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Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cylindrical shapes. This class of nanomaterials has attracted attention because of their extraordinary properties, such as high electrical and thermal conductivity. In addition, development in CNT functionalization chemistry has led to an enhanced dispersibility in aqueous physiological media which indeed broadens the spectrum for their potential biological applications including gene delivery. The aim of this study is to determine the capability of different cationic polymer-grafted multiwalled carbon nanotubes (MWNTs) (polymer-g-MWNTs) to efficiently complex and transfer plasmid DNA (pCMV-βGal) in vitro without promoting cytotoxicity. Carboxylated MWNT is chemically conjugated to the cationic polymers polyethylenimine (PEI), polyallylamine (PAA), or a mixture of the two polymers. In order to explore the potential of these polymer-g-MWNTs as gene delivery systems, we first study their capacity to complex plasmid DNA (pDNA) using agarose gel electrophoresis. Gel migration studies confirm pDNA binding to polymer-g-MWNT with different affinities, highest for PEI-g-MWNT and PEI/PAA-g-CNT constructs. β-galactosidase expression is assessed in human lung epithelial (A549) cells, and the cytotoxicity is determined by modified LDH assay after 24 h incubation period. Additionally, PEI-g-MWNT and/or PEI/PAA-g-MWNT reveal an improvement in gene expression when compared to the naked pDNA or to the equivalent amounts of PEI polymer alone. Mechanistically, pDNA was delivered by the polymer-g-MWNT constructs via a different pathway compared to those used by polyplexes. In conclusion, polymer-g-MWNTs may be considered in the future as a versatile tool for efficient gene transfer in cancer cells in vitro, provided their toxicological profile is established.

Polymer electrolyte membrane fuel cells (PEM FCs) are seen as a suitable technology supporting the transformation towards decarbonised societies. Decision makers face the problem that there is no sound basis of the environmental performance of cutting edge technology available. We developed a comprehensive product system for two types of high temperature (HT) PEM FCs and conducted a life cycle assessment. One system utilizes functionalized multiwalled carbon nanotubes (MWCNTs) as carbon support materials for platinum. The reference product applies carbon black. MWCNTs render possible platinum savings of 27% simultaneously retaining equal performance parameters as for the reference FC.The inventories include all components of a FC starting with the production of the carbon support material, the catalyst powder with platinum nanoparticles, a membrane, a gas diffusion layer, bipolar flow plates up to the FC stack and the FC unit including end of life treatment. Our analysis shows that platinum is the key material in HT PEM FCs and the benefits from platinum savings outweigh by far the impacts on the MWCNT production. The HT PEM FC was adjusted such that it typifies (1) a PEM FC for an electric vehicle (FCEV) allowing comparison with internal combustion engine vehicles (ICVs) and battery electric vehicles (BEVs) or (2) a PEM FC suitable for micro-combined heat and power (m-CHP) to be compared with a Stirling engine. We found an environmental advantage of a FCEV vis-à-vis the ICV, but only if hydrogen is produced with renewable electricity. We found similar environmental impacts for the FCEV and the BEV when both vehicles are propelled with renewable energy. Both m-CHP plants produce similar amounts of useful energy and have comparable environmental performance. Nonetheless, the PEM FC produces more electricity (less heat) than the Stirling engine. System expansion such that both systems deliver equal amounts of electricity and heat resulting in an advantage of nearly 20% for the PEM FC powered system. Thus, the PEM FC technology offers great potential to reduce a personal environmental (and carbon) footprint -a prerequisite on the way of a transformation to more sustainable societies. Broader contextThe prospect of changing electricity production from nuclear and fossil to predominantly renewable energy carriers as planned for example in Switzerland or Germany leads to new requirements of the electricity grid and a new electricity supply pattern. Renewable energy sources release energy congenitally intermittent over diurnal and annual cycles. The PEM FC technology can support the energy turnaround manifold. For individuals our results show that fuel cell electric vehicles provide an environmentally benign technology for individual mobility. PEM FCs in combined heat and power plants are efficient devices to convert a fuel into electricity and heat for housing applications. Both fields of application provide great potential to reduce the individual environmental footprint. Decision makers planning a nationwide strategy...

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The results showed that MAN has desirable in vivo biocompatibility, presenting potential for use as a MDDS, especially in CNS disease therapy.

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In the present study, the bifiller system incorporating various amount of multiwalled carbon nanotubes (MWCNTs) and 3 wt% clay in polypropylene is investigated to obtain composites with multifunctional performance. The dispersion state of two nanofillers in the polypropylene matrix was characterized by applying TEM and Raman spectroscopy. Both composites demonstrate similar rheological behavior with a rheological percolation threshold of / p1 5 1.5 wt% for the monofiller (MWCNTs) and / p2 5 2 wt% for the bifiller systems (MWCNTs and 3% clay). The effect of two nanofillers on electromagnetic and nanomechanical properties was evaluated. Above rheological percolation both type composites show considerable electromagnetic shielding efficiency at small layer thickness due mostly to the addition of MWCNTs. The nanomechanical properties improvement is strongly dependent on the structure formed by MWCNTs in the polymer. The hardness and Young's modulus, measured by nanoindentation, is higher for the bifiller systems in comparison with the monofiller one above the rheological percolation threshold. This was attributed to the continuous network structure formed by interacted MWCNTs and infiltrated fine clay stacks. POLYM. ENG. SCI.,