>Magister Scientiae - MSc / Human Immunodeficiency Virus (HIV), which is the cause of Acquired Immunodefiency Syndrome (AIDS) is a major global public health issue affecting over 37 million people worldwide and is responsible for claiming over 32 million lives since the discovery of the disease in 1981. Through effective diagnosis, treatment and prevention HIV is a manageable disease. Today, advanced antiretrovirals, known as HAART, serve as effective, first-line drug regimens, consisting of a variety of viral inhibitors, and have successfully helped viral suppression. However, issues arise with antiretrovirals due to patient non-adherence and the development of drug resistant mutations. Coupled with dormant HIV reservoirs, viral extinction is attenuated. It is therefore essential that effective alternative treatments are investigated. The exploration of nanomedicine for targeted drug delivery has shown an ability to prolong the drug circulation time, target drugs to specific sites in the body, and enhance drug effectiveness. A previous study demonstrated a novel therapeutic strategy that was based on a mutant version of the caspase-3 enzyme that can induce apoptosis in HIV infected cells. This therapeutic strategy has the potential to wipe out reservoirs of HIV infection. However, the therapeutic strategy lacked selectivity because the delivery mechanism was based on protein transduction technology which will result in the nonselective delivery of the drug. In this study, preliminary work towards the development of a targeted nanoparticle delivery system for this mutant caspase-3 enzyme is described. The study describes the synthesis of green fluorescent protein loaded alginate/chitosan nanoparticles that were functionalized with a DNA aptamer intended to target the nanoparticles to CD4 expressing cells, that are also targeted by HIV. The THP-1 cell line was used due to the ability of the cells to express CD4 receptors on the cell surface. The nanoparticles were synthesized through ionotropic gelation. The size, polydispersity, zeta potential and morphology were investigated by Dynamic Light Scattering and Scanning Electron Microscopy, respectively. The strongly negative zeta potential studies revealed stability of the nanoparticles in suspension and Scanning Electron Microscopy results showed an indicative collapse of the polymer network for the empty nanoparticles (i.e. nanoparticles not loaded with GFP), whereas solid, cuboid nanoparticles were shown for the GFP-loaded nanoparticles. Image-based fluorescence cytometry demonstrated that the GFP-loaded nanoparticles bind to the THP-1 cells that express the CD4 receptor. The results obtained are indicative of a potential drug delivery system for HIV treatment however, adjustments would need to be made to the current study to further develop this nanocarrier.

Des couches fonctionnelles hybrides organiques/inorganiques ont été générées à une interface solide/liquide à l’aide d’une nouvelle technique de fabrication ascendante (bottomup) dénommée Croissance de Couche à partir d’une Surface (Surface Grown Layers - SgL)grâce à une modulation très fine de l’interaction électrostatique entre nano-objets decharges opposés en fonction de la force ionique de la dispersion aqueuse. Différents nanoparticules/tubes à la fois cationiques et anioniques et très stables vis-à-vis d’un environnement fortement salin ont été développés. La complexation électrostatique entre ces nanomatériaux a été étudiée en solution et près d’une interface au travers du concept de “transition de dessalage”. Dans un deuxième temps la croissance de couches hybrides à partird’un substrat a été étudiée en comparant l’approche SgL et la méthode classique d’adsorption séquentielle couche par couche (Layer by layer - LbL). Des expériences préliminaires ont montré le potentiel de cette approche dans le développement de substrats fonctionnels. / In this manuscript, one-step bottom-up fabrication of “smart organic-inorganic hybridfunctional layers” at a liquid/solid interface were fabricated via a novel surfacefunctionalization pathway termed as “Surface Grown Hybrid Functional Layers” or SgLthrough fine tuning of electrostatic interaction between “highly stable” and oppositelycharged nanomaterials as a function of ionic strength of the dispersion. Cationic and anionicnanomaterials based on different hybrid nanoparticles/nanotubes that are very stable towardshigh saline environment have been formulated. The electrostatic complexation between theseoppositely charged nanomaterials has been studied in bulk and at an interface through theconcept of “desalting transition” pathway. In a second step, the growth of functional hybridlayers directly from a substrate via the novel SgL approach was then compared with theconventional Layer-by-Layer approach (LbL). Finally the preliminary experiments haveshown the potential applications of generated functional surfaces.