Mapping the intracellular distribution of carbon nanotubes after targeted delivery to carcinoma cells using confocal Raman imaging as a label-free technique

Abstract

The uptake of carbon nanotubes (CNTs) by mammalian cells and their distribution within cells is being widely studied in recent years due to their increasing use for biomedical purposes. The two main imaging techniques used are confocal fluorescence microscopy and transmission electron microscopy (TEM). The former, however, requires labeling of the CNTs with fluorescent dyes, while the latter is a work-intensive technique that is unsuitable for in situ bio-imaging. Raman spectroscopy, on the other hand, presents a direct, straightforward and label-free alternative. Confocal Raman microscopy can be used to image the CNTs inside cells, exploiting the strong Raman signal connected to different vibrational modes of the nanotubes. In addition, cellular components, such as the endoplasmic reticulum and the nucleus, can be mapped. We first validate our method by showing that only when using the CNTs' G band for intracellular mapping accurate results can be obtained, as mapping of the radial breathing mode (RBM) only shows a small fraction of CNTs. We then take a closer look at the exact localization of the nanotubes inside cells after folate receptor-mediated endocytosis and show that, after 8-10 h incubation, the majority of CNTs are localized around the nucleus. In summary, Raman imaging has enormous potential for imaging CNTs inside cells, which is yet to be fully realized.

Label‐Free Molecular Imaging of Biological Cells and Tissues by Linear and Nonlinear Raman Spectroscopic Approaches

“…[82] Raman imaging quantified the uptake and localized BSA-stabilized single wall carbon nanotubes (SWCNTs) in human mesenchymal stem cells and HeLa cells. Ag roup of substances based on carbon nanotubes also exhibit intense Raman signals and have received attention for their potential applications in biology,which are discussed here in the context of single cells.…”

Utilizing the folate receptor for active targeting of cancer nanotherapeutics

“…The study results suggest that CNTs can be used as ideal targeted imaging agents that produce a strong MRI contrast. In another study, MWCNTs were targeted to cancer cells using the folate receptor using a novel imaging approach (31). Uniquely, the CNTs were identified using confocal Raman microscopy unlike the typically used confocal fluorescence microscopy, which relies on fluorescently labeled CNTs (31).…”

“…In another study, MWCNTs were targeted to cancer cells using the folate receptor using a novel imaging approach (31). Uniquely, the CNTs were identified using confocal Raman microscopy unlike the typically used confocal fluorescence microscopy, which relies on fluorescently labeled CNTs (31). Wang and colleagues (32) tested surface-enhanced Raman scattering nanoparticles in the detection and characterization of circulating tumor cells (CTC), which act as the pioneer cells of invasive cancer during the development of metastasis.…”

Synthesis and Functions of Well-defined Polymer-drug Conjugates as Efficient Nanocarriers for Intravesical Chemotherapy of Bladder Cancera

“…[27] The FR has been proved to be over-expressed on human urinary bladder carcinoma (T24) cells. [28,29] Herein, the aim of this work is to establish the living polymerization technique of PEG-b-PHPMA with welldefined structure for quantitative introduction of bioactive molecules such as target molecule folate and anticancer drug DOX. Through the precise control of chemical structure and composition, not only the influence of the amount of targeting moiety on cancer cell uptake and the hydrodynamic characters of polymer-drug conjugates were well demonstrated, but also the clinical treatment of bladder cancer could be improved by polymer-drug conjugates because of the macromolecular effect and introduction of target molecules folate.…”