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Carbohydrate coated fluorescent Mesoporous Silica nanoparticles for Biomedical applications

Kirla, Haritha (2019) Carbohydrate coated fluorescent Mesoporous Silica nanoparticles for Biomedical applications. Honours thesis, Murdoch University.

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The human body and many living organisms are comprised of very complex biological system with distinct metabolism. In order to understand life activities, we need to monitor the individual chemical interactions happening in vivo. Bioimaging with naked organic dye molecules always suffers from drawbacks such as photobleaching and biocompatibility issues. Silica matrix protects the fluorophores from external environment and provides hydrophilic shell, which improves the photostability and biocompatibility of dye molecules. A nanocarrier, which is highly compatible with the target metabolic system, may be beneficial for therapeutic and diagnostic applications in living organisms. Mesoporous silica nanoparticles (MSNs) are highly biocompatible and safe for biological applications and may provide the solution.

Therefore, this project focused on the synthesis of dye-doped mesoporous silica nanoparticles, coupling them with various bioactive carbohydrate molecules, and investigation of these nanoparticles for their potential biological applications in microorganisms.

Rhodamine B, fluorescein, and methylene blue dyes were employed for doping into amine modified mesoporous silica matrix through covalent and non-covalent approaches. The results revealed that all dyes were successfully doped into the silica matrix and showed bright fluorescence. In the next stage, methylene blue encapsulated amine grafted mesoporous silica nanoparticles (MB AMSNs) were utilized for coupling with carbohydrates- glucose, maltose, ribose, and raffinose by employing N, N'-carbonyldiimidazole as a coupling agent. The chemical and physical characterization showed the successful conjugation of carbohydrates onto amine-modified silica surface.

Finally, glucose conjugated methylene blue doped mesoporous silica nanoparticles (Glu-MB MSN) were used in bioimaging and toxicity assessments. The as-synthesized nanoparticles were investigated in E.Coli and B.Subtilis bacterial samples. The characteristic results revealed bright fluorescence in bacteria like formations via confocal microscopy. Therefore, Glu-MB MSN may be useful for bioimaging purposes. SEM images showed bacterial aggregation after treatment with nanoparticles. This interaction is relatively higher in the case of B.Subtilis. Moreover, the bacterial cell structure appeared unaltered after incubation with the nanoparticles. This suggested that the nanoparticles were not toxic to these specific bacteria. However, more studies need to be performed to confirm these results.

Item Type: Thesis (Honours)
Murdoch Affiliation(s): Chemistry and Physics
Supervisor(s): Henry, David
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