Preparation Of Cross-linking Agarose And Investigation On Its Application To Bilirubin Adsorption

Agarose gel is a kind of polysaccharide-based matrix which has been ubiquitously used in bioseparation. It is hyrophilicity, porosity, biocompatibility and easy to be modificated. However, agarose gel products nearly are import and very expensive, which blocks the applications of disposable blood purification matrix with agarose gel on clinic. Therefore, based on the works of formers, this paper systematically investigated the preparation of agarose gel microspheres, their cross-linking, screening, and evaluation. Thereafter, a bilirubin adsorbent using agarose gel microsphere as the media, hydroxypropyl (3-cyclodextrin as the ligand, and PEI as the space arm was prepared, and then its adsorption properties on bilirubin was investigated.Reversed phase suspension polymerization was applied to prepare agarose microspheres. The preparation conditions were optimized from the aspects of the component of oil phase, concentration of emulsifier, Hydrophile-Lipophile Balance Number (HLB), mixing speed, and volume of reactor. Then, the cross-linking and screening methods were investigated so as to obtain physichemically stable microsphere with a certain particle size distribution. The results showed that more microspheres with the diameter of near100μm could be obtained when the mixing speed was800rpm, the oil phase consisted liquid paraffin and benzene (v/v:10/1), the concentration of emulsifier was4%, and HLB was7.5.The cross-linked microsphere could be reached the standard of similar products at home and abroad, when the concentrations of epoxy chloropropane and NaOH were0.1mL/mL gel and1.0mol/L, respectively. Agarose gel microspheres were screened by the home-made screen apparatus. The microspheres with the particle size ranging from35to165μm and70%yield were finally obtained.Bilirubin adsorbent was prepared by using epoxy chloropropane-activated agarose gel microspheres as the media, PEI as the space arm, and hydroxypropyl β-cyclodextrin as the ligand. The bilirubin adsorption kinetics and isotherm of the adsorbent were studied. Besides, the effects of the ion strength, temperature, the albumin concentration, and the dynamic adsorption process on the bilirubin adsorption capacity were investigated. The results showed that the maximum adsorption capacity of the adsorbent was2.93mg/mL gel, and the adsorption equilibrium time was1h. In addition, the adsorption isotherm was well described by Freundlich model, and the adsorption constant K was11.05, and n was1.026. The adsorption capacity decreased with increasing the ion strength and albumin concentration but increased with increasing temperature. Dynamic adsorption experiment showed that the adsorption capacity slightly decreased, but that did not affect the practical application.