Surface modification of Nd3+ activated gadolinium core-shell nanospheres for near-infrared and magnetic resonance dual functional bioimaging system

Visualization techniques are effective tools in diagnosis and therapy for biomedical applications. Due to the unavoidable shortcomings of single optical or magnetic resonance imaging, the introduction of dual functional imaging system is of great significance. Herein a new Gd1-xNdx(CO3)OH@SiO2 core–shell nanostructure were developed to fulfill the corresponding demands. Uniform nanospheres were acquired with surface modification and coated with thickness tunable silica shells. The samples presented strong luminescence penetrating biological tissue, due to the wide spectral region covering NIR I & II window of Nd3+ under 808 nm laser excitation. On the other hand, distinct contrast enhancement could be viewed for in vitro and in vivo MRI trials, which generates from high paramagnetic relaxation of Gd3+ and well dispersibility caused by silica shells. Along with the non-toxicity proved by the low concentration of leaching Gd3+ and nice biocompatibility of silica coated nanospheres, it is a superior candidate for NIR and MRI dual functional imaging platform in biological applications.