Carbon nanotubes for biomedical imaging: the recent advances

Abstract

This article reviews the latest progresses regarding the applications of carbon nanotubes (CNTs), including single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), as multifunctional nano-probes for biomedical imaging. Utilizing the intrinsic band-gap fluorescence of semi-conducting single-walled carbon nanotubes (SWNTs), fluorescence imaging in the near infrared II (NIR-II) region with enhanced tissue penetration and spatial resolution has shown great promise in recent years. Raman imaging based on the resonance Raman scattering of SWNTs has also been explored by a number of groups for in vitro and in vivo imaging of biological samples. The strong absorbance of CNTs in the NIR region can be used for photoacoustic imaging, and their photoacoustic signals can be dramatically enhanced by adding organic dyes, or coating with gold shells. Taking advantages of metal nanoparticle impurities attached to nanotubes, CNTs can also serve as a T2-contrast agent in magnetic resonance (MR) imaging. In addition, when labeled with radioactive isotopes, many groups have developed nuclear imaging with functionalized CNTs. Therefore CNTs are unique imaging probes with great potential in biomedical multimodal imaging.

Keywords: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; 1D; Biomedical imaging; C18PMH-PEG; CNTs; CTCs; Carbon nanotubes; DOS; DOTA; EPR; GNTs; ICG; MR; MSC; Magnetic resonance; NIR; NIR-II fluorescence; Nuclear imaging; PA; PAH; PCA; PEG; PET; PL–PEG; Photoacoustic; QDs; QY; RBM; Raman scattering; SERS; SPECT; SWNTs; US-tubes; VHSs; carbon nanotubes; circulating tumor cells; density of states; enhanced permeability and retention; golden nanotubes; hMSCs; human MSCs; indocyanine green; magnetic resonance; mesenchymal stem cells; near infrared; one dimensional; phospholipid–PEG; photoacoustic; poly(allylamine hydrochloride); poly(maleic anhydride-alt-1-octadecene)-polyethylene glycol; polyethylene glycol; positron emission tomography; principle component analysis; quantum dots; quantum yield; radical breathing mode; single photon emission computed tomography; single-walled carbon nanotubes; surface enhanced Raman scattering; ultra-short SWNTs; van Hoff singularities.