Audrey Tourrette

Alginate/chitosan polyelectrolyte complexes: a comparative study of the influence of the drying step on physicochemical properties

Polyelectrolyte complexes (PECs) based on Alginate and Chitosan were prepared for biomedical application. These two biopolymers are valuable resources for biomedical applications. In the present work, three PECs materials were produced using three different drying techniques: hot air drying, lyophilization and supercritical CO2 drying. The choice of the drying technique allowed producing different type of structures, with different porosity scale. In order to evaluate their potential as intra-abdominal wound dressings, swelling ability in various media, enzymatic resistance and drug release behavior of the resulting materials was studied. It was shown that the increase of the porosity improved the swelling ability, without altering the resistance of the materials, whereas drug release studies revealed that the majority of the drug was released within the first 24h whatever the drying process.

Biomimetic Apatite-Based Functional Nanoparticles as Promising Newcomers in Nanomedicine: Overview of 10 Years of Initiatory Research

Biomimetic calcium phosphate apatites, analogous to bone mineral, may now be produced synthetically. Their intrinsic biocompatibility and the nanometer dimensions of their constitutive crystals not only allow one to envision applications in bone tissue regeneration, but also in other medical fields such as nanomedicine, and in particular in view of cell diagnosis. In this mini-review, we look back at 10 years of our dedicated research, and summarize the main advances made in terms of preparation, physical-chemical characterizations and biological evaluations of colloidal formulations of biomimetic apatite-based nanoparticles, which we illustrate here with the angle of cancer diagnosis. The confirmed exceptional biocompatibility of these engineered nanoparticles, associated to the possibility to confer them luminescence properties by way of controlled lanthanide doping, and their capacity to be internalized by cells, including with cancer cell addressing abilities (shown here as a proof of concept), underline that biomimetic apatite-based colloidal nanoparticles are particularly promising for nanomedicine applications, for example related to diseased cells diagnosis. Multidisciplinary research on these functional nanoparticles, initiated as described here, has now generated emulation in the scientific community where the concept of apatite nanoparticles for nanomedicine is being, gratifyingly, appropriated.

Biopolymer-based Stimuli-Responsive Polymeric Systems for Functional Finishing of Textiles

The technological developments of the first decade of 21st century are slowly changing the way we live by controlling our surroundings and regulating our every day life with intelligent objects. Smart Materials and Intelligent Structures are novel disciplines which are currently rapidly growing into an interdisciplinary technology. This new technology is being incorporated in contemporary engineering and design with the aim to create the path for materials to gain “intelligent” features. Textile materials also benefit from the rapid advances in a new interdisciplinary technology. Development of textile materials with new advanced functionalities is the perfect example where these base technologies can be brought together by using the knowledge involving surface science and surface engineering at molecular and atomic level. This knowledge is being responsible for developing and creating a new generation of so-called “smart” textile materials. By redesigning textile material surface, operating at microscopic level, many new possibilities emerge for adapting the macroscopic properties of the material to the present needs of the textile industry and thus fulfil current and future end-user expectations. In this context, this book chapter will focus on an innovative strategy for functional finishing of textile materials by application of surface modifying systems (SMS) based on stimuli-responsive polymers.

Nanomedicine: Interaction of biomimetic apatite colloidal nanoparticles with human blood components

This contribution investigates the interaction of two types of biomimetic-apatite colloidal nanoparticles (negatively-charged 47nm, and positively-charged 190nm NPs) with blood components, namely red blood cells (RBC) and plasma proteins, with the view to inspect their hemocompatibility. The NPs, preliminarily characterized by XRD, FTIR and DLS, showed low hemolysis ratio (typically lower than 5%) illustrating the high compatibility of such NPs with respect to RBC, even at high concentration (up to 10mg/ml). The presence of glucose as water-soluble matrix for freeze-dried and re-dispersed colloids led to slightly increased hemolysis as compared to glucose-free formulations. NPs/plasma protein interaction was then followed, via non-specific protein fluorescence quenching assays, by contact with whole human blood plasma. The amount of plasma proteins in interaction with the NPs was evaluated experimentally, and the data were fitted with the Hill plot and Stern-Volmer models. In all cases, binding constants of the order of 10(1)-10(2) were found. These values, significantly lower than those reported for other types of nanoparticles or molecular interactions, illustrate the fairly inert character of these colloidal NPs with respect to plasma proteins, which is desirable for circulating injectable suspensions. Results were discussed in relation with particle surface charge and mean particle hydrodynamic diameter (HD). On the basis of these hemocompatibility data, this study significantly complements previous results relative to the development and nontoxicity of biomimetic-apatite-based colloids stabilized by non-drug biocompatible organic molecules, intended for use in nanomedicine.

Colloidal Apatite Nanoparticles: Insights on Their Interaction with Cells and Artificial Lipid Membranes

Biomimetic nanocrystalline apatites are analogous to bone mineral. They can be exploited not only for bone regeneration applications, but it is also possible to take advantage of their biomimetic features to explore novel domains of research such as in nanomedicine, if the nanoparticles are stabilized as a colloidal formulation. In this contribution, we concentrate on AEP/HMP-stabilized colloidal apatite nanoparticles (NPs) and on their interaction with different types of cells so as to get experimental evidence on their low cytotoxicity, non-proinflammatory potential, and good compatibility with Red Blood Cells. We then started to explore their interaction with an artificial free-standing phospholipid bilayer, as a simplified model for cell membranes: results indicate, for the first time, that these colloidal apatite NPs can modulate phospholipid bilayer membrane properties, and may even favor the permeation of small molecules (illustrated here with luminescent FITC), which could ultimately be exploited for nanomedicine applications in view of enhancing intracellular drug delivery.

New backing layer for transdermal drug delivery systems: coatings based on fatty acid and beeswax on chitosan films

Fatty acids and beeswax are known to improve barrier properties of biodegradable materials. Thanks to their hydrophobic character, they can act as a barrier against water giving to the material more occlusive properties. This work was aimed at preparing fatty acid and beeswax coatings for a transdermal drug delivery system. In order to study occlusive properties of these coatings, water vapor permeability and contact angle measurements were carried out. The most homogeneous coatings were obtained from the beeswax mixture. Coatings made from emulsified beeswax exhibit high hydrophobic properties and relatively good mechanical properties compared to chitosan film without coatings.