【作者】 王羽；

【导师】 万谦宏；

【作者基本信息】 天津大学 ， 应用化学， 2012， 博士

【摘要】 随着生物医药分析领域的不断发展,生物样品的预处理过程对建立一个可靠准确的药物分析方法至关重要。传统方法包括液液萃取和固相萃取法。近年来,磁性固相萃取以快速简便且易于实现自动化高通量操作的优势而得到快速发展。然而,生物样品中存在的大量内源性蛋白在磁性粒子表面发生的不可逆非特异性吸附作用,不仅会使磁性吸附剂对分析物的吸附能力降低,同时也容易使磁性粒子发生团聚而无法反复使用。为了消除生物样品基质中大分子蛋白质的干扰,近年来发展起来的限进性固相萃取在线联用技术具有一定优势,其主要特点在于吸附材料的外表面具有亲水性屏障,结合孔径排阻效应,消除了蛋白在表面吸附和孔道堵塞等问题,而孔内修饰的疏水或离子交换基团可直接从生物样品中富集目标物质,因此是一种被广泛应用于复杂生物样品及环境分析的生物样品预处理技术。然而其在线固相萃取的应用模式从富集到分析通常只能完成单个样品的操作,从而会导致机时利用率低,不能满足生物样品处理的高通量化要求。本论文着眼于满足当前高通量化的生物样品预处理需求和解决传统磁性固相吸附剂表面蛋白吸附的问题,将限进性概念结合到磁性分离技术中来,提出了基于限进性磁性固相萃取材料的制备策略。为此,本论文开发了基于不同磁性基质、内表面多样化的一系列磁性限进材料。具体研究成果如下所述:1.采用多孔γ-Fe₂O₃ @ SiO2磁性硅胶作为基质,经过二醇基表面键合、十八烷基转化以及脂肪酶选择性水解等步骤,制备了内表面疏水而外表面亲水的新型限进磁性材料。以牛血清白蛋白和甲氨蝶呤及其结构类似物亚叶酸钙、叶酸作为模型化合物证明了其外表面的亲水基团及适宜的孔径对大分子蛋白的排阻能力以及内表面的疏水基团对小分子物质的萃取能力。以其作为磁性限进固相吸附剂,对人血清基质中三种小分子治疗药物的萃取条件进行了优化,并结合反相-高效液相色谱建立了分析方法,其良好的特异性、线性以及重复性均体现出了新型磁性限进萃取材料的优越性和稳定性,为临床治疗药物监测及生物样品高通量自动化快速检测提供了潜在的应用前景。2.由于1中的材料与三种治疗药物的结合能力较弱,因此本章将1中的多孔磁性硅胶先进行环氧基修饰,然后采用粒径约为50μm聚合物酸将外表面的环氧基先开环形成二醇基,然后再以十八胺、亚硫酸氢钠及三乙胺盐酸盐分别与内表面残余的环氧基进行反应,最终可以得到内表面依次为十八烷基、磺酸基和季铵盐基而外表面为二醇基的新型磁性限进材料,避免了上一章节采取的脂肪酶水解法只能制备内表面为烷基基团的单一化类型。我们仍选择1中的四种物质作为模型,并通过Langmuir吸附等温曲线,比较了三种磁性限进吸附剂对它们的饱和吸附容量,其结果表明,外表面的二醇基可以起到排阻蛋白的作用,而且内表面为磺酸基和季铵盐基的磁性限进材料对小分子物质的吸附量要远远高于内表面为十八烷基的材料,说明甲氨蝶呤及两种结构类似物更适合采用阴离子或阳离子交换模式来萃取,同时也证明了聚合物酸开环法比脂肪酶水解法在内表面多样化修饰方面的可行性和优势。3.由于1和2中材料的孔径还不能满足对生物样品中具有功能性但分子量较大的多肽及蛋白质富集的要求,因此我们在上述6 nm孔径的磁性硅胶基础上,利用浸盐法对其进行扩孔处理,并通过形貌、晶型、磁性、比表面积变化来表征和筛选,最终确定300℃和400℃两个温度为最佳的扩孔条件。同样采用聚合物酸开环法制备了内表面为十八烷基外表面为二醇基的扩孔磁性限进材料,并通过对胸腺五肽、胰岛素以及牛血清白蛋白三种不同分子量模型物质的吸附证明了扩孔后的材料明显对后两者的吸附量增大,表明此法可以在不破坏磁性基质性质的基础上对不同分子量大小的生物分子具有不同程度的限进效果,使其在提取和富集复杂生物样品中分子量不同的功能性目标物时具有更高的选择性。4.为了进一步开发新方法来制备磁性限进材料,本章首先以模板法制备的多孔γ-Fe₂O₃作为磁核,再以十六烷基三甲基溴化铵为结构导向剂,利用sol-gel原理,采用层层包覆的方法将环氧基硅烷试剂作为外层亲水性二醇基的功能前体,以氨基、巯基、苯基以及羧基硅烷试剂作为修饰内层的功能单体,制备得到外表面为二醇基而内表面分别为氨基、磺酸基、苯磺酸基和羧基的核壳型磁性限进介质。我们以内表面为氨基的磁性限进介质作为模型材料,通过红外光谱、高倍透射电镜、荧光淬灭实验、磁滞回线等手段证明了在制备过程中模板的有效去除、表面壳层和其孔道结构的形成、孔道所具备的限进性以及磁性能的变化。对于其它三种基于离子交换分配原理的核壳型磁性限进材料,我们进一步以牛血清白蛋白及硫酸特布他林、硫酸沙丁胺醇和盐酸克伦特罗三种瘦肉精物质作为模型化合物,进行模型吸附实验来评价三种材料的限进性。其结果表明该方法可以将任意一种、或两种以上,甚至是整体功能化硅烷试剂直接修饰到内表面上,比脂肪酶水解及聚合物酸开环等制备方法的灵活性和选择性更强,这也为制备磁性限进材料提供了一条新的思路和途径。更多还原

【Abstract】 With growing demand for fast analysis in the fields of pharmaceutical industry and biomedical research, the pretreatment of biological samples is of great importance in establishing a reliable and accurate analytical method. Magnetic solid phase extraction （MSPE） with the advantages of fast and simple procedures and being amenable to high-throughput operation has gradually taken the place of traditional technologies including liquid-liquid extraction （LLE） and solid-phase extraction （SPE）. However, the fouling of proteins on the surface of magnetic particles gives rise to particles aggregation, leading to declined binding capacity for analytes and reusability of the particles.Recently, restricted access SPE has been developed to be as a type of on-line extraction technology enabling the direct enrichment of analytes while eliminating macromolecules from biological fluids. One of major advantages over traditional SPE is that the external surface of restricted access meterials （RAMs） has hydrophilic groups combined with limited