Conception de matériaux biohybrides photosynthétiques par immobilisation de biosystèmes végétaux au sein de matrices silicées

Student thesis: Doc typesDoctor of Sciences


Evolution pressure typically forces natural systems to become highly optimized, sophisticated and efficient. Specifically, the living systems are able to perform a series of complex and attractive catalytic reactions. Consequently, their integration into new devices has the potential to produce breakthroughs in both fundamental science and possibly leads to new technologies in diverse fields (environment, energy, health). However, cells, isolated from their native environment, are generally fragile or unsuitable in the development of technologies. In the past few years, abundant researches have proved that encapsulation of biomolecules, enzymes and microorganisms into various artificial matrices can be very attractive to create new functional bio-composites. This ever-growing field of research is very promising in the development of new eco-friendly technologies such as whole cell sensors, depolluting devices, stable bioreactors and artificial organs. The aim of this thesis consists of a fundamental study on the elaboration of functional and stable bio-hybrid materials via the immobilisation of organelles or photosynthetic plant cells within various silica matrices in order to design a photo-bioreactor. The first part of this work was devoted to the development of immobilisation methods adapted for the in situ incorporation of fragile biological species (thylakoids, chloroplasts, cells) within porous silica scaffold. Several inorganic precursors and synthesis parameters were studied in order to determine their effects on the morphological, textural and rheological properties of the silica matrices. Particularly, the bioactivity of entrapped thylakoids was investigated and correlated with the properties of the support. Since these photosynthetic structures are very sensitive, a biocompatible synthesis pathway has been designed to allow the formation of stable hybrid materials. In these conditions, the photochemical activity of thylakoids can be preserved for more than 40 days whereas no enzymatic activity can be detected after 3 days in a free suspension of thylakoids. The second part was focused on the realisation of a solid photobioreactor via the in situ or post-synthesis immobilisation of plant cells (Arabidopsis thaliana). With this in mind, the biological activity and the cell-matrix interactions were investigated by using several techniques. A control of the chemical surface properties of silica has shown to be crucial in order to avoid the mineralization of cell walls and prolong the cellular viability of plant cells. Additionally, the porosity of the matrix was also studied. This parameter is able to control the growth and the confinement of cells within the material. Encapsulated within an organo-modified silica matrix, the photoautotrophic plant cells are able to convert water into O2 and produce valuable compounds from CO2 under light irradiation. In the future, such bio-hybrid gels could play a key role in the development of new sustainable technologies.
Date of Award17 May 2010
Original languageFrench
Awarding Institution
  • University of Namur
SupervisorStephane VINCENT (Jury), Alexandre Leonard (Jury), Alain KRIEF (Jury), Pierre Van Cutsem (Supervisor), STEVE LANNERS (President), Jacques Livage (Jury) & BAO LIAN SU (Supervisor)

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