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Carbon nanotubes (CNTs) have been used for a plethora of biomedical applications, including their use as delivery vehicles for drugs, imaging agents, proteins, DNA, and other materials. Here, we describe the synthesis and characterization of a new CNT-based contrast agent (CA) for X-ray computed tomography (CT) imaging. The CA is a hybrid material derived from ultrashort single-walled carbon nanotubes (20–80 nm long, US-tubes) and Bi(III) oxo-salicylate clusters with four Bi(III) ions per cluster (Bi4C). The element bismuth was chosen over iodine, which is the conventional element used for CT CAs in the clinic today due to its high X-ray attenuation capability and its low toxicity, which makes bismuth a more-promising element for new CT CA design. The new CA contains 20% by weight bismuth with no detectable release of bismuth after a 48 h challenge by various biological media at 37 °C, demonstrating the presence of a strong interaction between the two components of the hybrid material. The performance of ...

As the most widely used synthetic material on the planet, concrete poses a serious societal concern regarding its significant environmental footprint. There is a global urgency to develop innovative strategies to develop greener concrete with improved strength and durability (to do more with less). In this context, reducing cement hydrate porosity via tuning the kinetics and morphology of its building blocks is highly desired but a fundamental challenge. Herein, we propose for the first time a unique pathway involving in situ seed generation and subsequent controlled overgrowth, demonstrating the morphogenesis of cement hydrate ranging from cubic, rhombohedral, dendritic to core–shell-like structures, which are all expressed in a single morphology diagram. Probing the mechanics of individual particles versus their assemblies at larger scales reveals that the low porosity attained by the formation of face-to-face close-packed cubic particles leads to significantly improved mechanics, opening up an entirely new phase space for bottom-up engineering of concrete while curbing its negative environmental impacts.

Carbon nanotubes (CNTs) are one-dimensional cylindrical tubes of carbon atoms bonded together, similar to graphene and have drawn great interest for their use as medical agents due to their potential for a variety of clinical applications. Researchers have used CNTs as therapeutic agents, both by taking advantage of their powerful light-driven effects and using them as carriers for peptide and small molecule drugs. As progress toward these applications continues, monitoring CNTs in vivo will also be important to evaluate their potential toxicity, therapeutic activity, and any physiological side effects that the material may cause in various organs. Furthermore, CNTs provide a versatile platform for combining therapeutic and diagnostic capabilities for so-called theranostic agents, a field which has seen a surge of activity in recent years. Here, we focus on CNT-based materials functionalized for therapeutic, diagnostic, and theranostic applications in cancer, while also discussing the future directions and challenges of CNT medical agents in general. As evidenced by the body of work presented in this Chapter, CNTs may have a future as multimodal anti-cancer agents, thereby increasing the efficacy of current therapies and imaging techniques while also decreasing harmful side effects that often impede effective patient care.

A gentle, rapid method has been developed to introduce a polyacrylic acid (PAA) polymer coating on the surface of gadonanotubes (GNTs) which significantly increases their dispersibility in water without the need of a surfactant. As a result, the polymer, with its many carboxylic acid groups, coats the surface of the GNTs to form a new GNT-polymer hybrid material (PAA-GNT) which can be highly dispersed in water (ca. 20 mg·mL−1) at physiological pH. When dispersed in water, the new PAA-GNT material is a powerful MRI contrast agent with an extremely short water proton spin-lattice relaxation time (T1) which results in a T1-weighted relaxivity of 150 mM−1·s−1 per Gd3+ ion at 1.5 T. Furthermore, the PAA-GNTs have been used to safely label porcine bone-marrow-derived mesenchymal stem cells for magnetic resonance imaging. The labeled cells display excellent image contrast in phantom imaging experiments, and transmission electron microscopy images of the labeled cells reveal the presence of highly dispersed PAA-GNTs within the cytoplasm with 1014 Gd3+ ions per cell.