Anti-Angiogenic Properties of Biofunctionalized Silver Nanoparticles

Studies have shown that silver nanoparticles (AgNPs) elicit a cytotoxic effect. The degree of cytotoxicity is dependent on size, concentration, time of exposure and surface chemistry. AgNPs can also be engineered to selectively interact with specific cell types by surface functionalization with biomimetic targeting moieties. To this end, citrate stabilized AgNPs were functionalized with thiol-containing cyclic RGD peptides by ligand exchange to target αvβ3-integrin receptors on the cell membrane of hemangioendothelioma (EOMA) cells. Confocal microscopy and PCR were used to confirm the expression of the αvβ3-integrin receptors in EOMA cells. Cells were incubated with 20nm citrate stabilized or RGD-AgNPs at variable concentrations and exposure times in serum-free media. An MTS assay was used to quantify the number of surviving cells following exposure via absorbance spectrophotometry. Higher cytotoxic responses correlated with increased nanoparticle concentration and exposure times. RGD-peptide functionalization to AgNP surfaces was demonstrated by an immunoblotting assay; however, there was not significant enhancement in cytotoxicity relative to non-binding RAD control peptides. This could be due to the non-integrin dependent mechanisms of cellular internalization reported for the cyclic RGD peptide surfaces and future work will be aimed at promoting integrin specific internalization utilizing antibodies.