Advances in biodistribution study and tracing methodology of carbon nanotubes

Recent advances in applications of carbon nanotubes (CNTs) require thorough investigation of their in vivo behavior and fate. Biodistribution, as fundamental information for pharmacology and toxicology, should be intensively and systematically studied to accelerate the related researches. In this review, we summarized currently applied methodology in the study of CNTs biodistribution and the achieved biodistribution data. However, the currently used methods, including isotopic labeling, Raman spectroscopy and TEM investigation, can hardly reach a perfect balance of convenience and reliability. We compared the advantage and disadvantage of each method to show diversified choices for different purposes. Based on these techniques, available data suggest that CNTs have a general trend of high reticuloendothelial system (RES) uptake. But their distribution can be dramatically regulated by functionalization of the CNT surface with various molecules. For future biodistribution studies, developing convenient and reliable methods is highly required, and key parameters determining the behavior and fate of CNTs in vivo should be further explored and elicited.