Studies On The Synthesis Of Polysaccharide Cerium Complexes And The Hydrolysis Activity Of Complexes On Phosphate Bond

China is the most abundant country of rare earth elements(REE),accounting for 80%of the world reserves.With the rapid development of science and technology,the role of REE become more and more important.Rare earth elements and their complexes or compound have been applied in many fields.The rare earth cerium is the most widely used.However,under the neutral physiological conditions,cerium ions can be a cerium hydroxide.The cerium hydroxide is a stable gel precipitation.The application of cerium ions is limited.We need to find a suitable ligand,which can complex with cerium ions to be stable complexes.In order to increase the solubility of cerium at neutral physiological conditions.Thereby expanding the scope of application of rare earth cerium.Since the ionic radius of cerium ions is smaller,the charge and the ionization potential are higher.Therefore the cerium ions has strong binding ability with oxygen.Under the condition of nearly neutral,the cerium ions and the ligand with multiple hydroxyl groups can form stable rare earth complexes.Because the molecular structure of the polysaccharide contains a large number of hydroxyl groups.Therefore,the subject select Ornithogalum caudatum Ait polysaccharide(OCAP),Rhizoma Anemarrhenae polysaccharide(RAP)and Astragalus membranaceus polysaccharide(AMP)as the ligand.These three polysaccharides can complex with cerium ions.We could get Ornithogalum caudatum Ait polysaccharide cerium complexes(OCAP-Ce),Rhizoma Anemarrhenae polysaccharide cerium complexes(RAP-Ce)and Astragalus membranaceus polysaccharide cerium complexes(AMP-Ce).We could use UV,fluorescence spectroscopy and infrared spectroscopy to characterize these three polysaccharide cerium complexes.The method called arsenazo(III)fading spectrophotometric can determine the cerium of the polysaccharide cerium complexes.Finally,researching the hydrolytic activity of these three polysaccharide cerium complexes.The main results are as follows:1.We optimized the preparation conditions of complexes by orthogonal experiments,whose observation index were content of cerium and yield of complexes.The optimum conditions for the preparation of complexes were:REE addition is 0.07%,at 70?,24h,pH 8.2.We used UV and fluorescence spectroscopy to characterize complexes.The results showed that the polysaccharide has been complexed with rare earth cerium;We used infrared spectroscopy to further explore the complexed situation of rare earth cerium and polysaccharide.The results show that Ce(?)and the hydroxyl of polysaccharide have some complexing.3.We have adopted arsenazo(?)fading spectrophotometric to determine the content of cerium.This method has simple operation,high precision and high accuracy.The recovery rate and the stability were determined to meet the requirements.The cerium of OCAP-Ce,AMP-Ce and RAP-Ce were:4.14%,3.63%,3.06%respectively.4.We have examined the hydrolysis activity of three polysaccharides and their complexes on phosphate bond.The P-nitrophenyl phosphate disodium(PNPPNa2)was selected as a mimetic of phosphate bond.We have optimized the best hydrolysis conditions by orthogonal experiments.The conditions were:The substrate concentration is 3mmol/L,at 40 ?,pH 7.The results showed that the hydrolytic activity of complexes were higher than their corresponding polysaccharide.We compared the proteolytic activity of these three complexes and their polysaccharides:OCAP-Ce>AMP-Ce>RAP-Ce;OCAP>RAP>AMP.