I get silver nanoparticles using plant extratcs, with UV - Vis around 436 nm. TEM also confirms nanoparticle formation, however when I test for antimicrobial activity (e.g. E.coli for example) we measure 1 - 2 mm zone of inhibition. Do I need to centrifuge the nanoparticles before the antimicrobial test?
I think yes, either by centrifuge or other way.Seperation and purification (washing) of Ag NPs is necessary to remove reductant species which may have an effect (positive or negative) on the antimicrobial activity of Ag NPs,and overlap might occur .
Yes you have to centrifuge the extract and prepare AgNPs. after preparation centrifuge and do evaluation. But, you have to be conscious on the condition at which NPs are stable.
Did you get XRD analysis of the Ag NPs you have synthesized?You must be sure first that these NPs were really made. Also you have to separate the Ag NPs from the reaction mixture first, wash them well and then have them be examined as antibacterial agent.
Hello, I tried XRD on the nanoparticles and they seem to be formed.
However still I don't get enough antibacterial activity. I have tried washing with centrifugation (5000G, 20 min) using either distilled water or a mixture of water and Tween 20. Any other suggestions on the washing part (e.g. acetone, ethanol, distilled or dionized water?) Thanks in advance
There are many factors affecting the antibacterial activity of Ag NPs. I was thinking that the plant extract might cover the NPs or has strong interaction with them that the Ag NPs are not so free to stick to the examined bacteria. Perhaps washing with hot water or dilute hydrochloric acid can help to get rid of remained extract. this is just a suggestion and also try to check more than one type of bacteria.
Try to use the dilute solution of capping agent. Increasing the amount of capping agent usually decreased their activity. Then use as such for the antimicrobial test and also wash them with absolute ethanol, dispersed in distilled water and test them