Quantification of carbon nanomaterials in vivo: direct stable isotope labeling on the skeleton of fullerene C60

Abstract

Concerns over the biosafety of carbon nanomaterials have been raised, due to their unique structure, properties and applications. However, a lack of easily accessible quantification methods for in vivo carbon nanomaterials largely limits the evaluation of their biosafety. Here, for the first time we adopted ¹³C stable isotopic labeling for the quantification of a fullerene in vivo. ¹³C-enriched fullerene C₆₀ was synthesized by arc discharge and purified by high performance liquid chromatography. The ¹³C-enriched C₆₀ was dispersed in tween 80 aqueous solution for animal administration and was then monitored and quantified by isotope ratio mass spectrometry after intravenous injection (i.v.). Our results showed that C₆₀ quickly cleared from the blood circulation with a half-life of 14 min, and selective accumulation in the liver, spleen and lungs was observed, with slight decreases seen within 24 h. The pharmacokinetics of C₆₀ could be evaluated using the two-compartmental model, in which the fast clearance after i.v. from the blood circulation and slow clearance by the uptake in tissues were revealed. The present findings demonstrated the feasibility of using ¹³C stable isotopically labeled carbon nanomaterials such as fullerene to trace and quantitatively monitor their bio-behavior in vivo, and suggested that ¹³C-enriched carbon nanomaterials might bring about a new platform to study the environmental fate of carbon nanomaterials.