Studies On Preparation And Character Of Bilirubin Adsorption And Surface-imprinting Materials With High-performance

Bilirubin is a principal degradation product of heme catabolisma. High bilirubin concentration may cause obstructive jaundice, and further may results in acute renal failure. At the same time, serum bilirubin is an important index for judging the liver's functions and identifying a variety of liver diseases. Therefore, the removal of high concentrations bilirubin and detection of bilirubin level are particularly important. In this study, based on the molecular design of materials, two kinds of functional materials with good adsorption properties for bilirubin and two kinds of bilirubin surface molecular imprinted polymers were prepared. And these materials were hoped to be applied in the removal of high concentrations of bilirubin (Hemoperfusion adsorbents) and testing (building of chemical sensors), respectively.First, the crosslinking microbeads CPGMA with controllable size were synthesized by suspension polymerization of glycidyl methacrylate (GMA) and ethylene glycol dimethylacrylate (EGDMA). The effects of various factors, such as disperser PVA weight percentage(wt%), agitating rate, the ratio of oil phase to water phase, the weight percentage(wt%) of EGDMA and NaCl, on the sphericity and diameter of the microbeads were examined. The experimental results show that the sphericity of crosslinking microsbeads CPGMA is excellent and various factors the above-mentioned can all influence the particle diameter. And the optimal condition for prepareing CPGMA microsbeads with diameter about 100μm is determined.The crosslinking microspheres of CPGMA were modified chemically with aminating agents, hexanediamine and three kinds of multi-ethylene multi-amine. The effects of various factors, such as the chemical structures of the aminating agents, pH values of the medium, ionic strength and temperature, on the adsorption property of the functional microsphers for bilirubin were examined. The adsorption mechanism of the aminated microspheres towards bilirubin was studied more in depth. The experimental results show that the aminated microspheres has strong adsorption ability for bilirubin and the adsorption capacity can reach 17.8mg/g. Between the aminated microspheres and bilirubin molecules, electrostatic interaction is dominative, meanwhile, there are hydrogen bonding and hydrophobic interaction. As pH=6, the electrostatic interaction is the strongest, leading to the highest adsorption capacity. Higher ionic strength is disadvantageous to the electrostatic interaction, and the increasing of salinity conduces to the decreasing of the adsorption capacity. The rising of temperature is advantageous to the hydrophobic interaction, whereas is unfavorable to hydrogen bonding, and the predominated one between them dominates the effect of temperature on the adsorption capacity. The adsorption ability of the aminated microspheres modified with hexanediamine is stronger than that modified with multi-ethylene multi-amine owing to strengthening the hydrophobic interaction and smaller steric hindrance which comes from longer spacer.Polyethylenimine (PEI) was grafted on the surface of the CPGMA in the couple graft manner via the ring-opening reaction between the epoxy groups and the amino groups, and grafting microsphere PEI-CPGMA was obtained. The adsorption property of PEI-CPGMA for bilirubin was mainly studied, and the effects of various factors, such as pH value, ionic strength of the medium and the grafting degree of PEI, on the adsorption property were examined. The static adsorption experiment results show that PEI-CPGMA has a strong adsorption action towards bilirubin. The pH value of the aqueous solution has great effect on the adsorption property of PEI-CPGMA. In near neutral solution (pH=6), there is maximum adsorption amount. The ionic strength of the medium exhibits little influence on the adsorption property of PEI-CPGMA. The higher the grafting degree of PEI on the microsphere surface, the stronger the adsorption capacity.PMAA was grafted onto the surface of silica gel particles via the coupling effect of MPS, and the grafting particle PMAA/SiO₂ was prepared. Then, using novel molecular surface imprinted technique, the molecular imprinted polymethylacrylic acid on the surface of silica gel, MIP-PMAA/SiO₂, was prepared with bilirubin as a template molecule and EGDE as crosslinking agent. Both static and dynamic methods were adopted to study the binding properties of MIP-PMAA/SiO₂ for bilirubin. The experiment results show that MIP-PMAA/SiO₂ have higher selectivity ability and excellent combination property for bilirubin. Besides, MIP-PMAA/SiO₂ has excellent elution property, with the mixed solvent of EDTA and NaOH as the eluent, the desorption ratios of bilirubin reach 99.48 % in 10 bed volumes.Polyethyleneimine (PEI) was grafted onto the surface of silica gel particles via the coupling effect of CP, and the grafted particle PEI/SiO₂ was prepared. Then, the molecular imprint polyethyleneimine on the surface of silica gel, MIP-PEI/SiO₂, was prepared with bilirubin as a template molecule and EGDE as crosslinking agent by using novel molecular surface imprinting technique. Both static and dynamic methods were adopted to study the identification properties of MIP-PEI/SiO₂ for bilirubin. The experimental results show that MIP-PEI/SiO₂ has higher selectivity ability and excellent combination property for bilirubin. Besides, MIP-PEI/SiO₂ has excellent elution property, with the mixed solvent of EDTA and NaOH as the eluent, the desorption ratios of bilirubin reach 99.39% in 11 bed volumes.