Design of supramolecular nanomaterials : from molecular recognition to hierarchical self-assembly

In the present thesis, are reported new strategies for the design of nanostructures to partly address environmental issues. The work carried out has been divided into three parts: the design of cyclodextrin (CD)-based polymeric materials, the molecular engineering of a pyrene derivative for the formation of self-assembled nanostructures and the design of smart nanocarriers.
Considerable efforts have been devoted to the design of molecular receptors capable of specific recognition of a wide variety of targets ranging from small inorganic ions to large biomolecules. These molecular receptors have been widely used to produce (nano)materials with superior molecular recognition properties. While these materials have been extensively studied for biomedical applications, their use in environmental sciences or biotechnology has been, to some extent, neglected.
Supramolecular materials, because of their superior molecular recognition properties may find a wealth of new applications for the selective removal of harmful or valuable targets from industrial waste streams. While the specific recovery of valuable chemicals from waste streams represents an environmentally-friendly and potentially economically-relevant alternative to synthetic chemical productions, it remains a largely unmet challenge. This is partially explained by the complexity of designing sorption materials able to target one specific compound and able to function in complex matrices.
In this manuscript, is reported the synthesis of a series of CD-based polymers (CDPs) designed to selectively extract phenolic compounds from a complex organic matrix that is OMW. In order to endow these polymers with selective adsorption properties, several monomers and cross-linkers were screened and selected. The adsorption properties of the CDPs produced were first tested with selected phenolic compounds commonly found in OMW, namely syringic acid, p-coumaric acid, tyrosol (TY) and caffeic acid. The selected CDPs were subsequently tested for their ability to adsorb phenolic compounds directly from OMW, which is known to possess a high and complex organic content. Adsorption models and adsorption kinetics were studied and allowed to set a new method on a pilot plant. It was demonstrated through liquid chromatography-mass spectroscopy (LC-MS) analyses that efficient removal of phenolic compounds from OMW could be achieved but also that two compounds, namely TY and hydroxytyrosol (HT), could be selectively extracted from OMW. The chemical oxygen demand (COD) level which is correlated to the amount of organic compounds was also reduced in the recovered fractions after extraction of the phenolic compounds, which makes the recovered waters relevant for irrigation purposes.
The use of CD-based polymeric materials for the removal of valued added molecules could represent a new approach that will benefit from the ease of production of CDP and cost.
Nature represents an inexhaustible source of inspiration for elegant hierarchically assembled structures and biology is replete with numerous examples of highly complex self-assembled structures. From cell membranes to proteins and viruses, the precise internal organisation of these biological structures is based on non-covalent interactions of subunits. Self-assembly strategies have been extensively exploited for the creation of supramolecular entities due to the complex synthesis of large structures through covalent synthetic strategies. Bottom-up approaches permit to build large and complex supramolecular assemblies through the interactions of building blocks.
The accurate molecular design of organic building blocks is of great importance for the creation of large supramolecular entities with precise dimensional organisation. In this PhD thesis, we report the synthesis and template-free hierarchical self-assembly of a novel pyrene derivative into well-defined nanorods. The formation and the three dimensional packing of this pyrene derivative into nanorods were studied by means of fluorescence and UV-Vis spectroscopy, scanning electron microscopy, single crystal and powder X-ray diffraction studies.
Nowadays oil and hydrocarbons cover most of our energy needs. In 2008, the world demand reached 85.62 million barrels/day.[1] Consequently spill accidents cause also considerable damages and water contamination by oil spills represents a major global problem. Several approaches for the degradation of oil spills are available including mechanical removal, wiping with absorbent materials or booming and skimming, but these techniques stay fairly limited in efficiency. Besides these methods, bioremediation has emerged as one of the most promising treatment for oil spill. Bioremediation is divided into two branches, biostimulation and bioaugmentation. We propose in this thesis an alternative way to overcome dilution related issues in biostimulation to degrade hydrocarbons through the stimulation of the microbial growth to increase the rate and efficiency of hydrocarbons degradation. The system would be able then to target specifically the oil phase and avoid any dilution of the needed nutrients into the sea, which should lead to a higher performance of the bacteria.
We reported in this manuscript the synthetic strategy to produce what we named "Smart Gates Particles" (SGPs) that can act as nanocarriers and deliver specifically the nutrients to bacteria. The loading and kinetic releases of the nutrients contained in the SGPs have been studied in different environments, water and mixture oil/water. The design of such particles represents an alternative and ecological way to overcome the dilution or the non-targeted release of nutrients for oil-degrading bacteria.