Functionalization of multi-walled carbon nanotubes with coumarin derivatives and their biological evaluation

Abstract

We report the synthesis and the characterization of different multi-walled carbon nanotubes (MWCNTs) linked to natural molecules, 5,7-coumarins and/or oleic acid, obtained from purified pristine MWCNTs by a cascade of chemical functionalization. The activities of these modified MWCNTs were investigated in vitro on human umbilical vein endothelial cells (HUVECs) by evaluating their ability to influence cell viability and to induce cell apoptosis. Our data showed that pristine MWCNTs are markedly cytotoxic; conversely, the carboxylated carbon nanotubes, much more readily dispersed in aqueous solutions and CNT-Link, the key intermediate designed by us for the drug anchorage, are biocompatible at the tested concentrations (1 and 10 μg ml(-1)).

Synthesis and anti-HIV activity of carboxylated and drug-conjugated multi-walled carbon nanotubes

“…The reported toxic effects of CNT in mammalian cells are controversial, with some reports demonstrating their cytotoxicity [27], whereas others demonstrated their biocompatibility [21,28]. A variety of factors can affect cytotoxicity: type of CNT (single wall or multi-walled), impurities, lengths, aspect ratios, dispersion, chemical modification; furthermore, the different methodologies employed to assay CNT toxicity can also justify these controversial results.…”

“…After removal of the chlorinating agent under vacuum, the acyl derivative was coupled with tert-butyl-2-(2-(2-aminoethoxy)ethoxy)ethylcarbamate according to a previously reported procedure [28]. The protecting group was removed by treatment with HCl 4 M in dioxane to give compound 1; the residue was filtered under vacuum on a 0.1 lm Millipore membrane, carefully washed with dioxane and deionized water; Kaiser test was performed to determine NH 2 loading, which was found to be 1.11 mmol g À1 .…”

Highly untangled multiwalled carbon nanotube@polyhedral oligomeric silsesquioxane ionic hybrids: Synthesis, characterization and nonlinear optical properties

“…The residue was dried under vacuum at 50°C to give 480 mg of c-MWCNT/Na (mean diameter 5-10 nm; average length 0.2-1.0 lm). The total acidity of the functionalized MWCNT was found to be 1.8 mmol g À1 , as determined by titration experiments [34].…”

“…The carboxy-functionalized MWCNT were prepared according to the synthetic method already reported [34]. 500 mg of MWCNT were dispersed in 100 mL of sulfuric acid:nitric acid (3:1 v/v, 98% and 69% respectively), sonicated in a water bath (60 W, 35 kHz) and stirred at 60°C for 6 h. 500 mL of deionized water was then added, the mixture was filtered under vacuum on a 0.1 lm Millipore membrane and carefully washed with deionized water until neutral pH.…”

Nanotechnology Approaches for Antiretroviral Drugs Delivery

“…Among them, carbon nanotubes have shown promise as anti-HIV-1 therapeutics. These carbon nanomaterials offer potential advantages over the more widely studied nanoparticle systems including their ability to cross cellular membranes and shuttle drugs, biomolecules including DNA, small interfering RNA (siRNA) and proteins, into various types of cells such as cancer cells and T cells [124][125][126][127]. Their multimodal conjugation which allows the insertion of more than one type of functional group to the carbon nanotube surface, may be a key property that establishes the superiority of nanopharmaceuticals over conventional agents; in addition, the presence of iron nanoparticles often encapsulated inside the carbon nanotubes allow their use as powerful magnetic carriers in drug delivery and in a range of other magnetic therapies [128].…”