Preclinical molecular imaging of cancer has the potential to increase the understanding of fundamental cancer biology,
elucidate mechanisms of cancer treatment resistance, and increase effectiveness of drug candidates. Optical and
magnetic resonance imaging contain complementary strengths, suitable for gaining a wealth of knowledge when
combined. Here, we demonstrate the inherent contrast sensitivity of single walled carbon nanotubes to absorption based
photothermal optical coherence tomography (PT-OCT), and magnetic resonance imaging spin dephasing contrast (T2).
A spectral-domain OCT system was interfaced with an amplitude-modulated (100 Hz) titanium sapphire pump beam for
PT-OCT imaging. MRI was performed with a commercial 4.7 T animal scanner. With both imaging tools, contrast
agent signal linearity (r2 > 0.95) and nM sensitivity over background (p < 0.05) was experimentally determined with
serially dilute solutions of carbon nanotubes coated in amine-terminated polyethylene glycol. The surface functionalization chemistry for carbon nanotubes is well understood, and molecular targeting has been demonstrated in vitro and in vivo, making carbon nanotubes an attractive agent for molecular imaging in preclinical models. We have demonstrated the initial characterization steps for using carbon nanotubes for multi-modality imaging with PT-OCT and MRI.
Small interfering RNA (siRNA) is potentially a promising tool in influencing gene expression with a high degree of target specificity. However, its poor intracellular uptake, instability in vivo, and non-specific immune stimulations impeded its effect in clinical applications. In this study, carbon nanotubes (CNTs) functionalized with two types of phospholipid-polyethylene glycol (PEG) have shown capabilities to stabilize siRNA in cell culture medium during the transfection and efficiently deliver siRNA into neuroblastoma and breast cancer cells. Moreover, the intrinsic optical properties of CNTs have been investigated through absorption and fluorescence measurements. We have found that the directly-functionalized groups play an important role on the fluorescence imaging of functionalized CNTs. The unique fluorescence imaging and high delivery efficiency make CNTs a promising material to deliver drugs and evaluate the treatment effect simultaneously.