Synthesis of Dendritic Nano-objects Dedicated to Horizontal Gene Transfer Between Bacteria in Soil Pollutant Bio-attenuation Processes
Résumé
Superparamagnetic iron-oxide nanoparticles (SPION) with tailored surface chemistry have recently attracted a great deal of attention for their potential biomedical applications including magnetic resonance imaging (MRI) contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, hyperthermia, drug and gene delivery, cell separation and magnetic-field-assisted radionuclide therapy. Our work is aimed at developing a new technology for the magnetic manipulation of bacterial cells marked with specific DNA onto which magnetic nanoparticles have been grafted. With this technology, it will be possible to selectively remove from the indigenous microbial population of a soil the bacteria that have been transformed with this magnetic DNA. The tagging of plasmids comprising genes involved in chlorous pollutant degradation pathway will enable to understand the horizontal gene transfer mechanisms involved in the eviction of hard-to-remove polluants such as Lindane. A dentritic approach for the decoration of the nanoparticles appears promising as the diversity of functionalization brought by the arborescent structure answers simultaneously all the criteria of biocompatibility, low toxicity and specificity. The structure of the proposed dendritic molecules can be divided into 3 parts: a biphosphonate group at the core which allows a strong and stable coupling between the nanoparticle and the dendritic part under various pH and temperature conditions, a PAMAM (polyaminoamine)-derived dendron and then, at the periphery, hydrophilic and biocompatible oligoethyleneglycol chains decorated with arnino or carboxylic groups, allowing an interaction with the DNA through phosphate or arnine groups. It IlUlst be noted that the synthetic organic shell is easily tunable and allows the conjugation of various parts (PAMAM efficiency in DNA-complexation; OEG hydro-soluble and non toxic) in order to associate their advantages. The dentritic approach, compared to the polymeric one, allows a better size control of the decorated nanoparticles (as a function of the generation of the grafted dendron), a better follow-up of the DNA binding properties (as a function of the generation and the physico-chemical properties of the dendrimer) and finally an ensured reproductibility. The synthesis of the dentritic organic shell, its functionalization on iron oxide nanoparticles and their characterization will be presented.