Recent Posts

Hi Kathie,

Silver nanoparticles (AgNPs) and ionic silver are both potent antimicrobials, but AgNPs are considered to be much less toxic to normal cells than ionic silver as discussed here:

https://iopscience.iop.org/article/10.1088/1742-6596/304/1/012029/pdf

Here is a relevant quote from the research paper :

' The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms. '

In the above quote they show that silver nanoparticles can go as high as 60 mg/L concentration before they start showing their cytotoxicity to cells whereas ionic silver starts to show toxicity at just 1mg/L. Keep in mind that the available retail solutions of either product are measured in parts per million (PPM) and this suggests that the above doses mentioned are possible using over the counter silver products. The above study was an in vitro study. Less is known about what happens to silver as it travels through the human body, but it is known that the smaller ionic silver can readily enter cells in the body whereas the larger AgNPs can not enter cells so readily, especially if they are larger than 50 nm in size. Once inside the cells, the ionic silver can bind to molecules in the cell such as chloride creating silver chloride which is often too large to be able to exit through the cell wall, the way that the original silver ion entered the cell in the first place. This can result in argyria if done long enough at a high enough dose, but that kind of dosing and length of administration would never be done under normal conditions.

Ionic silver is clear and colorless resembling water. Silver Nanoparticles will be anywhere from pale yellow to extremely dark brown in color appearing more like very dark coffee. The darker the color usually the higher the ppm of the solution. Quality silver nanoparticles in the yellow range will also show high clarity of the suspension. The highest concentration of AgNPs I have ever made was 320 ppm and it looks like dark coffee. When diluted back to 20 ppm it looks like a yellow amber color instead of yellow because of the capping agent used to prevent agglomeration at the higher ppm levels tend to give a darker appearance. Properly made AgNPs at 20 ppm will be the color of baby shampoo. Properly made 20 ppm ionic silver will look like water and both products should have high clarity with no, to very low turbidity.

I guess it comes down to personal preference as both are potent antimicrobials. I make both types, but my preference is for AgNPs because of their potential for lower toxicity toward mammalian cells and AgNPs are what is used in the majority of silver studies. I have used high daily dosages of 20 ppm AgNPs in a friend for over two years with no apparent deleterious effects. I would never have used similar dosing of 20 ppm ionic silver for the same length of time.

Art