Synthesis Of N-Substituted Polyacrylamide Resins And Their Adsorption Property For LDL

A safe and efficient therapy approach, so called LDL apheresis, which based on that polyanions covalently bound to porous polymer matrix can selectively adsorb low density lipoproteins (LDL) and very low density lipoproteins from human plasma, has been established for treating patients with severe hypercholesterolaemia or homozygous familial hypercholesterolaemia (FH). Despite the preparation methods and efficiency of various newly developed synthesized polyanion adsorbents for LDL apheresis have been extensively studied and reported, systematical reseajch results of the effects of porous polymeric matrix structures, the types of functional group, the amount and distribution patterns of the functional groups on the adsorption properties of polyanion adsorbents are rarely reported.Macroporous crosslinked poly(methylacrylate-co-triallyisocyanuate) was synthesized by conventional suspension approach. Spherical macroporous N-substituted polyacrylamide was prepared via aminolysis reaction of the polyacrylate with aminolysis reagents, i.e. ethylenediamine, diethylenetriamine, triethylenetetramine and tetra-ethylenepentamine. A serious of polyanion adsorbents, bearingf.different acidic groups as functional groups, were synthesized by reacting with bromacetic acid, chloroacetic acid, phosphorous acid, and chlorosulfonic acid on spherical macroporous N-substituted polyacrylamide supporters. The influence rules of porous polymeric structures, the properties of functional groups and the amount of functional groups on the adsorption properties of the polyanion adsorbents were investigated in this work. The following conclusions were experimentally confirmed:(1) The adsorption selectivity of concerned polyanion adsorbents for low density lipoproteins from human plasma decreases with the increase in crosslinking degree of the polymeric matrix. (2) Stronger acidity of the functional groups is, the higher adsorption capacity andadsorption selectivity for LDL of the polyanion adsorbent will be. (3) To increase the amount and density of the functional groups on the adsorbent surface is beneficial to improve the LDL adsorption capacity and selectivity of polyanion adsorbent. (4) The static interaction of negative charged functional groups on the adsorbents surface with the positive charged domains on LDL particle plays a dominant role in the binding of polyanion adsorbents with LDL.The blood compatibility of the polyanion adsorbents based on macroporous crosslinked polyacrylamide was preliminary explored as well. The bare matrix of macroporous polyacrylamide showed to be compatible well with blood. Functionalization of the matrix lowered the blood compatibility of the adsorbents at somewhat extent although blood compatibility of the functionalized adsorbents remained to be tolerable.Three different polymeric adsorbents, hypercrosslinked poly (divinylbenzene-isocyanuric acid), gel-type crosslinked poly (styrene-isocyanuric acid) and crosslinked poly (N-vinyl acetamide) were prepared in this work as well. The isotherms of tannin adsorption from aqueous solution onto the three adsorbents were measured.The thermodynamical behaviors of tannin adsorption were investigated. Based on Do's model, the isosteric enthalpy was quantitatively correlated with the fractional loading for tannin adsorption on the three polymeric adsorbents. The existence of surface energetic heterogeneities of the concerned polymeric adsorbents was reasonably expatiated. The adsorption mechanism of tannin on the concerned adsorbents was analyzed in detail.