In this study, the antioxidant activity and antimicrobial effect of tellurium dioxide nanoparticles (TeO2NPs) sols were evaluated by oxygen radical absorbance capacity (ORAC) and agar diffusion bioassay method, respectively. The results of ORAC demonstrated that the antioxidant activity of TeO2NPs sols was in a dose-dependent manner and TeO2NPs-gallic acid sol showed stronger antioxidant activity than TeO2NPs-acetic acid sol due to the synergistic antioxidant effect of gallic acid and TeO2NPs. On the other hand, the results of agar diffusion bioassay method demonstrated that the antimicrobial effect of TeO2NPs-acetic acid sol was stronger than that of TeO2NPs-gallic acid sol and the two kinds of TeO2NPs sols could evidently inhibit the growth of some gram negative bacteria and gram positive bacteria which lack nitrate reductase. The antimicrobial mechanism of the TeO2NPs sols might be similar to that of tellurite.
Aqueous nanoparticle suspension of fullerene and its derivatives are currently attracting much attention. To determine the effects of aqueous nanoparticle suspension of a mono-methanophosphonate fullerene and bis-methanophosphonate fullerene (denoted as n-MMPF and n-BMPF, respectively) on the activities of DNA restrictive endonucleases, plasmid pEGFP-N1 was cleaved at a single but differently restrictive site by EcoR I, BamH I, and isozymes Cfr9 I and Xma I, respectively. Both n-MMPF and n-BMPF inhibited the activity of EcoR I, while n-BMPF exhibited stronger inhibition than n-MMPF. Addition of n-BMPF into reaction mixtures inhibited the activities of all the four enzymes, and IC 50 values for EcoR I, BamH I, Cfr9 I and Xma I were 4.3, >30, 11.7 and 8.3 μmol/L, respectively. When EcoR I was completely inhibited by n-BMPF, addition of excess amounts of pEGFP-N1 could not produce the product linear plasmid; however, increase of EcoR I amounts antagonized EcoR I inhibition of n-BMPF. Two scavengers of reactive oxygen species (ROS), mannitol and sodium azide at the concentrations of 2−10 mmol/L, did not reverse inhibition of n-BMPF, implying that this inhibition probably is not correlated to ROS. These results suggested that aqueous nano-fullerenes might act as inhibitors of DNA restrictive endonucleases. mono-and bis-methanophosphonate fullerene, aqueous nanoparticle suspension, DNA restrictive endonucleases, reactive oxygen species
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