Optical imaging, biodistribution and toxicity of orally administered quantum dots loaded heparin-deoxycholic acid

Quantum dots (QDs) are considered to be one of the most promising optical imaging probes for biological and biomedical applications. However toxicology is the major concern that limits biological application. Though couple of studies have reported focusing on intravenous administration but, in this study, we have observed toxicity of orally administered QDs for the very first time. QDs were loaded into heparin-conjugated deoxycholic acid (QLHD) conjugates. The orally administered Q-LHD nanoparticles were absorbed through bile acid transporter of small intestine. In vitro genotoxicity was observed by chromosomal aberration and comet assay to learn effect of quantum dot in cell mutation. The amount of cadmium content in different organs was also measured by inductive coupled plasma mass spectroscopy. To observe physiological changes, complete blood count, serum biochemistry and organ histology of Q-LHD treated rats were performed accordingly. The in vivo biodistribution results confirm any acute toxicity or significant variations were noted in the rats. Furthermore, oral administration of the Q-LHD nanoparticles does not cause appreciable toxicity, showing no mentionable histological changes of the organs at 45 days after single dose. Though this current study reveals, potential toxicity of Q-LHD nanoparticles is no longer a limiting factor for extending application of QDs in biomedical imaging but long term in vivo genotoxicity studies further required.