Advertising Claim: “Our product has Angstrom (subnano) size colloidal silver”.
They are not real colloids. They are likely solutions of silver salts, or ionic silver. One Angstrom is 0.1 nm, a tenth of a nanometer. Angstrom size particles mean particles less than 1 nm in size. The probability of someone producing stable angstrom size silver particles is slim to none, almost impossible. This performance would be at the frontiers of heavily scrutinized peer review science (quantum dots) and would bring attention from the scientific world quickly. If someone would prove the existence of stable sub-nano silver particles they will certainly publish this finding or experiments in prestigious peer review scientific articles and will be recognized in their scientific field as a major contributor. For someone to claim it on the internet without any credible proof is stretching the believability factor to say the least. Hey, let’s say it as it is: they are lying!
For the more science inclined of you an atom of silver is about 0.3 nm. A silver ion is 0.3 nm.
Now, silver atoms can clump together but not in random order. They start to form clusters of a very definite number of atoms like 4-5, 9, 27 , etc, so called “magic numbers”. In other word a cluster of 4-5, or 9 atoms is much more stable than one of 6 or 7 atoms. Moreover, an aggregate of 27-35 atoms barely gets to .07-0.8 nm or 8 Angstroms. These are the so called atomic nucleus or clusters and are NOT considered particles. There is a special chemistry field dedicated to atomic clusters. If you heard of “quantum dots” this is what they are talking about. These clusters are immensely unstable and reactive with one another and with the environmental impurities or proteins. To claim that out of a few atoms in a cluster instead of reacting with proteins instaead they are stable and also liberate 1 atom or ion at a time is ludicrous. Remember, even when clusters shed atoms, it is not one by one to give individual ions, because they have to stay within the constraint of the “magic numbers” determined by attraction forces. Therefore, they shed 4,5, or more atoms clusters, in other words the clusters, form and un-form continuously, but not by one atom at a time.
A 3-4 nm particle will have likely thousands of atoms and a 10 nm particle tens of thousands of atoms. They regularly shed a few ions per thousand atoms, a number more than enough to have antibacterial effect.
The clusters become particles and become visible when the clusters become particles, meaning they grow to a few hundred atoms, which happens around 1.5-2 nm diameter. In general small clusters dissolved in solution form bigger ones by clumping through a process named “ripening”.
Particles smaller than 1 nm cannot exist by themselves, unless stabilized by a ligand. Even if this is the case they are not ions anymore, therefore are not having antibacterial properties.
A silver atom has a diameter of 2.9 Angstroms or 0.29 nm, roughly a third of a nanometer. In order for silver particles to have sizes less than 1 nm (~ 3 atomic diameters), they would have to be clusters of silver atoms containing between 4 and 15 atoms. Such small clusters of a few silver atoms are way too unstable due to their high energy.
There are just a few reports published of such silver clusters published (for example by A. Henglein in Berichte der Bunsengesellschaft für physikalische Chemie 05/2010; 94(5):600 – 603. DOI: 10.1002/bbpc.19900940513). They are usually produced in very restrictive and difficult experimental condition (intense radioactive excitation in exotic closed reactors for example). Even then those particles cannot be seen, their presence ONLY being detected based on specific absorption plasmon bands at 360-390nm.
The lower the number of silver atoms in a particle the higher their energy is and their potential to interact with another cluster or with the environment is increased by orders of magnitude. At such low numbers of atoms in a particle, the said particles cannot and are not stable due to their high potential energy. They behave more like a fluid cluster stealing clusters of atoms from each other and constantly changing their size and shape in attempt to lower their energy.
Only when the particles reach several hundreds and ideally thousands of silver atoms they become stable in time dispersed in water. When this happens the particles are typically above 5 nm in size.
There are two accepted methodologies to prove the existence of dispersed silver nanoparticles. One is by showing the plasmon resonance spike by spectrometry. The other is direct visualization. With all the advances of science there are not too many electron microscopes capable to effectively observe Angstrom size particles at this time.
Direct visualization usually is achieved by using the scanning electron microscope (SEM) but SEM cannot visualize particles less than 1 nm as the resolution of the method is typically above 1.0 nm. More sensitive is the Transmission Electron Microscope (TEM) or Field emission (FESEM). Very good (and very expensive) TEM instruments have typically a resolution of ~0.7 nm, or 7 Angstroms. Claiming that one can really detect objects of a size similar to the limit of the instrument resolution (7 Angstrom resolution and 7 Angstrom particles or less) is like saying that is easy or even possible for you to see in detail a nonfunctioning pixel on a TV or computer from a distance. It is simply not credible.
Additionally, if someone wants to visualize Angstrom-size particles using TEM they absolutely need to deposit the particles on a conductive substrate. That alone can cause false images when the high energy electron pass through both particles and substrate. Basically at 1 nm resolution one does not know if they see the particles in question or they see substrate structures/artifacts.
So, since direct visualization is generally out of question the only other way for the “scientists” on the internet to claim “Angstrom “-size is to show a clear, well-defined plasmon resonance bands below 380 nm. The spectrum of clusters should be even lower, in the 340-350 nm range.
Since they are not providing any of the above type of clear scientific evidence, we conclude that their claims to Angstrom sized silver particles are nothing but bogus made by fake “scientists” that have little understanding of what real science is.
“This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”