Marshall,
I think the study using the gold nanoparticles also explains why silver chloride is removed by the kidneys. Because the size of the particles of the silver chloride is less than 2 nm. I believe that the size of a silver chloride particle is around 0.3 nm. In the study below, they chose 40nm and 2 nm gold particles expecting to see the 40 nm particles removed by the liver and the 2 nm particles by the kidney. They were surprised when the majority of the 2 nm particles were still removed by the liver. From the nanoparticle study: http://www.particleandfibretoxicology.com/content/4/1/10 "In the present study, we used gold nanoparticles as a model. Gold nanoparticles were considered suitable as a model for studying cellular uptake of nanoparticles because: 1) they are believed to be totally inert, i.e. have no adverse effects [15 <> ]; 2) they can be silver enhanced by AMG to visible sizes [5 <> ,9 <> ,11 <> ]. We decided to use 2 and 40 nm particles in order to test if any biodistribution patterns could be related to particle size. The finding that both 2 and 40 nm particles accumulate overwhelmingly in the Kupffer cells of the liver is somewhat surprising. Even after IP injections, where a substantial part of the particles must be expected to pass through one or more lymph nodes packed with macrophages, AMG silver enhanced gold particles were found only in relatively few macrophages and only in few animals. . . . . . . . . The finding that there was no significant difference in accumulation patterns within the three survival periods applied in our study (1, 4 and 24 hours) suggests that once gold nanoparticles have entered the blood circulation, they will either be trapped by the Kupffer cells in the liver, or if smaller than about 4-6 nm partially be filtrated into the preurine. A study performed by Heinfeld et al. [8 <> ] with 1.9 nm Au particles, supports this suggestion. In their study gold nanoparticle retention in the liver and spleen was low suggesting elimination through the kidneys. This mechanism seems to be very efficient and capable of protecting the rest of the organism from the nanoparticles. . . . . . . . . 8. Hainfeld JF, Slatkin DN, Focella TM, Smilowitz HM: Gold nanoparticles: a new X-ray contrast agent. Br J Radiol 2006, 79:248-253." In the referenced study 1.9 nm particles were removed by the kidney and not by the liver because of their smaller size. Here are the results from the referenced [8] study above: http://www.ncbi.nlm.nih.gov/pubmed/16498039?dopt=Abstract&holding=f1000, f1000m,isrctn "Gold nanoparticles, 1.9 nm in diameter, were injected intravenously into mice and images recorded over time with a standard mammography unit. Gold biodistribution was measured by atomic absorption. Retention in liver and spleen was low with elimination by the kidneys." - Steve N
