I am synthesizing gold and silver nanoparticles by using plant Extract. The plant Extract I have filtered properly with 0.45 um filter before use as reducing agent. When I use different amount of extract different color nanoparticles forms.
- I think that extract is also present there in green synthesized gold/silver colloidal solution (200 ul to 1 ml in 20 ml precursor).
- My question is should I centrifuge and collect particles and then re-suspend in DI water and ultrasonicate it before I do any characterizations of these nanoparticles?
- But It is showing good absorption spectra which is shifting from blue to red and also XRD is matching using this extract containing colloidal gold/silver.
- Is there any difference if I do other characterizations also from this colloidal gold or should I centrifuge, collect and re-suspend it in DI and sonicate to get nanoparticles for characterizations ?
I am confused whether those are the nanoparticles I got after adding extract or I will get particles after centrifugation and re-suspension. Because It is showing good preliminary results(XRD, UV-Vis SEM) even containing that extract.
I would clean the nanoparticles to remove remaining molecules of everything and to determine if the particles are stable enough. centrifugation resuspension is the simplest way to achieve both.
Both plant extract and unreacted silver nitrate are present in colloidal form. Centrifugation helps in removing unwanted materials as NPs are heavier and settles down.
As said by Syed Salman Hashmi both plant extract and unreacted metal ions remain in the colloidal solution.
* These may cause interference in some characterizations. just for example in XRD you may get peak for carbonaceous materials (broad peak at 2 theta around 20 - 30) or you may also get peaks for metal ions (besides zerovalent metal).
* You can not justify the stability of your nanoparticles along with these impurities
* If you are trying for applications like sensing, these impurities will cause interference
Hence it is better to do centrifugation and redispersion
Centrifugation it to remove the waste (nitrate salt unreacted and extract
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