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

Abstract

Bifunctional Gd₂O(CO₃)₂·H₂O/silica/Au hybrid particles were synthesized. The Gd₂O(CO₃)₂·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·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·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 T₁-weighted performance was significantly affected by the Au shell thickness. The relaxivity r₁ increased as the Au shell thickness decreased; 12 nm Au shell particles had the highest r₁ 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·H₂O/silica/Au hybrid particles demonstrated potential as a MR imaging and therapeutic agent.