| Summary: | 碩士 === 輔仁大學 === 化學系 === 106 === Gold nanoparticles (AuNPs) have been found to have peroxidase-like activity (as POX activity). Previous studies have verified that sulfur ions (S2-) can inhibit the POX activity of unmodified AuNPs. However, since the catalytic reaction occurs on the surface of AuNPs, the surface modification has a great effect on the POX activity of AuNPs, but few literatures have discussed this. In our experiments, we prepared five different surface functionalization on AuNPs, namely unmodified gold nanoparticles (Naked-AuNPs), gum arabic coated gold nanoparticles (GA-AuNPs), and polyvinylpyrrolidone coated gold nanoparticles (PVP-AuNPs), sodium citrate capped gold nanoparticles (Cit-AuNPs) and cysteamine modified gold nanoparticles (Cys-AuNPs) and used S2- to inhibit the POX activity of AuNPs. At the same time, we also used the X-ray Photoelectron Spectrometer (XPS) to measuring the change of Au(I) content of Au element on the surface of AuNPs, before and after adding S2-. We found that the change of AuNPs with five different surface modifications was ranked from high to low as: Naked-AuNPs > GA-AuNPs > PVP-AuNPs > Cit-AuNPs > Cys-AuNPs. Then the POX activity of AuNPs was tested by the POX substrate TMB and ABTS respectively, and investigate the relationship between the substrate and the charge on the surface of AuNPs. The POX activity of five different surface modified AuNPs was further tested using Terephthalic acid (TA) by Fluorescence Spectrometer. The rank of change of Au(I) content of Au element on different surface modified AuNPs was consistent with the result shown above, which was measured by XPS before and after adding S2-. This shows that the higher Au(I) change before and after adding S2-, the higher POX activity that AuNPs have. This conclusion can provide important strategy for the regulation of the POX activity of AuNPs.
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