Nanotechnology applications have emerged enormously in recent times. Of particular interest is that area that overlaps the areas of nanotechnology, biology and medicine: nanomedicine. One advantage of nanomedicines is it that it can be used as an enabling technology by pharmaceutical researchers and industry to overcome issues associated with the low bioavailability of hydrophobic drugs. In the first part of the current study, nanosuspensions of two of hydrophobic steroid drugs: hydrocortisone and prednisolone were produced. Nanosuspensions were prepared using a bottom-up approach: the anti-solvent precipitation method using microfluidic reactors. Surface modification was carried out on these nanosuspensions using cationic surfactants to obtain nanoparticles with different levels of surface positive charge as indicated by ¿-potential values. Dynamic light scattering (DLS) and transmission electron microscope (TEM) techniques were used to characterize the prepared nanoparticles. Powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) were also used to characterize hydrocortisone nanoparticles. In the second part, cellular uptake of both coated and uncoated nanoparticles by HaCaT keratinocytes cell line was examined and indicated by quantifying the anti- inflammatory effect of nanoparticles on the LPS-induced inflammation. Also, TEM was employed to evaluate the cellular uptake of hydrocortisone nanoparticles. Results showed higher ant-inflammatory effect of coated nanoparticles over uncoated nanoparticles. Furthermore, the anti-inflammatory effect of coated nanoparticles was correlated to the degree of positive surface charge. / Libyan government

L'objectif de cette thèse est d'étendre le champ d'application d'une méthode de simulation mésoscopique, appelée " Stochastic Rotation Dynamics " (SRD), au cas des électrolytes asymétriques en taille et en charge, tels que les suspensions de nanoparticules chargées. La modélisation de ces systèmes est difficile d'une part à cause des interactions à longue portée entre les solutés (interactions électrostatiques et hydrodynamiques), et d'autre part à cause de la différence entre les échelles de taille et de temps des espèces chargées. Nous avons adapté les algorithmes existants et développé de nouveaux algorithmes afin d'étudier les propriétés dynamiques des solutés tels que l'autodiffusion et la conductivité électrique, en gardant avec un bon compromis entre la précision et l'efficacité. Ce travail est financé par le projet ANR « Celadyct ». / The objective of this thesis is to extend the scope of the mesoscopic simulation technique called “Stochastic Rotation Dynamics” (SRD), for asymmetric electrolytes, such as suspensions of charged nanoparticles. The modeling of these systems is difficult, firstly because of long-range interactions between solutes (electrostatic and hydrodynamic interactions), and secondly due to the difference between the size and time scales of charged species. We have adapted the existing algorithms, and developed new ones in order to study the dynamic properties of solutes, such as self-diffusion and electrical conductivity, keeping up with a good compromise between accuracy and efficiency. This work is funded by the ANR project "Celadyct".

No / The latest advances in mesocrystal formation and non-classical crystallization of pre-synthesised nanoparticles have been reviewed with the focus on providing a fuller description of a number of complex systems and their properties and applications through examination of the crystallisation mechanisms at work. Two main crystallization principles have been identified; classical crystallization and particle based aggregation modes of non-classical pathways. To understand the non-classical pathways classical crystallization and its basics are introduced before non-classical pathways, such as oriented attachment and mesocrystal formation, are examined. In particular, the various destabilization mechanisms as applied to the pre-synthesized building blocks in order to form mesocrystalline materials as well as the interparticular influences providing the driving forces are analyzed and compared to the mechanisms at work within classical crystallization. Furthermore, the new properties of the mesocrystalline materials that derive from the collective properties of the nanoparticular building units, and their applications potential are presented. It is shown that this new class of materials has the potential to impact in a number of important areas such as sensor applications, energy conversion, photonic crystals as well as for energy storage, optoelectronics and heterogeneous catalysis or photocatalysis.