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Project

Synthesis of functional nanoparticles for the quantification of aquatic pathogenic micro-organisms.

The development of multifunctional nanomaterials has proven to be beneficial for many applications. Nanoparticles in particular have been intensively investigated, which resulted in large advances in particle synthesis and control of their properties. From a biomedical point of view, iron oxide nanoparticles are especially valuable thanks to their biocompatibility and low toxicity. Their magnetic properties are already applied in medical imaging, hyperthermia for cancer therapy and advanced drug delivery techniques.

In this dissertation we present the development of multifunctional iron oxide nanoparticles that can be used for the magnetic isolation of bacteria from an aqueous solution, as a pre-concentration technique.

The synthesis and characterization of the core nanoparticle is described in the first part of this work. An enhanced method of surface functionalization was developed, that enabled us to efficiently coat the particles with multiple different ligands. We applied a covalent surface modification method to improve the robustness and long-term stability and storage of the material. The influence of the different ligands on the colloidal stability was investigated, providing a solid base for further development.

In order to provide sufficient colloidal stability to the nanoparticles, a new ligand was designed and synthesized. By modifying a poly(ethylene glycol) chain with two different functional groups, a new heterobifunctional ligand was produced. Thanks to the presence of the water soluble backbone, the functionalized nanoparticles showed excellent stability in various complex environments. Moreover, we covalently coupled antibodies to these particles and confirmed that their activity was retained, which is crucial for their applicability. The synthesis protocol to form these bioconjugated nanoparticles is described in the second part of this work.

Legionella pneumophila bacteria were chosen as the model target for magnetic isolation experiments. These bacteria are known to cause various diseases, including severe types of pneumonia. Consequently their detection is mandatory by law in all public water systems. We investigated by flow cytometry measurements, whether or not the bioconjugated nanoparticles are capable of isolating these bacteria from an aqueous solution. The results indicated that the developed nanoparticles can very efficiently isolate these targeted organisms. Furthermore, we were able to capture L. pneumophila from a mixture of bacteria, which underlines the potential and robustness of the proposed methodology.

The results showed that the new heterobifunctional ligand can efficiently stabilize nanoparticles and allows for subsequent modification with antibodies. We developed a nanoparticle platform for highly efficient magnetic isolation of bacteria in complex environments. By choosing the correct antibodies, a wide range of proteins or organisms can be targeted. This makes the methodology highly valuable for monitoring water quality or for magnetic purifications in complex media.

Date:1 Oct 2010 →  31 Dec 2015
Keywords:Antibodies, Superparamagnetic nanoparticles, Surface, Bio-conjugates
Disciplines:Inorganic chemistry, Organic chemistry, Theoretical and computational chemistry, Other chemical sciences, Physical chemistry, Sustainable chemistry
Project type:PhD project