Dual Size-Dependent Effect of Fe3O4 Magnetic Nanoparticles Upon Interaction with Lysozyme Amyloid Fibrils: Disintegration and Adsorption.

Nanomedicine compounds containing nanoparticles, such as iron oxides and gold, have been demonstrated to be effective in promoting different magnitudes of interaction with amyloid ß fibrils, of which disintegrating or inhibiting effects are of great importance to treating fibrillary aggregation-induced neurological disorders such as Alzheimer's disease. This research herein studies the interaction between lysozyme amyloid fibrils, a type of fibers derived from hen egg white lysozyme, and Fe3O4 magnetic nanoparticles (MNPs) of an assorted diameter sizes of 5 nm, 10 nm and 20 nm, using atomic force microscopy (AFM). Specifically, the effects of the sizes of negatively charged MNPs on the resultant amyloid fibrillary mixture was investigated. Our results of AFM images indicated that the interaction between MNPs and the fibrils commences immediately after adding MNPs to the fibril solution, and the actions of such MNPs-doped fibrillary interplay, either integration or segmentation, is strongly dependent on the size and volume concentration of MNPs. In the cases of 5 nm and 20 nm particles of equivalent volume concentration, the adsorption and agglomeration of MNPs onto the fibrillary surfaces was observed, whereas, interestingly, MNPs with diameter size of 10 nm enables segmentation of the slender fibrils into debris when a proper implemented volume concentration was found, which signifies utter destruction of the amyloid fibrillary structure.

Dynamic morphogenesis of dendritic structures formation in hen egg white lysozyme fibrils doped with magnetic nanoparticles.

In this research, the dynamic process of aggregation that forms microflower morphology in solution of lysozyme amyloid fibrils doped with spherical or spindle-like magnetic nanoparticles during the process of drying as well as their final microstructures were investigated. The prepared lysozyme amyloid fibrils as well as their mixtures with in-lab synthesized magnetic particles, which were prepared by adding the nanoparticles to the fibrils solution after the process of fibrillation was done, were characterized using brightfield trans-illumination-mode optical microscope, atomic force microscopy (AFM) and scanning electron microscope (SEM). Brightfield optical imaging bases upon photoabsorptive property of the fibrils-nanoparticle composites clearly reveals the morphological features in microscale, and additionally, for the in vivo, live action of the time-dependent process of self-assembly of such composites composed of fibrillary structure incorporated with magnetic particles was optically elucidated at ambient temperature. Moreover, while results of AFM reveal delicate and peculiar association of fibrils with magnetic nanoparticles of different shapes, SEM images illustrate a stark difference in fine detailed final morphology of microstructures associated with spherical and spindle-like nanoparticles. Our results indicated that the interaction between fibrils solution and the nanoparticles commence right after mixing, the dynamic process of forming dendritic structure resembling microflower morphology is on the order of minutes, and its final structure is highly dependent on the shape of magnetic nanoparticles.