Effect Of Nano-SAMs Interface For Aβ Aggregation

Micro-nanoparticles have abilities to regulate amyloid aggregation.Matureβamyloid fibrils have a range of morphological transformings during their formating stages,from monomers to Aβoligomers,then mature fibers which are difficult to dissolve.The cytotoxicity associated with amyloid deposits is not only caused by soluble mature fibers,but also by other fibril forms of proteins during their formation processes,and may even be together of them.Different protein aggregating forms have different potential molecular structures,which may be controlled by changing the fibril growth conditions and regulating the properties of the interface.Identifing the sense of amyloid assembly morphology and the toxicity of different morphological proteins are very important for identifing the pathogenic mechanism of many amyloid diseases.Apart from the surface chemistry that affects the Aβaggregation,protein are also inevitably affected by solution conditions.The connection of various micro-nano particles and the effect of interfacial chemistry on Aβfibrosis is the core idea of this thesis.In this paper,a novel method for the construction of artificial ultra-thin self-assembled membranes“mixed-solvent precipitation”was designed.The method is based on the principle of solubility difference of ultra-micro nanoparticles in various solvents and the“minimum energy principle”,using tiny nanoparticles(including:gold nanoclusters and quantum dots such as C₇H₁₃NO₃S-AuNPs,β-HgS@ZnS QDs).Nano-SAMs with dense two-dimensional structure was fabricated by slowly depositing nanoparticles（dissolved in a good solvent）onto a substrate by slowly adding of bad solvent（acetone）in a mixed solvent（organic solvent and water）.The mixed solvent precipitation method solves two difficulties in the traditional SAMs fabrication method:how to make Nano-SAMs with high density in a short time;how to construct Nano-SAMs with ordered two-dimensional surface structure.By using the new method,several micro-nano particles which have significant inhibition effects for Aβprotein,and several interfaces with different surface chemistries,were combined together.We assembled the nanoparticles onto some interfaces and studied the effects of those micro-nano interfaces on the aggregation morphology of Aβprotein.During that time,we also observed the effects of Aβaggregation on different interfaces without nanoparticles,and also Aβaggregation with different Aβculture environments（or Aβgrowth environments）such as pH and buffer types.From the research works,we found the competition between"Aβmonomer and interface interaction"and"H₂O and interface interaction"controls the aggregation,assembly behavior and morphology of Aβat the interface.It means,specifically,the synergy between hydrophobic interactions（related to molecular polarity）and intermolecular interactions（including strong interactions drove by electrostatic forces,and weak interactions represented by van der Waals forces）.And when the structured interface has strong adsorption on Aβmolecule,the further growth of Aβwas stopped,from the oligomer to the mature protein fibril.This thesis lists and explains the different assembly and aggregation morphologies of Aβprotein at different interfaces.Besides,it also provides a possible intrinsic mechanism for the inhibition of micro-nanoparticles（such as gold nanoclusters and quantum dots）on Aβprotein aggregation.