Author : Davide Pantarotto
Publisher :
ISBN 13 :
Total Pages : 205 pages
Book Rating : 4.:/5 (834 download)
Book Synopsis Synthesis, Characterisation and Biological Activity of Functionalised Carbon Nanotubes by : Davide Pantarotto
Download or read book Synthesis, Characterisation and Biological Activity of Functionalised Carbon Nanotubes written by Davide Pantarotto and published by . This book was released on 2005 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNT) consist of graphene sheets rolled-up into a tubular form. Since their discovery, they appeared immediately as an interesting material for technological applications, including for instance the fabrication of nanoelectronic components. Recently, CNT have also attracted much attention for their potential in biological applications. The main difficulty to integrate this material into biological systems derives from its complete lack of solubility in organic solvents and aqueous solutions. The ability to solubilise and separate individual CNT is still a great challenge. A very general way to achieve this is by organic functionalisation, which is a rapidly expanding field.In this thesis, I focused my interests on the synthesis and use of the first water soluble side-wall functionalised carbon nanotubes. I employed the 1,3-dipolar cicloaddition of azomethine ylides to carbon nanotubes. I have demonstrated that it is possible to further derivatise them by coupling single N-protected amino acids. This was the first step towards the preparation of covalently linked peptide-carbon nanotube conjugates. In this context, I have developed a powerful strategy for linking bioactive peptides to carbon nanotubes for immunological applications.Immobilisation of peptides to the external walls of carbon nanotubes may find interesting applications in diagnostics, vaccine and drug delivery or multipresentation of bioactive molecules.For this aim, peptides with immunological properties were selected for their coupling to the external surface of the CNT. The immunological reactivity and the peptide recognition were assessed by a peptide specific antibody using surface plasmon resonance and ELISA test.These experiments showed that the peptide linked to CNT retain its conformational characteristics for antibody recognition. Furthermore, biological studies performed in vivo demonstrated that CNT-peptide conjugates elicited high antibody titers. Significant pathogen neutralising capacity was observed for the antibodies induced by CNT-peptide conjugates. This highlights: 1) the potential of carbon nanotubes for vaccine delivery, and 2) the importance of antigen presentation in vivo for the induction of antibodies with the right specificity.Functionalised carbon nanotubes have been showed able to cross the cell membrane and to accumulate in the cytoplasm or reach the nucleus without being toxic for the cell up to 10 μM concentration. These findings highlight the potential use of peptide-carbon nanotube conjugates for diagnostic purposes and pave the way for their application in vaccine and drug delivery. Although the elucidation of the mechanism of entry requires further investigations, I excluded active ATP dependent endocytosis. This is because inhibitors of endosome-mediated translocation and decrease of the incubation temperature did not prevent cellular uptake of the different functionalised CNT. In addition, TEM images revealed the tubes crossing the cell membrane as nano-needles without any perturbation or disruption of the membrane.Cell viability after treatment with functionalised nanotubes has also been largely investigated. Highly soluble functionalised CNT in aqueous biological media exhibited notably reduced cellular toxicity in vitro. Cell viability was studied using flow cytometry.Following the synthesis of positively charged carbon nanotubes I investigate their interaction with plasmid DNA. The cationic-anionic interaction between CNT and DNA has been characterised by different techniques both qualitatively and quantitatively. TEM, photocorrelation spectroscopy, SPR and electrophoresis allowed to describe the stability of the CNT-DNA complexes. The condensation of genetic material onto the carbon nanotubes was then confirmed and biological test were performed. The excellent ability of the ammonium functionalised carbon nanotubes to enter cells and potentially reach their nuclei was exploited for the delivery of plasmid DNA. In vitro experiments showed a high level of gene expression when mammalian cells were transfected with DNA-CNT complexes. The following success obtained in in vivo treatment of mice, highlighted the possibility to use this system for gene delivery in gene therapy. Preliminary comparative gene expression data between functionalised CNT:DNA and commercially available lipid:DNA delivery systems showed that our first generation CNT-based gene delivery system is less efficient for in vitro transfection than the lipid:DNA system. However, there is a lot of room for further improvement of the carbon nanotube system for gene delivery.In conclusion, in this Thesis it was possible to develop and characterise a new chemical macromolecular architecture exploitable as new tool for molecular delivery, and molecular recognition. The further development of carbon nanotube chemistry, the optimisation of their interaction with biomolecules and their use in biomedical applications represent the future perspectives of this research.
