Preparation And Proerties Of Block Copolypeptide Brushes And Study On Gold Nanoparticle-coating Polypeptide

Amphiphilic polypeptides are important biomimetic materials used in drug delivery, tissue engineering, and genophore due to their unique amphiphilic properties like nature phosphatide, special ability to fold into regular secondary structures such as the a-helix and P-sheet, various self-assembled morphologies and biocompatibility as well as biodegradability. The amphiphilicity of polypeptides origins from hydrophilic and hydrophobic groups, which can be located at both ends and both sides of backbone even more cross arrangement of polypeptide. To take control of their performances and further excavate practical applications, it is necessary to design and synthesize polypeptides with different chemical structures. Here, a series of amphiphilic polypeptides such as polymer-brush and amphiphilic copolymer were designed and synthesized, and their thermos-responsive properties were researched, the properties of the gold nanoparticle-coating polypeptide were explored. The main contents are as follows:(1) A combination of ROP polymerization and click chemistry were used to prepare copolypeptide brushes (PBLG-b-PCELG-g-G) with different PBLG segment length, in which OEG dendrimers were introduced into polypeptide as an hydrophilic group and triggered thermos-ability. The effects of polypeptide structure and molecular weight on the self-assemble and thermo-responsive properties were studied in details. The mechanism of thermo-responsive properties was explained through the self-assemble kinetics and thermodynamic process of aqueous solution.(2) A polypeptide of PBLG with an individual OEG dendrimer G2 in the chain end and a thioctic acid containing disulfide bond in other end was synthesized via similar route. Gold nanoparticles (GNPs) with a core diameter of 30nm were synthesized using trisodium citrate as surfactant in aqueous phase. The gold nanoparticles capped with polypeptides were synthesized by ligand-exchange method, and characterized by UV-Vis, DLS and TEM. In addition, the package of small hydrophobic molecule to mimic encapsulation of hydrophobic drug and the phase transfer behavior were also studied and, it is found that the gold nanoparticles coated with polypeptide show a more rapid and simple procedure of phase transfer from aqueous to organic phase.