pore size as barriers which prevent surface adsorption and pore channel blocking. The interior surface modified with hydrophobic and ion-exchange groups can directly extract low weight targets from biological samples. Therefore, the RAM has been widely applied for pretreatment technology in the fields of biological and environmental analysis. However, the only single biological sample can be treated from enrichment to analysis under this kind of on-line extraction mode, which will cause the low availability of the instrument and cannot satisfy the requirement of high-throughput in biological fluids.In order to meet the need of high-throughput of biological samples and to provide solutions for the particle fouling due to protein adsorption on the surface, efforts have been made in this thesis to develop preparation methods by which the restricted access properties are incorporated into the magnetic separation materials so as to provide novel restricted access materials for magnetic solid-phase extraction.The major results presented in this thesis are outlined as follows:1. The magnetic silica particles served as scaffolds were first modified with diol groups, which were then converted to octadecyl esters through reaction with stearoyl chloride. In the second step, the octadecyl esters on the exterior surface were hydrolyzed by the action of lipase to yield magnetic RAM particles with hydrophobic reverse-phase ligands on the inner surface and biocompatible diol groups on the outer surface. The restricted access behavior of the resulting materials was confirmed by differential binding of small molecules such as methotrexate （MTX）, calcium folinate （CF）, and folic acid （FA） relative to bovine serum albumin （BSA）. While the three model drugs were bound to the magnetic particles with high affinity, the adsorption of the proteins was markedly reduced due to size exclusion effect. The utility of the magnetic particles for sample preparation was tested in solid-phase extraction of MTX, CF and FA from spiked human serum and the effects of the SPE conditions on the recovery of the analytes were systematically studied. Moreover, the magnetic particle-based sample preparation procedures coupled with reversed-phase liquid chromatography analysis were developed and validated. This dual functionality material may be adapted in automated and high-throughput protocols for routine analysis of a large volume of clinical samples.2. Owing to the weak binding strength between three model drugs and the materials from above method, porous magnetic silica was first modified with epoxy groups, which were reacted with polymeric acid with particle size 50μm to yield only diol groups at the outer surface. In the second step, three compounds, octadecylamine, sodiumhydrogensulfite and triethylamine hydrochloride, respectively, were reacted with epoxy groups at the inner surface to give rise to magnetic RAM particles with octadecyl, sulfonic and quaternary ammonium on the inner surface and diol groups on the outer surface. This synthesis method can avoid the single type with only modified into alkyl groups on the inner