I made AgNp using the polyol method, it consists in silver nitrate reduced with monoethylene glycol (dispersant aswell ) and stabilized with PVP-k30. The Np colloid presented a brownish colour, but after some weeks of storage the dispersion became green and cloudy. The UV spectra showed a broad band in the 15b synthesis and the TEM analysis brought circular Np's in both synthesis.
The antimicrobial activity remained the same for all the samples aswell as storage conditions.
Hi Vinicius,
The color of silver NPs depends on reduction state and particle size. A change from red-brownish to green could signify agglomeration especially if you see clouding as well. It looks like your system is not stable (chemically or colloid chemically). I have included an article that explains the different colors wrt size and reduction state.
I hope this helps !! Kind regards, Leo
Thanks Leo! The directions you gave me regarding the sedimentation and stability, led me to some interesting information about the relation between the stoke's law and nanoparticle sedimentation. I'll be able to apply it to my work, hopping to develop good results.
Thank you very much! All the best, Vinícius.
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