| Self-assembled peptide nanomaterials play an important role in many fields such as biosensors,phototherapy,bioimaging,and drug delivery because of their high biocompatibility,good biodegradability,and controllable structure and function.Peptide molecules can self-assemble into various dimensions of nanomaterials through sequence design,internal interactions,and external conditions,includeing zero-dimensional(0D)nanoparticles,one-dimensional(1D)nanofibers/nanotubes,two-dimensional(2D)nanosheets/nanoribbons,and three-dimensional(3D)hydrogels.Among them,2D peptide nanomaterials with ultra-thin structure,high specific surface area,and rich surface-active sites have attracted more and more attention.However,it is difficult to synthesize 2D peptide nanomaterials because the growth of peptide molecules on the lateral and long axis is hard to control,and therefore how to synthesize stable 2D peptide nanomaterials is still a challenge.This thesis focuses on the self-assembly synthesis of 2D peptide nanomaterials to meet the expected requirements by regulating the external stimulation conditions.Other functional nanomaterials were combined with 2D peptide nanomaterials through covalent/non-covalent interactions to realize the application of peptide nanocomposites in the field of tumor diagnosis and treatment.The main results of this paper are summarized as two aspects.(i)The study of peptide self-assembly affected by external conditions is of great significance for the design and synthesis of peptide nanomaterials with controllable structure and function.In the first study of this thesis,we investigated the self-assembly behavior of the heptapeptide GNNQQNY from yeast prion protein on the interface of inorganic materials.GNNQQNY peptides have been proved to be self-assembled into nanofibers or nanocrystals in the past.In our experiments,it was found that they formed ordered nanofibers/nanoribbons on the surface of mica and highly oriented pyrolytic graphite(HOPG).The effects of solvent effect,molecular concentration,p H value,and evaporation time on the self-assembly behavior of peptides were studies.By adjusting and optimizing the experimental parameters,2D peptide nanoribbons can be effectively generated on the surface of mica and HOPG.On this basis,the self-assembly mechanisms of peptide nanoribbons on the interface between the two materials were discussed.The results of this study can provide inspiration for the design of motif-specific peptides with high affinity and provide guidance for the green synthesis of peptide-based biomaterials with unique functions and application potential.(ii)In the previous work,the self-assembly of peptide nanomaterials affected by external stimulation and its mechanism has been studied,which is helpful for us to further develop the design,synthesis,and applications of peptide nanomaterials.In the second study of this thesis,2D peptide nanosheets were synthesized by adjusting the self-assembly conditions and loading polyethylene glycol-modified gold nanorods.The results showed that the prepared peptide nanosheet composites have good photothermal conversion ability and photothermal stability under 808 nm near-infrared laser irradiation.Meanwhile,the designed peptide nanosheet composites showed high biocompatibility and low biotoxicity in vivo and in vitro.In general,peptide nanosheet composites exhibited good biosafety,tumor cell killing effect,and tumor therapeutic effect in vitro and in vivo.Green synthesis of functional composites based on 2D peptide nanomaterials provides a flexible and reliable strategy for the construction of functional materials for non-invasive tumor photothermal therapy.As a new type of near-infrared laser-induced photothermal reagent,the synthesized peptide nanosheet composites could be potentially used for tumor therapy in vivo and in vitro. |
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