surface aboved as lipase hydrolysis. The model molecules above mentioned were still used to compare the binding capacity of three magnetic RAMs through Langmuir adsorption isotherm curves. The results showed that the adsorption amount of materials with sulfonic and quaternary ammonium on the inner surface was significantly higher than that with octadecyl groups, implying that MTX and its structural analogs can be extracted more efficiently by ion exchange model. Furthermore, the open-ring methods based on polymeric acid has more advantageous in the interior versatilities over that based on lipase hydrolysis.3. In order to enhance adsorptive capacity on biological polypeptides with high molecule weight, the salt impregnation was carried out and followed by calcination at different temperatures to produce wide poreγ-Fe₂O₃@SiO2 magnetic silica. The optimal wide pore conditions were defined at the temperature of 300℃and 400℃ through the characterization of morphology, crystallization, magnetism and surface area of magnetic silica particles. The wide-pore material was then further modified into RAM particles with octadecyl groups on the inner surface and diol groups on the outer surface by the open-ring reaction of polymeric acid. Three kinds of different molecule weight of biological polypeptides, including Thymopentin （TP-5）、Insulin and BSA, were chosen as model compounds to perform the adsorption, which indicated that the wide pore materials were higher binding capacity on Insulin and BSA, and the ability of exclusion with different degree. This also offers the potential high selectivity for extraction and enrichment of different molecule weight of functional targets from complex biological fluids.4. In order to develop novel methods to prepare magnetic RAM, porousγ-Fe₂O₃ microspheres were chosen as magnetic core, cetyltrimethylammonium bromide （CTAB） as structure direction agent, and layer by layer coating method based on sol-gel principles was adopted to modify through different types of silanes with functional groups, which yielded core-shell magnetic RAM particles with amino, sulfonic, phenylsulfonic or caroxyl groups at the inner surface and diol groups at the outer surface. First, the magnetic RAMs with amino groups at the inner surface was used as model material, all kinds of characterization tools including FT-IR, HRTEM, and fluorescence quenching and magnetism curves had been used to confirm that the template was removed effectively to form surface shell and porous channel together with restricted access properties. The adsorption experiments of macromolecules BSA and basic model small weight compounds such as Terbutaline （TER）, Salbutamol （SAL） and Clenbuterol （CLB） were chosen to exhibit the dual surface functional properties from the latter three core shell magnetic RAMs based on ion-exchange principles. The results indicated that the one kind, or over two kinds and even the whole silanes agent could be directly grafted onto the inner surface of particles, which have more selective and versatile than above methods. This also provides a novel thought for preparation of magnetic RAMs.更多还原