The role of different architectures of Nanoscale constructs and the relationship to their biological impacts

The high purity after biological separation from complex biological fluid is one of the highest challenges in the biomedical research, which prohibits the identification of the key biomolecules, vesicles, or other entities, thus limit the progress in better understanding of bio-nano interaction due to the presence of contamination of impurities, as described in the review of biological separation in Chapter I, the conventional method are destructive to the purified samples, time and effort-consuming in experiment practical, low in biological specificity or poor in compatibility towards the downstream analysis. Among all the unique properties owned by material at nanoscale, super-paramagnetic property has caught attention that the magnetic nanoparticles are a promising tool for biological separation with high purity, in this thesis three main variants of Iron Oxide nanoparticles with super-paramagnetic property were developed and investigated on their application and the impact to the biomedical research.
Previously a multifunctional Iron Oxide nanoparticles with a fluorescent dye incorporated silica shell was designed and applied in the isolation of the vesicles for the cell lysate representing the intercellular trafficking of the nanoparticles, and the single vesicle analysis by flow cytometry, in Chapter II, the optimization of the parameters in the synthetic methodologies of such fluorescent silica encapsulated Iron Oxide nanoparticles was studied, for repeatable upscaling with consistent quality, validated by a variety of characterisation techniques, in-vivo experiment was performed as the extended application of the upscaled nanoparticles, where the bioaccumulation of the nanoparticle was discovered via in-vivo imaging over the individual extracted organs after nanoparticle injection.
In Chapter III, a nanoparticle with fast magnetic extraction efficiency was designed using the optimized parameters reported in Chapter II, as a platform allowing surface functionalization, for developing the molecular detection tool for Point-Of-Care test kit, the nano conjugated PNA (Polypeptide Nucleic Acid), A preliminary trial gave that the PNA was successfully conjugated on the PEGylated nanoparticles via click reaction (copper-free Strain Promoted Azide Alkyne Cycloaddition), the nano conjugated PNA was found with retained function in capturing target molecules with high specificity within short time, thus it may potentially support the high performance of Point-Of-Care test.
In Chapter IV, a ultrasmall Magnetic Dot was designed as a promising magnetic isolation tool, with high diffusion rate, favouring the fast target seeking among complex biofluid, the unique architecture of one single antibody-dot conjugate allowing the quantitative mapping of the surface biomarkers on the Extracellular Vesicles was designed for future application in magnetic field flow fractionation, to isolate the subpopulation of the Extracellular Vesicles based on their biological identities. A model of target/off-target was designed using two different protein coronas for the study of the binding kinetics of the antibody conjugated Magnetic Dots, in which the specific binding and magnetic extraction was validated. At last, in a preliminary trial the Extracellular Vesicles sourced from HEK-293 cell line was chosen as the target on which the Magnetic Dot successfully separated a portion of Extracellular Vesicles with abundant amount of EDIL3 biomarkers.
Overall, this thesis presents a progressively comprehensive study on how super-paramagnetic nanoparticle is synthesized with fine control of their physiochemical properties according to their applications as the biological separation especially for the isolation of subpopulation of Extracellular Vesicles, which is vitally important for better understanding of the intercellular communication involved in the mechanism of the cancer metastasis for developing diagnosis and therapy.