The synergistically improved afterglow and magnetic resonance imaging induced by Gd3+ doping in ZGGO:Cr3+ nanoparticles

Gd3+ and Cr3+ codoped zinc gallogermanate (ZGGO:Cr3+, Gd3+) nanoparticles were prepared by a hydro thermal method in combination with a subsequent vacuum annealing. It is found that Gd3+ doping not only endows ZGGO:Cr3+ nanoparticles with magnetic property, but also results in the decreased nanoparticle size and the enhanced near infrared (NIR) afterglow intensity. Strikingly, amino group functionalized SiO2 layer coating enabling Gd3+ doped ZGGO:Cr3+ nanoparticles well dispersed in water enhances persistent luminescence which is because of the weakened quenching effect of OH- groups in water. Validation of high-quality bioimaging was demonstrated using the surface functionalized Gd3+ doped ZGGO:Cr3+ nanoparticles dispersed in human serum albumin (HSA). In particular, it is found that the longitudinal relaxivity (7.33 s(-1)(mM)(-1)) of Gd3+ doped ZGGO:Cr3+ nanoparticles is higher than that of commercial magnetic resonance imaging (MRI) contrast agent (Gd-DTPA) and it leads to the high-quality in vitro T-1-weigthed images.