Fabrication of Gd2O(CO3)(2)center dot H2O/silica/gold hybrid particles as a bifunctional agent for MR imaging and photothermal destruction of cancer cells

Bifunctional Gd2O(CO3)(2)center dot H2O/silica/Au hybrid particles were synthesized. The Gd2O(CO3)(2)center dot H2O cores were decorated with a silica layer on the surface through the condensation of TEOS and reaction with APTES to produce Gd2O(CO3)(2)center dot H2O/silica hybrid particles. The silica-coated particles were then conjugated with gold nanoparticles serving as seeds to react with HAuCl4 solution for the formation of Au shells leading to Gd2O(CO3)(2)center dot H2O/silica/Au hybrid particles. The thickness of the Au shells were set to 12, 26, 63 nm by adjusting the HAuCl4 amount. For in vitro MRI measurements, the T-1-weighted performance was significantly affected by the Au shell thickness. The relaxivity r(1) increased as the Au shell thickness decreased; 12 nm Au shell particles had the highest r(1) value. The hybrid particles also showed the capability of absorbing near-infrared (NIR) radiation for photothermal destruction of cancer cells. It was found that the Au shell thickness also strongly influenced the NIR optical absorption and photothermal effect. At a fixed particle number, particles with a 63 nm Au shell exhibited the best photothermal performance. When the particle weight was fixed, 12 nm Au shell particles led to the optimum photothermal cancer destruction. Gd2O(CO3)(2)center dot H2O/silica/Au hybrid particles demonstrated potential as a MR imaging and therapeutic agent.