Study On The Modification And Physicochemical Properties Of α-zein

Zein, its excellent biodegradability, biocompatibility, and security features were widely used in biopharmaceutical, health caring, textile fibers and other fields as renewable plant materials because of their easy to chemical and physical modifications, it has always been the research focus of scientists. Zeins were characterized by their high hydrophobicity and classified into four groups: α, β, γ and δ-zein, depending on their solubility, molecular weight, and structure, previous studies have focused on the hybrid protein containing four components(α, β, γ and δ-zein), but the solubility and stability of this hybrid protein was inadequate. Recent years, it was found that the purified α-component was provided with special properties, particularly suitable for starting materials as pharmaceutical carriers and tissue engineering scaffolds. In this thesis, α-zein was selected to develop new potential applications in the biomedical field as a starting material to purified, modifidied, and to design carrier of anticancer drugs and gene vector could be used to carry drugs and DNA overcome tumor resistance. The main conclusions of this study are as follows:Methoxy polyethylene glycol(mPEG) grafted α-zein protein(mPEG-g-α-zein) was synthesized as a new kind of copolymer micelle drug delivery system in the first part. Micelles morphology observed by SEM and AFM, the particle size of micelles was about 90 nm. The in vitro drug release profile showed a zero-order release of curcumin, the cytotoxicity of the polymer was low, the copolymer concentration was increased to 1mg/m L, the cell survival rate was greater than 80%. Consequently, the mPEG-g-α-zein micelles could be used as a potential drugs nano-carrier and colloidal dispersions.A kind of p H-responsive gene and drug co-delivery carriers PDMA-g-α-zein was synthesized in the second part of this work. Copolymer as a new non-viral vector for gene and drug released carrier in vitro was studied. ZM5 K series polymer and DNA retained a better DNA condensation capability complex ratio at 0.5:1. Zero-order release kinetics in vitro indicated that the drug loaded complexes achieve long cycle as carrier. The concentration of serum added from 5% to 20%, transfection results showed that the majority of cells stably expressing green fluorescent protein in the serum, transfection efficiency were better than bPEI. PDMA-g-α-zein were pH-responsive drug and gene co-delivery carriers, which could protect DNA from degradation effectively.A new kind of mPEG-g-α-zein/PDMA-g-α-zein mixed micelles gene transfection vector with low toxicity were prepared in the third part of this work. This method reduces the charge on the PDMA micelles, zeta potential was decreased, mPEG segment could reduce carrier cytotoxicity effectively. Study on the binding ability of micelles and DNA, as the mixing ratio increased to 80% and 90%, compound and plasmid(w/w) ratio at 5:1 caused strong interaction, which could protect DNA from degradation effectively. The cell viability of both samples(80 mg) was higher than 80%, biocompatibility was improved. So, the mixed micelles of mPEG-g-α-zein/ PDMA-g-α-zein were provided with low toxicity and high transfection efficiency, which provided a cationic protein carrier besides virus type and bPEI in the field of gene transfection.This thesis chooses α-zein as based materials, to explore the relationship between structure and properties of protein for novel drug and gene vectors by several methods, which provided technical bases for novel protein carrier preparation and clinical application in the field of biomedicine.