Silica-coated nanoparticles:

a) Should all silica-coated particles (carbon black, titania, ZnO, and silica itself) be a read across class for environmental dispersal? ecotoxicity ? human toxicity?
b) How to group (e.g. silica-coated ZnO nanoparticles) for environmental dispersal, toxicity, and protein corona formation:
- zeta potential;
- solubility;
- chromatography.

Two Answers

Not unless we can show that the underlying core does not affect the resulting silica shell in terms of its surface characteristics (silanol groups, bond strain, defects, dissolution rate etc, - there is data that shows that adding a fluorescence group alters dramatically the silica structure and dissolution - Mahon, Chem Comm, 2012,48, 7970-7972 ).

query_builder Oct. 25, 2016
perm_identity Iseult Lynch

Iseult is correct. The question becomes the purpose of the read across class. If the purpose is dissolution, then one needs to demonstrate if the silica shell delays/inhibits/retards dissolution within the time period of the test. Secondarily, the silica shell may be stable for the test time period, but eventually dissolve away to the point that it is not a chronic source of toxicity. At present, the silica shell is often not included in the description of the particle, which means the effects in Iseult and my answers are not fully considered.

query_builder Oct. 29, 2016
perm_identity Frederick Klaessig