We report in the Nanoscale the in vivo application of the technology of isotopically-barcoded ratiometric silver nanoparticles for quantitative biodistribution studies. In a proof of concept study we used peptides with previously described tissue tropism; one peptide that favors vascular beds of the normal lungs (RPARPAR; receptor neuropilin-1, or NRP-1) and another that is selective for central nervous system vessels (CAGALCY). Equimolar mixtures of the peptide-targeted Ag107-NPs and Ag109 control particles were mixed and injected intravenously. Distribution profiles of Ag107 and Ag109 in tissue extracts were determined simultaneously through inductively coupled plasma mass spectrometry (ICP-MS, both on tissue extracts and on cryosections to obtain spatial information). Internally controlled ratiometric AgNP system appears to be suitable for quantitative studies of the effect of targeting ligands on NP biodistribution, at average tissue concentration and distribution at the microscopic level. The platform might be particularly relevant for target sites with high local variability in uptake, such as tumors.

Schematic representation of the concept of isotopically-barcoded silver nanoparticles for in vivo biodistribution studies (Tambet Teesalu).

Ratiometric in vivo auditioning of targeted silver nanoparticles.Toome K, Willmore AA, Paiste P, Tobi A, Sugahara KN, Kirsimäe K, Ruoslahti E, Braun GB, Teesalu T.Nanoscale. 2017 Jul 20;9(28):10094-10100. doi: 10.1039/c7nr04056c. PMID: 28695222