of the nanozyme's activity for sensing purpose.This strategy involves the use of zero-dimensional M0S2 quantum dots(MQDs)as the building blocks of nanozymes which display very weak peroxidase(POD)-like activity.Interestingly,such POD-like activity of the MQDs largely enhances in the presence of Fe3+while diminishes with the addition of captopril thereafter.Further investigations identify the mechanism of Fe3+-mediated aggregation-induced enhancement of the POD-like activity and the inhibitory effect of captopril on the enhance-ment,which is highly dependent on their concentrations.Based on this finding,a colorimetric method for the detection of captopril is developed.This sensing approach exhibits the merits of simplicity,rapidness,reliability,and low cost,which has been successfully applied in quality control of captopril in pharmaceutical products.Moreover,the present sensing platform allows smartphone read-out,which has promising applications in point-of-care testing devices for clinical diagnosis and drug analysis.
ABSTRACT
Objective To establish a simple and convenient method and study the feasibility of using gold nanoparticle composites (ssDNA-AuNPs) for colorimetric detection of gamma radiation.Methods The composites ssDNA-AuNPs were prepared by applying the ssDNA to the surface of AuNPs,and then were irradiated with gamma ray with absorbed doses of 0,5,10,20,and 30 Gy,respectively.Subsequently the color change in the solutions were observed simultaneously with absorption spectra being measured.The linear relationship between the ratio of A625/A521 in the absorption spectrum and the absorbed dose was established.Results With the increase of radiation dose,the color of the solutions changed from wine-red to blue-violet gradually,the ratio of A625/A521 in absorption spectra had excellent liner response for absorbed dose ranging from 0 to 30 Gy,and the linear equation was A625/A521 =0.020 6 + 0.303 6 E(R2 =0.991 5).Conclusions The ssDNA-AuNPs synthesized in this experiment can be successfully used for colorimetric detection of gamma absorbed dose,and a simple and convenient method for detection of gamma radiation has been newly established.
ABSTRACT
A sensitive colorimetric method for the detection of copper ions (Cu2+) was developed based on the surface modification of silver/platinum nanoclusters (Ag/Pt NCs) and regulation of peroxidase-like activity. It was found that 3-mercaptopropionic acid (MPA) could inhibit the catalytic ability of Ag/Pt NCs; however, it lost the inhibition toward catalytic ability of Ag/Pt NCs after oxidized by oxygen through the catalysis of Cu2+. On the basis of this, a colorimetric method was developed for the detection of Cu2+ through measuring the colorimetric signal variation of the TMB-H2O2 reaction. This method exhibited high sensitivity and selectivity toward Cu2+ over a panel of other metal ions. The linear range was 10-100 nmol/L and the detection limit was 5.0 nmol/L (3σ). The above method was also applied to detect real water samples and spiked samples, and the results demonstrated that this method was simple with low cost.