Cytotoxity of Functionalized CNTs


Carbon nanotubes (CNTs) are very prevalent in today's world of medical research and are being highly researched in the fields of efficient drug delivery and biosensing methods for disease treatment and health monitoring. Carbon nanotube technology has shown to have the potential to alter drug delivery and biosensing methods for the better, and thus, carbon nanotubes have recently garnered interest in the field of medicine.

The use of CNTs in drug delivery and biosensing technology has the potential to revolutionalize medicine. Functionalization of single-walled nanotubes (SWNTs) has proven to enhance solubility and allow for efficient tumor targeting/drug delivery. It prevents SWNTs from being cytotoxic and altering the function of immune cells.

Cancer, a group of diseases in which cells grow and divide abnormally, is one of the primary diseases being looked at with regards to how it responds to CNT drug delivery. Current cancer therapy primarily involves surgery, radiation therapy, and chemotherapy. These methods of treatment are usually painful and kill normal cells in addition to producing adverse side effects. CNTs as drug delivery vehicles have shown potential in targeting specific cancer cells with a dosage lower than conventional drugs used that is just as effective in killing the cells, however does not harm healthy cells and significantly reduces side effects.

Research shows that functionalized carbon nanotubes are non-cytotoxic and preserve the functionality of primary immune cells. Two types of f-CNTs were prepared, following the 1,3-dipolar cycloaddition reaction (f-CNTs 1 and 2) and the oxidation/amidation treatment (f-CNTs 3 and 4), respectively. Both types of f-CNTs were uptaken by B and T lymphocytes as well as macrophages in vitro, without affecting cell viability. Subsequently, the functionality of the different cells was analyzed carefully. It was discovered that f-CNT 1, which is highly water-soluble, did not influence the functional activity of immunoregulatory cells.

In vitro toxicity of single- and multi-walled carbon nanotubes in human astrocytoma and lung carcinoma cells was investigated. The study was undertaken to characterize the physicochemical properties of single-walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs) and functionalized MW (MW-COOH and MW-NH2), and to assess their cytotoxicity in human astrocytoma D384-cells and lung carcinoma A549-cells, using the MTT assay and calcein/propidium iodide (PI) staining. Both the as-received and the modified nanotubes were characterized by means of thermal analysis (TGA), infrared spectroscopy and atomic force microscopy chiefly to check the degree of functionalization. The cells were exposed to the nanomaterials (0.1–100 μg/ml) for 24, 48 and 72 hours in a medium containing 10% FCS. In D384 cells MTT results revealed a strong cytotoxicity (50%) of SWNTs after 24‑hour exposure already at 0.1 μg/ml, without further changes at higher concentrations or longer incubation times. At all time-points MTT metabolism was decreased by 50% by all the other compounds at 10 μg/ml and with no exacerbation at the higher dose. Similar results were obtained with A549 cells.

Multi-walled carbon nanotubes have been investigated in several species for their potential to promote mutagenesis. Studies in spinach, mice, various human cell lines, and rats have shown that MWCNT exposure is associated with oxidative damage, increased apoptosis, chromosome damage, and necrosis. The cytotoxicity was investigated on healthy alveolar macrophage cells obtained from adult guinea pigs for single-wall nanotubes (SWNTs), multi-wall nanotubes (with diameters ranging from 10 to 20 nm, MWNT10), and fullerene (C60) for comparison purposes. Profound cytotoxicity of SWNTs was observed in alveolar macrophage (AM) after a 6-hour exposure in vitro. The cytotoxicity increased by as high as ~35% when the dosage of SWNTs was increased by 11.30 μg/cm2.

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Asian Journal of Biomedical & Pharmaceutical Sciences