The Self-assembly Of Amyloid Polypeptide HIAPP20-29 Was Used As A Template To Construct A Metal Photothermal Antibacterial Material

Amyloid is a class of fibrin that is insoluble in the human environment and mainly composed of β-sheet secondary structure,which is closely related to many degenerative diseases.However,amyloid not only plays a role in the pathogenesis of the disease,but also participates in non-pathological events,and also plays a key role in the biological activities of creatures,eg.the signaling,communication and memory storage.They are essential for maintaining the basic activities of life at normal physiological levels.For example,hormonal proteins,curli proteins,lysozyme,etc,play an irreplaceable role in the biological environment.Amyloid peptides have a good biocompatibility,low immunogenicity and low inflammatory potential.Under most biological conditions,it is stable and furthermore the specific function can be achieved through chemical modification based the amyloid peptides.Therefore,to explore the functional nanomaterials based the self-assembly of amyloid peptides is promising and can be applied in different area,such as biomaterial science and biomedicine,etc.Human islet amyloid 20-29(hIAPP20-29)is considered to be the most critical fragment in the entire sequence,which is responsible for the self-assembling into fibrils.Therefore,in this work,the self-assembled aggregates of hIAPP20-29 were used as the templates to construct the metal functional nanomaterials.Initially,the interaction between the assembled nanostructure of hIAPP20-29 and the liposome was investigated.Furthermore,metal nanofibers based the hIAPP20-29 self-assembled aggregates were prepared and the photothemal antimicrobial activity was evaluated.We have found that hIAPP20-29 self-assembled aggregates can intercalate into the cell membrane layer without affecting the integrity and releasing its contents.We could synthesize the functional metal nanomaterial by one-pot reduction method based the self-assembly of hIAPP20-29 with a good photothermal conversion.The self-assembling fibrils of polypeptide can arrange the metal nanostructure orderly along the surface and also contribute the good affinity of metal nanomaterial to the bacteria that will maximize the efficiency of photothermal ablation of the pathogenic bacteria.The specific research is displayed as follows:(1)The investigation of the binding and interaction mechanism between the self-assembled nanostructure of hIAPP20-29 and the liposome.Neutral,positive charged,negative charged phospholipid vesicles can mimic the bacterial cell membrane as the simple model system.We tried to use quartz crystal microbalance(QCM),atomic force microscopy(AFM),infrared spectroscopy(FI),dynamic light scattering(DLS),fluorescence spectrophotometer(FL),etc.,to explore the interactions and mechanism of peptides and phospholipid membranes from different perspectives.It was found that hIAPP20-29 can interact with the liposome without membrane structure disrupting and releasing the contents in the liposome.We proposed that the peptide aggregates can penetrate into the membrane structure and enable the liposome intact,which implies the good affinity of the assembled nanostructure of hIAPP20-29 with liposome.(2)Based on the findings that hIAPP20-29 aggregates can intercalate into the lipid membrane structure,in this section,we utilized the hIAPP20-29 self-assembly as the template to synthesize the gold/amyloid peptide hybrids,gold nanofibrils with gold nanocubic structure aligning on the fibrils.Compared to the template-free gold nanomaterials,the new synthesized nanomaterials presented the controllable morphology characterized by UV-vis spectra and TEM,good photothermal conversion and excellent photothermal ablation of pathogenic bacteria,such as E.coli,and the photothermal sterilization rate can reach 100% in short time.(3)The silver-fibril nanomaterials were synthesized based the hIAPP20-29 aggregates by reduction method,and the preliminary experiments were carried out.Through the near-infrared irradiation,the new synthesized nanomaterials presented a good photothermal conversion.Furthermore,it can display the good affinity to the bacteria,for instance,E.coli in the case of no irradiation,which will be beneficial for the further application in the photothermal therapy in cancer and pathogenic bacteria infection.