| Traditional complex are usually prepared using synthetic polymer materials,however, such materials are costly, toxic, and time consuming. Compared with traditional delivery systems, self-assembly-based natural biopolymer complex are green and non-toxic, renewable, biocompatible, biodegradable, high loading, high stability, and could controlled release, etc. Apart from this, rich functional groups on the surface of polymer can be modified by targeted groups achieving environmental responsiveness. Natural biopolymer has been widely applied in area of slow release and tissue engineering. With the further development of modern biotechnology, it will present a brighter future. Natural bipolymer mainly referred to protein and polysaccharide. As the material to prepare complex, bovine serum albumin(BSA) is a kind of non-toxic and biodegradable model protein, which has low antigenicity and allergic reactions and can be well decomposed and absorbed by human body, as well as can interact with various drugs. However it is weak in environmental stability and drug loading. Maillard Reaction was found to have the ability to improve the solubility, emulsifiability, anti-oxidation ability, anti-bacterial ability, and thermal stability of proteins, as well as the function to decrease immunogen. Salidroside shows extensive pharmacological and healthy effects such as anti-inflammatory,anti-aging, neuroprotective ability etc. At the same time it also plays a prominent effect in various aspects like suppressing leukemia, gastric cancer, parotid cancer,colon cancer and others. However those were limited for its short biological halfcycle and low oral bioavailability. Studies have reported the usage of liposomes and microparticles to encapsule salidroside, but those organic carriers had shortcomings like instability in vitro and vivo, weak controllability of drug release, leakage, low security and so on. The paper launched a research on preparation and mechanism of BSA modified with re-used waste resource citrus peel pectin CPP. And salidroside and vitamin C, which has been widely used in food, medicine, cosmetics industry while is sensitive to environmental change, were selected to simulated the process ofrelease. The main results are as follows:1. The significant influence on the diameter of BCC was discussed by three factors like mass ratio(MR) of pectin and BSA, protein concentration, and pH at three level in the process of preparation. It's found that particle size of protein mixed with pectin system and the ratio of the two materials, protein concentration, pH value were in response to a certain equation, MR, pH, c, MR × pH, pH × c, pH2, c2 as the significant factor, especially pH, MR as the most significant impact factor. However,response surface equation of BCC got lack of fit. And mixed and gel phase in preparation was studied from the conformational level. It was found that the gel phase made a significant difference from mixed phase.2. The impact of pH condition on secondary structure, morphology and rheological properties of BCC was under discussed. The formation mechanism of BCC was also inferred through determination of above properties. At last, the release in vitro was simulated with salidroside as the model. The results showed that, BSA w,would carried negative charge instead of positive charge when pH was adjusted below the isoelectric point(pI) of BSA(4.7). As anion polysaccharide CPP, the two biopolymers would change from carrying the same kind of negative charge into opposite kind of charge, which strengthened the electrostatic interaction between them and significantly reduced the particle size of complex. The electrostatic and covalent interaction between BSA and CPP was the main formation mechanism of BCC. And it formed a stable and solid three-dimensional network structure with a narrow size distribution(polydispersity index, PDI < 0.06). The result indicated that BCC had high encapsulation efficiency(EE, about 50%) and released slow under simulated gastric and intestinal fluid condition with salidroside as the model molecule, which showed that this novel complex might be a potential deliver carrier for salidroside or other functional food agents.3. The effect of different MR on the preparation of BCC was also under research.The three-dimensional complex with small particle size and stable rheological and conformational properties was obtained at the mass ratio of CPP and BSA 0.5; while MR at 0.2 or 0.8, the system had the trend of self-assembly among protein or multiple-assembly for the lack or excess of CPP. BCC was used as a delivery systemto load the functional agent of vitamin C(Vc). The release mechanism of Vc from BCC was also investigated. Results suggested that the encapsulation efficiency of Vc into BCC was 65.31%. Diffusion, swelling and erosion were co-existed as the main release mechanism of Vc from BCC. BCC remained stable physical and chemical properties with an enhanced Vc retention(73.95%) after 10-week storage. Thus,BCC, which owned excellent network structure, might be a potential delivery system to improve the stability and bioavailability of functional agents in both food and non-food fields. |
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