Over-1000 nm near-infrared fluorescence and spect/ct dual-modal in vivo imaging based on rare-earth doped ceramic nanophosphors

Abstract

In this study, we aimed to develop a dual-modal in vivo imaging based on over-1000 nm near-infrared (OTN-NIR) fluorescence and single photon emission computed tomography (SPECT)/computed tomography (CT). As an OTN-NIR nanophosphor material, Ytterbium and erbium ion co-doped yttrium phosphate nanoparticles (YPO4 NPs) was synthesized by a hydrothermal synthesis method. Biocompatible poly(ethylene glycol) (PEG)/polycation block copolymer and radioactive111In were introduced on the YPO4 NPs surface (PEG-111In-YPO4 NPs). The PEG-111In-YPO4 NPs showed high dispersion stability in physiological saline and excellent radioactivity in any of PBS and FBS solutions. Furthermore, in vivo OTN-NIR fluorescence and SPECT /CT imaging of live mice was performed. Strong OTN-NIR emission from the blood vessel and organs of live mice were observed. Moreover, SPECT/CT images clearly showed the three dimensional images of the live mice. Therefore, PEG-111In-YPO4 NPs is an attractive candidate for the OTN-NIR fluorescence and SPECT/CT dual-modal imaging probe, and the concept can be served as a novel platform for real-time imaging and three dimensional quantitative determinations.