A study of Gd loaded silica nanoparticles for both optical and magnetic resonance imaging of cells

•A new method was proposed to construct multifunctional silica nanoparticles for dual fluorescence and MRI imaging.•Gd-silica nanohybrids via polyelectrolyte capping provides the enhancement of T1 relaxivity due to the increase in hydrophilicity.•Polyelectrolyte encapping method was adopted to decorate Gd on the corona of Gd-silica nanohybrids.•In vivo distribution of the Gd-silica nanohybrids was investigated by ICP-MS.

We have developed fluorescent nanoparticle-based T1 contrast enhancing magnetic resonance imaging (MRI) agents, for the purpose of dual imaging in vivo. Gd(III) chelated silica nanoparticles were successfully synthesized with dual-mode diagnostics feasibility in MRI and fluorescence imaging analysis. Gd-chelated silica nanoparticles were studied, which were formed via polyelectrolyte encapping methods. A 9.4T micro-image instrument was used to investigate the T1 contrast enhancement effects of the Gd-chelated silica nanoparticles. The resulting Gd chelated nanoparticles were used in cell tracking and bio-distribution experiments with dual mode imaging of A549 lung cancer cells and mouse models. These Gd-silica nanoparticles are promising dual mode materials, functioning as T1 MRI contrast agents and organ specific contrast agents.