Novel synthesis of silica-coated Eu:Gd2O3 nanoparticles by polyol route at low temperature for bimodal cancer imaging

This article reports the novel synthesis of europium doped gadolinium oxide (Eu:Gd2O3) nanoparticles at low temperature by the polyol method for the first time. The role of triethylene glycol (TEG) on the magnetic and optical properties was studied. The cytotoxicity of the nanoparticles and their applications in magnetic resonance imaging (MRI) and optical imaging was also reported. Silica is coated over the nanoparticles to improve the biocompatibility. Spherical nanoparticles with an average diameter of ~40 nm were synthesized and silica with thickness around 5 nm was coated on the nanoparticles. In the photoluminescence studies, the characteristic emission of Eu3+ ions at 612 nm due to the 5D0 → 7F2 transition was observed. The lifetime of the uncoated and silica-coated nanoparticles were found to be 1.14 and 0.83 ms respectively. The cell viability was assessed in MG63 osteosarcoma cell line by the MTT assay. The results show that the silica-coated nanoparticles possess negligible toxicity till the concentration of 200 μg ml−1. Within this limit, as the concentration of the nanoparticle is increased, the MRI results reveal bright contrast images with the relaxivity value of 4.8 mM−1 s−1, which is higher than the commercially available contrast agents.