Preparation Of BSA Molecule Surface-imprinted Materials And Study On Its Macromolecule Recognition Character

Albumin is the most abundant and important protein in plasma, which not only has the function of maintaining the plasma colloid osmotic pressure, but also has the function of storing and transporting the endogenous metabolites and the exogenous drug molecules. Albumin is a kind of important carrier protein which is involved in many important life processes, and is also one of the largest pharmaceutical proteins in clinical use. At present, albumin in the clinical use is still purified from human plasma known as human serum albumin(HSA). Recombinant albumin by genetic engineering to produce has attracted much attention. Therefore, it is urgent to develop a new separation and purification technology and separation materials in the production of albumin through plasma purification or through genetic engineering. In various kinds of separation and purification materials, molecular imprinting polymer materials called as artificial antibodies or artificial receptors have been widely studied and applied because of its specific recognition selectivity. It is a potential application of molecular imprinting technique to identify the template molecules in protein separation and purification. However, the molecular imprinting technique in aqueous solutions is still a very challenging research field.In this study, with micron sized silica gel particles and polymer microspheres as matrix, cationic monomer acryloxyethyltrimethyl ammonium chloride(DAC) and dimethylaminoethyl methacrylate(DMAEMA) as functional monomer, two kinds of BAS surface molecular imprinted polymers are smoothly prepared by using new surface molecular imprinting techniques “grafting polymerization synchronized with imprinting” and “pre-graft polymerizing and post-imprinting” in a aqueous solution. In the imprinting processes, the strong electrostatic interaction between the host-guest molecules is the foundation. Furthermore, the macromolecule recognition characters and mechanisms of MIPs for BAS are examined in depth. At the same time, the cationic grafted particles with brush structure are prepared, and the adsorption properties and mechanism of BSA are investigated.First, the interaction between the cationic monomer DAC and BSA are examined by UV absorption spectrum and fluorescence emission spectrum, and the influence of p H value of the medium on the interaction was also investigated. Micron-sized silica gel particles are surface modified with coupling agent γ-Aminopropyltrimethoxysilane(AMPS). This practice realizes the surface-initiated graft-polymerization with the initiation systems of-NH2/S2O82- in a solution and the grafted particles PDAC/Si O2 were prepared, and the interaction between the grafted macromolecule PDAC and BSA is also investigated in depth. The research results show that in aqueous solutions, a host-guest complex of DAC and BSA is formed,which lays a foundation for the use of "grafting polymerization synchronized with imprinting" surface molecular imprinting technique in the water medium. By right of t electrostatic interaction, the grafted particles PDAC/Si O2 produce strong adsorption ability for BSA.Subsequently, the crosslinked polyvinyl alcohol microspheres(CPVA) are made by direct crosslinking method in the suspension system. With methyl cryloyl chloride(MAO) as reagent, and a great deal of polymerizable double bonds are introduced onto the surfaces of the microspheres, forming modified microspheres MA-CPVA. In aqueous solution, with a strong electrostatic interaction, the template BSA molecules are surrounded by the monomer DAC. With MA-CPVA as matrix and with cationic monomer DAC as functional monomer as well as with crosslinker N, N’-methylene bisacrylamide(MBA) as crosslinker, BAS surface-imprinted material MIP-PDAC/CPVA is smoothly prepared by the initiation of ammonium persulphate. The adsorption and recognition characteristics of MIP-PDAC/CPVA for BSA are studied in depth. The experimental results show that MIP-PDAC/CPVA possesses high adsorption capacity for BSA, and reaches to 108 mg/g. More importantly, MIP-PDAC/CPVA possesses excellent specific recognition to BSA. The selectivity coefficients relative to BHb are 60.2.As before, the interaction between the monomer DMAEMA and BSA is examined by UV absorption spectrum and fluorescence emission spectrum. Through the initiation systems of-NH2/S2O82-, the graft polymerization of DMAEMA is carried out on the surface of modified silica particles, preparing the grafted polymer PDMAEMA/Si O2, and the interaction between the grafted polymer PDMAEMA/Si O2 and BSA is also investigated in depth. The research results show that in aqueous solutions, a host-guest complex of DMAEMA and BSA is formed by the electrostatic interaction and hydrogen bonding. By the driving forces from electrostatic interaction and hydrogen bonding, the grafted particles PDMAEMA/Si O2 produce strong adsorption ability for BSA, which lays a foundation for the use of " pre-graft polymerizing and post-imprinting " surface molecular imprinting technique in the water medium.In aqueous solution, by the driving forces from electrostatic interaction and hydrogen bonding between PDMAEMA/Si O2 and BSA, the grafted particles PDMAEMA/Si O2 are adsorbed saturated by BSA. With dibromohexane as crosslinking agent, marcromolecular PDMAEMA/Si O2 are cross-linked and the BSA molecular is embedded in the cross-linked network, obtaining BSA molecular imprinted polymers MIP-PDMAEMA/Si O2. The experimental results show that MIP-PDMAEMA/Si O2 possesses very high adsorption capacity for BSA, and reaches to 89.8 mg/g. Compared to the BHb, the selectivity coefficients relative are 42.4.Lastly, on the basis of the fabrication of the grafted polymer PDMAEMA/Si O2, the tertiary amine groups in the chains of the grafted macromolecule PDMAEMA are quaternized with chlorethamin as reagent, obtaining the functional grafted particles QPDMAEMA/Si O2, on which cationic polyelectrolyte macromolecules QPDMAEMA, are grafted. The isothermal adsorption experiments are carried out, and the effects of several main factors including p H value of the medium, salinity and temperature on the adsorption performance of QPDMAEMA/Si O2 particles are examined. The adsorption thermodynamics is studied. The experimental results display that QPDMAEMA/Si O2 particles produce very strong adsorption towards BSA by driving of electrostatic interaction. With the increase of p H value, the adsorptivity first increases and then decreases, and it reaches the maximum adsorption capacity of 112 mg/g as the p H value of the medium is equal to p I of BSA. On both sides of the isoelectric point, the effects of salinity on the adsorption capacity are opposite. As the p H value of the medium is equal to the isoelectric point of BSA, the adsorption capacity nearly does not change with the salinity. The adsorption is exothermic and during this process the entropy value decreases. The adsorption process is driven by enthalpy.