Optically and magnetically doped organically modified silica nanoparticles as efficient magnetically guided biomarkers for two-photon imaging of live cancer cells

We report here solution-phase synthesis of multifunctional nanoprobes for imaging live cancer cells. More specifically, quantum dots (QDs) and magnetite (Fe₃O₄) nanoparticles were coencapsulated within organically modified silica (ORMOSIL) nanoparticles. These optically and magnetically doped ORMOSIL nanoparticles were systematically characterized. These ORMOSIL nanoparticles were used for magnetically guided in vitro delivery to a human cancer cell line. Two-photon imaging was used to confirm the uptake of nanoparticle-doped ORMOSIL nanoparticles into the cancer cells. We also demonstrate mat synergistic interaction of both magnetic targeting and transferrin-receptor (TfR)-mediated targeting results in robust in vitro cellular uptake, which is significantly higher than that obtained using these two targeting modes individually. Our cell viability study indicates them to be nontoxic. The results illustrate a promising biocompatible nanoparticle platform where multiple imaging and targeting agents can be coincorporated, with the purpose of efficient two-photon bioimaging and magnetically assisted targeting.