Mono-dispersed Ba2 +-doped Nano-hydroxyapatite conjugated with near-infrared Cu-doped CdS quantum dots for CT/fluorescence bimodal targeting cell imaging

Abstract

Nano-hydroxyapatite particles (Ca10(PO4)6(OH)2, nano-HAp), the main inorganic components of human bone and teeth, has attracted much attentions as a kind of biocompatible carrier to construct dual/multi modal bioimaging probes in recent years. However, the currently developed HAp-based probes still have some shortcomings, such as poor mono-dispersion, potential toxicity and none near-infrared emission, which hinder their further applications in the field of bioimaging. In order to solve the above problems and to combine the high space resolution of CT and high sensitivity of fluorescence together, here we developed a novel dual-modal (CT/fluorescence) bioimaging probe based on nano-HAp. Ba2+ as a CT contrast agent was doped into the lattice of nano-HAp, and Cu-doped quantum dots with near-infrared fluorescent emission and hyaluronic acid (HA) were conjugated with the HAp as a fluorescent agent and tumor-targeting ligand individually to realize its near-infrared imaging and tumor-targeting. The as-received Ba2+-doped HAp-QDs-HA conjugates not only well maintained the good dispersion of nano-HAp, but also possessed near-infrared emission at about 700nm, good biocompatibility and photostability. Furthermore, the in-vitro CT and fluorescence cell imaging of the conjugates also exhibited good dual-modal bioimaging and tumor-targeting ability for potential applications in the field of early diagnosis and therapy of cancer.