Preparation Of Creatinine-Adsorbing Materials With High Performce And Study On Their Adsorption Chayacter

After cardiovascular disease, tumor and diabete, at present, the renal main functionprogressive irreversible decline caused by various kidney diseases, namely chronic renalfailure, has become a great nuisance that has serious threat to human health in the world, andit will transform into uremia as the liver loses its ability completely. The kidney plays animportant rule in the body’s metabolism. The toxic sunstances including creatinine will beaccumulated extensively in human blood of kidney disease patients owing to kidney functiondecrease and kidney failure, and it seriously threaten patient’s life. The excess creatinine notonly will cause a range of symptoms of poisoning, but also it will accelerate the process ofkidney failure. Therefore, it is very significant to effectively remove the excess creatinine inhuman blood of kidney disease patients. Consequently, it has important science significancein medical research area to research and prepare creatinine-adsobting materials with highperformance and to remove the creatinine accumulated in the body of kidney disease patientsby using blood purification techniquessuch as perfusion technique.In this work, via elaborate molecular designing, crosslinking polyvinyl alcohol （CPVA）microspheres that have biocompatibility were used as the starting substance, and two graftedmicrospheres that have strong adsorption ability for creatinine were successfully prepared. Aredox initiating system was consisted of the hydroxyl groups on CPVA microspheres and theceric salt in the solution, and the two functional monomers, methacrylic acid （MAA） andsodium styrene sulfonate （SSS）, were graft-polymerized onto CPVA microspheres throughsurface-initiated graft-polymerization method, respectively, resulting in two graftedmicrospheres, CPVA-g-PMAA and CPVA-g-PSSS. Besides, a creatinine molecule-imprintedmaterial MIP-PSSS/CPVA, which has special molecular recognition selectivity and excellentbinding affinity for creatinine, was also prepared with SSS as the functional monomer and creatinine as template and by using a novel molecular surface-impriting technique. Theadsorption characters and mechanisms of the above three medical macromolecular materialtowards creatinine were investigated in depth, and the satisfactory study results were achived.These materials are promising in the blood purification application.Crosslinked polyvinyl alcohol （CPVA） microspheres were first prepared by usingdirectly crosslinking-balling method in a suspension system and with glutaraldehyde ascrosslinking agent. On that basis, a redox initiation system was constructed with a great dealof hydroxyl group on CPVA microspheres and cerium ammonium sulfate, and thesurface-initiated graft polymerization of methacrylic acid （MAA） was performed in anaqueous solution, resulting in the grafted microspheres CPVA-g-PMAA. The chemicalstructure and physicochemistry characters were adequately characterized with infraredspectrum （FTIR）, scanning electron microscope （SEM） and zeta potential determination.Theeffects of the main factors on the graft polymerization were examined, and the mechanism ofthe graft-polymerization was explored, and the conditions of the graft-polymerization wereoptimized. The experimental results show that hydroxyl group-cerium salt redox initiationsystem can effectively initiates the graft polymerization of MAA on CPVA microspheresunder the suitable conditions such as at45℃, at a cerium salt concentration of4.9×10-3mol·L^-1, at a sulfuric acid concentration of0.17mol·L^-1and at a MAA concentration of0.55mol·L^-1, and the grafted microspheres CPVA-g-PMAA with a PMAA grafting degree of30g/100g can be prepared.Then the adsorption property of the grafted microspheres CPVA-g-PMAA for creatininewas examined in more detail, and the adsorption mechanism and thermodynamics werestudied. The experimental results show that there exist strong interactions, electrostaticinteraction （main action force） and hydrogen bonding （a supporting role） between the graftedmicrospheres CPVA-g-PMAA and creatinine molecule, and it lead to that the graftedmicrospheres display very strong adsorption ability towards creatinine. As pH=8.0, theadsorption capacity has a maximum value,40mg·g^-1. The adsorption process is exothermic,and it is driven by enthalpy. The presence of electrolyte in the solution affects negatively the adsorption property of the grafted microspheres CPVA-g-PMAA, and the adsorption capacitydecreases with the increase of the ion concentration.In this work, another kinds of grafted microspheres, CPVA-g-PSSS, were also preparedwith the surface-initiated graft-polymerization method and with SSS monomer. The chemicalstructure, morphology character and the surface electrical property of the graftedmicrospheres CPVA-g-PSSS were characterized by using several means such as FTIR, SEMand zeta potential determination. The adsorption ability, mechanism and adsorption of thegrafted microspheres CPVA-g-PSSS for creatinine were also examined and reseached indepth. The study results show that under the suitable conditions the grafted microspheresCPVA-g-PSSS with a grafting degree of16g/100g can be smoothfully prepared. By right ofthe strong electrostatic interaction between the sulfonate groups of the grafted microspheresCPVA-g-PSSS and creatinine molecule, the microspheres CPVA-g-PSSS can produce verystrong adsorption ability. The adsorption capacity is pH-dependent, and the greater theadsorption capacity, the lower the pH value. At pH=1, the adsorption capacity can reach15.65mg·g^-1. The adsorption of the microspheres CPVA-g-PSSS for creatinine is also anexothermic process, and this process is also drived by enthalpy.Finally, based on “surface-initiated graft-polymerization”, in an aqueous solution system,creatinine molecule-surface imprinting was conducted with SSS as monomer and N,N’-methylene-bis-acrylamide （MBA） as crosslingking agent by using hydroxyl-ceric saltredox ionitiating system and SSS, and the imprinted microspheres MIP-PSSS/CPVA wereobtained. With N-hydroxysuccinimide （N-Hy） and creatine （Cr） as two contrast substances,the recognition character and binding property of the creatinine molecule-surface imprintedmaterial MIP-PSSS/CPVA for creatinine were researched detailedly. The selectivitycoefficients of MIP-PSSS/CPVA for creatinine relative to the contrast substances, N-Hy andCr, are5.51and6.60, respectively, displaying high recognition selectivity.