基于超大孔聚合物微球的混合色谱模式层析介质的制备

以甲基丙烯酸缩水甘油酯与乙二醇二甲基丙烯酸酯共聚的超大孔聚合物微球为基质,采用聚乙烯亚胺和丁基缩水甘油醚先后衍生微球的表面,制备成兼具阴离子交换与疏水相互作用的混合色谱模式层析介质。考察离子交换基团、疏水配基密度对蛋白载量、回收率的影响,结果表明,在离子交换容量0.2~0.5 mol/mL范围内,随着介质离子交换容量的增大,蛋白载量及回收率均呈增加趋势,蛋白载量最高值达40 mg/mL,回收率大于90%。当疏水配基的密度大于0.03 mol/mL时,介质开始表现疏水相互作用。此超大孔混合模式色谱介质在大于2000 cm/h 的流速下依然能保持低于2 MPa 的柱背压,同时在高流速下(2880 cm/h)纯化人血清中的抗体应用中表现良好的分辨率。此介质在高通量分离纯化应用方面具有巨大潜力。     

致孔剂溶解度参数对大孔层析介质的结构影响研究

分别以甲基丙烯酸缩水甘油醚酯和乙二醇二甲基丙烯酸酯为功能单体和交联剂,采用悬浮聚合方法制备了大孔聚合物微球。考察了致孔剂的组成及用量对微球的孔径、比表面积的影响,其中随着致孔剂中的良溶剂(二氯甲烷δ=9.7(cal/cm~3)~(1/2)和不良溶剂(正辛醇δ=10.3(cal/cm~3)~(1/2)的比例变化,致孔剂体系溶解度参数可调范围为9.89~10.09(cal/cm~3)~(1/2),随着致孔剂与聚合物之间溶解度差值的增加,微球的孔径随之增大而比表面积呈下降趋势。将此类微球偶联聚乙烯亚胺衍生为阴离子交换层析介质,以前沿分析法比较了不同孔径的微球的传质性能,其中孔径为257 nm的介质仍能保持较高的动态蛋白载量(45.1 mg/m L),表明此类大孔介质在高通量分离纯化应用方面具有很大潜力。     

一种温敏型超大孔生物分离介质的制备及表征

采用改性琼脂糖对超大孔聚苯乙烯微球进行亲水化修饰(Agap-PS),通过酰基化反应在微球表面引入溴乙酰基(Agap-PS-Br),然后利用原子转移自由基聚合(ATRP)反应在Agap-PS-Br表面接枝温敏聚合物刷,得到一种温敏型超大孔生物分离介质(Agap-PS-PNIPAM).考察了配体、催化剂、溶剂和温度对N-异丙基丙烯酰胺ATRP反应的影响,在优化条件下PNIPAM的接枝量达到了15.07 mg/m2.采用红外光谱(FTIR)、扫描电镜(SEM)、压汞分析、激光共聚焦和蛋白吸附等手段对温敏型超大孔生物分离介质进行一系列表征,结果表明接枝温敏聚合物刷后Agap-PS-PNIPAM具有良好的温敏性,没有堵塞微球的超大孔,微球对蛋白的非特异性吸附大大降低.由于温敏聚合物刷发生了从亲水到疏水构象的转变,40℃时Agap-PS-PNIPAM对蛋白的吸附量是25℃时的2.69倍.压力流速实验表明Agap-PS-PNIPAM柱具有背压低、渗透性和机械稳定性好的优点,同样地由于PNIPAM链在40℃时收缩,此时Agap-PS-PNIPAM柱的床层渗透系数比25℃时提高了15.7％.     

肽配基纳米亲和载体定向固定化抗体

抗体经常被固定在某一固相载体表面用于免疫检测分析,但通常得到的是随机固定化的抗体,因而会影响抗体的活性。本文开发了一种新型的亲和载体用于抗体的定向固定化。即将与抗体IgG的Fc片段具有亲和作用的肽配基偶联于pGMA纳米球上,制备亲和载体用于吸附抗体实现抗体的定向固定化。首先利用乳液聚合法制备了粒径为110nm的pGMA纳米球,再以EDMA为交联剂并且在纳米球表面氨基化,最后将与抗体IgG的Fc片段具有亲和作用的肽配基HWRGWV偶联于纳米球表面,制备得到肽配基纳米球亲和载体。然后,考察了亲和载体对猪IgG的吸附行为。进一步,利用等温滴定微量量热仪研究了该纳米球亲和载体与IgG之间的相互作用热力学。结果表明,肽配基亲和载体对IgG的特异性吸附作用明显高于肽配基修饰前的载体。亲和载体与IgG的亲和作用主要贡献是疏水相互作用;而IgG与氨化纳米球载体的吸附作用则主要通过静电作用和氢键作用。所制得的纳米球亲和载体可用于进一步开发高效率、高灵敏度的临床免疫检测方法。     

