Research and development item: ③(a-2) Development of measurement methods for toxicokinetics of PEAPOD

Implemented by Shinshu University

Final objective: To evaluate the toxicokinetics of CNTs, we establish a technique for creating PEAPOD with specific atoms or its compound encapsulated in the hollow parts of CNTs to measure toxicokinetics. We compile and release a technical instruction manual on the creation, evaluation, and application of PEAPOD for toxicokinetics testing of CNTs.

Main results:
Non-destructive analysis of the toxicokinetics of fibrous CNTs is difficult with existing measurement techniques. Therefore, to measure toxicokinetics, we developed PEAPOD that encapsulates imaging materials (metallic salts) in hollow parts utilizing the shape of CNTs. Thus far, we succeeded in encapsulating iodine and metals such as gadolinium chloride, platinum chloride, and gold chloride in the hollow parts of CNTs.

When we imaged CNTs with gadolinium chloride encapsulated (Gd-peapods) by magnetic resonance imaging (MRI), a significant increase in signal strength was observed compared with that observed before modification, which suggests that the PEAPOD could be evaluated by MRI. In addition, we used MRI to evaluate the lung of a rat to which Gd-peapods had been administered via the tail vein. Consequently, the lung in which the CNTs had accumulated exhibited an enhanced signal compared with the lung to which CNTs were not administered and the lung to which pristine CNTs were administered. This indicated that peapod-CNTs accumulated in biological tissues and organs could also be evaluated by MRI (Figure ③(a-2) ).

Figure③(a-2) Evaluation of Gd-peapods