Dendrimer-stabilized bismuth sulfidenanoparticles: synthesis, characterization, and potential computed tomography imaging applications

Abstract

We report here a general approach to synthesizing dendrimer-stabilized bismuth sulfide nanoparticles (Bi₂S₃ DSNPs) for potential computed tomography (CT) imaging applications. In this study, ethylenediamine core glycidol hydroxyl-terminated generation 4 poly(amidoamine) dendrimers (G4.NGlyOH) were used as stabilizers to first complex the Bi(III) ions, followed by reaction with hydrogen sulfide to generate Bi₂S₃ DSNPs. By varying the molar ratio of Bi atom to dendrimer, stable Bi₂S₃ DSNPs with an average size range of 5.2–5.7 nm were formed. The formed Bi₂S₃ DSNPs were characterized via different techniques. X-ray absorption coefficient measurements show that the attenuation of Bi₂S₃ DSNPs is much higher than that of iodine-based CT contrast agent at the same molar concentration of the active element (Bi versus iodine). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay and hemolysis assay reveal that the formed Bi₂S₃ DSNPs are noncytotoxic and have a negligible hemolysis effect in the studied concentration range. Furthermore, we show that cells incubated with the Bi₂S₃ DSNPs are able to be imaged using CT, a prominent enhancement at the point of rabbit injected subcutaneously with the Bi₂S₃ DSNPs is able to be visualized via CT scanning, and the mouse's pulmonary vein can be visualized via CT after intravenous injection of the Bi₂S₃ DSNPs. With the good biocompatibility, enhanced X-ray attenuation property, and tunable dendrimer chemistry, the designed Bi₂S₃ DSNPs should be able to be further functionalized, allowing them to be used as a highly efficient contrast agent for CT imaging of different biological systems.