Nontoxic Formulations of Scintillation Nanocrystals for Use as X-ray Computed Tomography Contrast Agents

详细信息    查看全文

• 作者：Jaewon Lee ; Seulgi Choi ; Ki Hyun Kim ; Hock Gan Heng ; Sandra E. Torregrosa-Allen ; Benjamin S. Ramsey ; Bennett D. Elzey ; You-Yeon Won
• 刊名：Bioconjugate Chemistry
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：28
• 期：1
• 页码：171-182
• 全文大小：682K
• ISSN：1520-4812

文摘

X-ray computed tomography (CT) is currently one of the most powerful, noninvasive, clinical in vivo imaging techniques, which has resulted from advances in both X-ray device and contrast enhancement technologies. The present study demonstrates, for the first time, that metal tungstates (such as CaWO₄) are promising contrast agents for X-ray, radiation, and CT imaging, because of the high X-ray mass attenuation of tungsten (W). We have developed a method of formulation, in which CaWO₄ (CWO) nanoparticles (NPs) are encapsulated within a biocompatible poly(ethylene glycol-b-d,l-lactic acid) (PEG–PLA) block copolymer (BCP) capsule. We show that these PEG–PLA-encapsulated CWO NPs (170 ± 10 nm hydrodynamic diameter) produce a higher CT contrast (by a factor of about 2) than commercial iodine-based radiocontrast agents (e.g., Iohexol) at identical molar concentrations of W or I atoms. PEG–PLA-coated CWO NPs are chemically stable and completely nontoxic. It was confirmed that the maximum tolerated dose (MTD) of this material in mice is significantly higher (250 ± 50 mg per kg body weight following a single intravenous (IV) administration) than, for instance, commercially available dextran-coated iron oxide nanoparticles that are currently used clinically as MRI contrast agents (MTD in mice ≈ 168 mg/kg per dose IV). IV-injected PEG–PLA/CWO NPs caused no histopathologic damage in major excretory organs (heart, liver, lungs, spleen, and kidney). When an IV dose of 100 mg/kg was given to mice, the blood circulation half-life was measured to be about 4 h, and more than 90% of the NPs were cleared from the mice within 24 h via the renal and hepatobiliary systems. When intratumorally administered, PEG–PLA-coated CWO NPs showed complete retention in a tumor-bearing mouse model (measurements were made up to 1 week). These results suggest that PEG–PLA-coated CWO NPs are promising materials for use in CT contrast.