Title : Functionalized magnetic composites with tailored size and shape and their applications
Abstract:
The scientific interest in nanoparticles (NPs) in general and magnetic nanoparticles (MNPs) in particular, developed these materials as important tools in various fields such as medicine, bio detection, catalysis, agriculture and environment. These materials may have certain limitations, such as aggregation problems, low mechanical and chemical resistance, toxicity, complex and expensive preparation methods. Therefore, the development of new composite magnetic systems that overcome the limitations of classical materials and/or preparation methods, well adapted to the targeted application has become a necessity and the focus of our research. To overcome the aggregation problems of MNP, we replaced the classical co-precipitation synthesis method of NPs with thermal decomposition method, which provides a much more rigorous control over the shape and especially the size of the nanoparticles. Using thermal decomposition method, nanoparticles with various shapes, such as spherical, polyhedral and cubic with size ranging from 10 to 100 nm with uniform size distribution were synthesized. Since the thermal decomposition method provides MNPs with hydrophobic properties, their surface being coated with a layer of oleic acid, for applications requiring hydrophilic particles, it was necessary to transfer them into hydrophilic nanoparticles. Thus, the transfer of hydrophobic into hydrophilic nanoparticles was achieved by the oxidative scission reaction of the double bond, which converts unsaturated oleic acids covering the nanoparticle surfaces to carboxylic acids. Carboxyl groups are one of the most common functionalities used in biomedical applications, but if the targeted application requires, the surface of MNPs can also been functionalized with amino groups with (3-Aminopropyl) triethoxysilane molecular layer that presents a free amino terminal group. For more specific applications such as bio detection of some bio molecular species and/or controlled drug delivery as a specific approach in theragnostic applications, the surface of MNPs have been functionalized with different biocompatible polymeric layers with special properties (thermo and pH responsive or electro conducting) such as polyethylene glycol, poly acrylic acid, poly(N-isopropylacrylamide), polypyrrole which result in decreased surface toxicity and provide special properties for specific applications. For applications in environmental quality control, MNPs can be used as specific tools for magnetic separation of environmental pollutants. In this context, their surface is functionalized with specific molecules for direct capture of pollutants such as nitrites and nitrates from polluted waters or even with hydrophobic layers (polystyrene, polypyrrole, methacrylic acid) for the capture of waste oils. A highly innovative approach is represented by magnetic clusters (MCs), consisting of several hundred magnetic nanoparticles with superparamagnetic properties, self-assembled as MCs of up to 100 nm. The MCs have the advantage of improved magnetic response of particles, while keeping the superparamagnetic behavior. Also, their surface can be functionalized specifically for the desired application, so in our research we have coated them with hydrophilic molecular layers (sodium lauryl sulphate), with inorganic SiO2 layer for dental or security paper applications or with other hydrophilic and/or hydrophobic polymeric layers for depollution applications.
Audience Take Away Notes:
- The presentation will illustrate new, innovative, environmentally friendly synthesis methods for obtaining magnetic composite materials with improved properties
- The audience will learn new simple and efficient preparation processes of different magnetic composite materials
- Will be presented magnetic composite materials with particular properties, tailored to specific applications in various fields such as medicine, bio detection, catalysis, agriculture and environment
- The audience will be introduced to the thermal decomposition method of MNPs synthesis with different shapes and sizes and the transformation of MNPs from hydrophobic to hydrophilic phas
- Different functionalization methods of MNPs specific to the targeted applications will be presented
