| Phenylboronic acid（PBA）is a unique molecule that can specifically recognize cis-dihydroxy compounds such as nucleosides,catechols,sugars,glycoproteins,etc.through a reversible covalent reaction.The boron affinity reaction depends on the environmental p H.Under high p H conditions,PBA can form a covalent complex with the cis-dihydroxy compound.When the environmental p H decreases,the complex dissociates into the original PBA and the cis-dihydroxy compound.The p H-controllable capture/release characteristics of PBA provide great feasibility for the development of p H-responsive materials,and show good application prospects in separation,sensing,imaging,diagnosis,and drug delivery.However,the current boron affinity materials still have problems such as weak affinity,low adsorption capacity and serious non-specific adsorption.Therefore,the design and development of boron affinity functional materials with better performance has important application value and research significance.Aiming at the above-mentioned problems of boron-affinity materials,this thesis adopts two strategies of"one-pot method"and"post-modification method".By optimizing the synthesis conditions,a series of boron-affinity organic polymer polymers have been designed and synthesized.Types of boron affinity silica gel polymers,and various characterization and evaluation tests have been carried out on these polymer materials.The specific research results are as follows:1.Using 3-vinylbenzeneboronic acid as the boric acid monomer,and three different crosslinking agents(N,N’-methylene bisacrylamide（MBAA）,ethylene glycol dimethyl dimethacrylate（EGDMA）and trimethylpropane trimethacrylate（TRIM）,using the"one-pot method"in different solvent systems to prepare a series of different types of phenylboronic acid organic polymer particles.After optimizing the reaction conditions,it was found that B3 synthesized with MBAA as a cross-linking agent in DMSO solvent exhibited ultra-high specificity for cis-dihydroxy compound molecules,and almost no non-specific adsorption.The boron affinity polymer has a one-time adsorption recovery rate of 88%（adenosine）,69%（guanosine）,63%（cytidine）,and 73%（guanosine）for common nucleoside molecules in 30 minutes.Reach the adsorption equilibrium.Through adsorption equilibrium experiments,the dissociation constants of this type of boron affinity polymer for adenosine and catechol are 9.8×10-5 M and 2.0×10-4 M,respectively,and the maximum adsorption capacity is 46μmol/g and 166μmol/g.The experimental test results show that the material can be used for the selective enrichment and separation of nucleoside molecules in urine.2.Through the reaction of 3-formylphenylboronic acid（3-FPBA）and 3-aminopropyltriethoxysilane（APTES）to obtain the new boric acid monomer 3-FPBA-APTES,and use ethyl orthosilicate as the cross-linker Linking agent,a series of boric acid functionalized silica gel particles were prepared using the"one-pot method"in different solvent systems,focusing on the ratio of boric acid monomer and crosslinking agent,and obtaining boric acid functionalized silica gel under optimal conditions Particle P43B,the boric acid functionalized silica gel particles can adsorb cis-dihydroxy compounds such as nucleosides and catechols with high selectivity.The adsorption recovery rate of nucleosides is 32%（adenosine）and 47%（uridine）,6%（cytidine）,19%（guanosine）,lower than the adsorption recovery rate of boron affinity organic polymer B3,but can complete the adsorption within 2 minutes,faster than the adsorption equilibrium time of B3.Through adsorption equilibrium experiments,the dissociation constants of P43B for adenosine and catechol are determined to be7.6×10-5M and 6.7×10-4M,respectively,which are equivalent to the boron affinity of B3;the maximum adsorption capacity is 25.8μmol/g and 68.6μmol/g,which is lower than the theoretical maximum adsorption capacity of B3.Although the performance of the boron affinity silica gel particles prepared by this method is lower than that of the boron affinity organic polymer particles,the reaction does not require heating,the material is environmentally friendly,the preparation cost is relatively low,and the material can also be successfully used in urine Selective extraction and separation of nucleoside molecules.3.In order to increase the adsorption capacity of boron-affinity silica particles,we introduced a new intermediate reagent,namely triphenyl aldehyde（BTA）,so that two molecules of 3-aminophenylboronic acid（APBA）can be reacted with Schiff base One molecule of APTES is reacted to obtain a new boronic acid silane reagent（3-APBA）2-BTA-APTES containing two phenylboronic acid functional groups.Using the new boric acid silane reagent as the boric acid monomer and ethyl orthosilicate as the crosslinking agent,a series of boric acid functionalized silica particles were prepared in different solvent systems using the"one-pot method",and different boric acid monomers were investigated.The ratio of body to crosslinking agent.After optimizing the reaction conditions,the obtained boric acid functionalized silica particles N1 has a one-time adsorption recovery rate of 83%,89%,84%and 92%for adenosine,uridine,cytidine and guanosine,which is not only better than boron.The affinity silica gel particle B3 is better than the boron affinity organic polymer particle P43B;the boron affinity silica gel particle can reach the adsorption equilibrium of the cis-dihydroxy compound within 10 minutes.Through adsorption equilibrium experiments,the dissociation constants of this type of boron affinity material for adenosine and catechol are 8.4×10-4 M and 2.7×10-4 M,respectively,which are not different from the boron affinity of B3 and P43B.The maximum adsorption capacity is 194.3μmol/g and 734.9μmol/g,which are much higher than the theoretical adsorption capacity of B3 and P43B.Based on the excellent boron affinity of N1,it shows better enrichment and separation ability in the test of selective enrichment of nucleoside molecules in urine.4.In addition,we also prepared phenylboronic acid-functionalized silica nanoparticles Si O2-NH2-BTA-APBA through the"post-modification method"using mesitylene aldehyde as the bridge and amino-functionalized silica nanoparticles as the basic material.Although the material can adsorb cis-dihydroxy compounds with high selectivity,its one-time adsorption recovery rate for nucleosides is only 1%（adenosine）,1%（guanosine）,6%（cytidine）,9%（Guanosine）;the dissociation constants of p-adenosine and catechol are 5.8×10-3M and 2.1×10-3M,respectively,and the maximum adsorption capacities of adenosine and catechol are 0.58μmol/g and 14.7μmol/g.All properties are significantly worse than the boron affinity silica gel particles N1 prepared by the"one-pot method". |
