Rivera, Eladio J.Tran, Lesa A.Hernández-Rivera, MayraYoon, DianaMikos, Antonios G.Rusakova, Irene A.Cheong, Benjamin Y.Cabreira-Hansen, Maria da GraçaWillerson, James T.Perin, Emerson C.Wilson, Lon J.2015-07-102015-07-102013Rivera, Eladio J., Tran, Lesa A., Hernández-Rivera, Mayra, et al.. "Bismuth@US-tubes as a potential contrast agent for X-ray imaging applications." <i>Journal of Materials Chemistry B,</i> 1, no. 37 (2013) Royal Society of Chemistry: 4792-4800. http://dx.doi.org/10.1039/C3TB20742K.https://hdl.handle.net/1911/80883The encapsulation of bismuth as BiOCl/Bi2O3 within ultra-short (ca. 50 nm) single-walled carbon nanocapsules (US-tubes) has been achieved. The Bi@US-tubes have been characterized by high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Bi@US-tubes have been used for intracellular labeling of pig bone marrow-derived mesenchymal stem cells (MSCs) to show high X-ray contrast in computed tomography (CT) cellular imaging for the first time. The relatively high contrast is achieved with low bismuth loading (2.66% by weight) within the US-tubes and without compromising cell viability. X-ray CT imaging of Bi@US-tubes-labeled MSCs showed a nearly two-fold increase in contrast enhancement when compared to unlabeled MSCs in a 100 kV CT clinical scanner. The CT signal enhancement from the Bi@US-tubes is 500 times greater than polymer-coated Bi2S3 nanoparticles and several-fold that of any clinical iodinated contrast agent (CA) at the same concentration. Our findings suggest that the Bi@US-tubes can be used as a potential new class of X-ray CT agent for stem cell labeling and possibly in vivo tracking.engThis is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the Royal Society of Chemistry.Journal articlehttp://dx.doi.org/10.1039/C3TB20742K