大孔聚合物层析介质孔结构对蛋白载量的影响

分别以甲基丙烯酸缩水甘油酯和乙二醇二甲基丙烯酸酯作为功能单体和交联剂,采用悬浮聚合方法制备了大孔聚合物微球.考察了致孔剂组成对微球的孔径、比表面积的影响,并用聚乙烯亚胺将微球衍生为阴离子交换层析介质,考察了微球结构与蛋白载量之间的关系.结果表明,微球孔径尺寸随着致孔剂中不良溶剂用量[V(良溶剂)/V(不良溶剂)=1∶1～1∶3. 5]的增加而增大,而比表面积则呈相反趋势.离子交换容量(0. 11～0. 27 mmol/m L)与比表面积(4～38 m2/g)呈正相关,对应的蛋白静态结合载量亦呈正比关系.在所考察的孔径范围(301～1524 nm)内,蛋白动态结合载量先减少后保持稳定,即当孔径超过410 nm后,蛋白动态载量值保持在13 mg/m L不变,表明介质孔径超过此数值后蛋白载量不再受介质的比表面积影响.此外,以乙肝病毒表面抗原分子(HBs Ag,22 nm)为探针分子,利用激光共聚焦显微镜观察了该分子在微球内部的分布,结果表明,在该孔径考察范围内,HBs Ag均能完全扩散至微球内部.     

接枝多胺聚合物制备大孔阴离子交换色谱介质及其蛋白吸附行为评价

以环氧活化聚甲基丙烯酸酯大孔微球(FastSep-epoxy)为基质,通过接枝聚(烯丙基胺)(PAA)制备了大孔阴离子交换色谱介质(FastSep-PAA)。考察了介质的合成条件对离子交换容量(IC)及蛋白结合容量的影响,发现IC随PAA浓度、反应时间和溶液pH的增加均表现为增长趋势;同时结合蛋白吸附容量的变化选择了最优合成条件。通过扫描电子显微镜观察介质的表面形貌,发现其孔隙连通性较好,且接枝前后介质孔道结构无明显变化,PAA配基密度对介质结构无明显影响。此外,通过压汞法和氮气吸附法测定接枝前后不同介质的孔径尺寸和孔径分布情况,并考察该类介质的孔径与蛋白吸附行为的关系,发现其蛋白结合容量未出现随介质孔径尺寸增加而显著下降的现象,且孔径尺寸增加更有利于蛋白在介质内部传质。在126 cm/h的流速下FastSep-PAA介质的原始孔径(即FastSep-epoxy的孔径)为400 nm时的蛋白动态结合容量(DBC)最高(70.3 g/L),该孔径下介质比表面积大,蛋白可吸附位点较多;原始孔径为700 nm及以下的介质蛋白DBC均随流速增加而均有一定下降;原始孔径为1 000 nm的介质蛋...     

双孔色谱介质的制备和质粒DNA快速色谱纯化

以甲基丙烯酸缩水甘油酯为单体,二甲基丙烯酸乙二酯为交联剂,环己醇与十二醇为有机致孔剂,200 g/L的碳酸钙悬浮液为内水相(超孔致孔剂),用二次乳化法制备了(W/O)/W乳液,通过紫外光引发悬浮聚合生成两类孔型高分子微球(DEA-B).DEA-B孔径为双峰分布,范围分别为50~200 nm和500~5000 nm.其体积平均粒径、湿密度与不含超孔的微孔介质(DEA-M)接近.在流速为0.5 mL/min(150 cm/h)及相同的洗脱条件下,比较了所制备的微孔色谱介质填充的色谱柱与双孔色谱介质填充的色谱柱对5.4 kb质粒DNA的分离效果.结果表明,仅双孔介质色谱柱可以纯化质粒DNA,并且可以在1500 cm/h的高流速下得到色谱纯的质粒DNA,证明该双孔色谱介质可以用于质粒DNA的高速分离.     

碳纳米管复合微球修饰L-色氨酸及其对LDL的吸附性能

本文以多孔碳纳米管/活性炭复合微球为载体,以L-色氨酸为配基,采用环氧氯丙烷偶联法,制得修饰L-色氨酸的碳纳米管/活性炭复合微球(L-CNTs/AC)。采用扫描电镜、氮气吸附、傅立叶红外光谱、热分析、X射线光电子能谱等对复合微球进行表征;通过体外静态吸附法对其低密度脂蛋白(LDL)吸附能力进行初步研究。结果表明:环氧氯丙烷偶联法可接枝上L-色氨酸。复合微球中碳纳米管加入量越多,对LDL的吸附能力越强;当碳纳米管加入量为45wt%时,对LDL的吸附量达4.623 mg·g-1,是未添加碳纳米管的2.3倍多。这是因为碳纳米管不仅可促进复合微球中20~100 nm孔的形成,而且还可促进复合微球配基修饰量的增多,从而大大增强了复合微球对LDL的吸附能力。此复合微球可望开发成一种新型的血液灌流LDL吸附剂。     

混合模式色谱配基密度对抗体吸附分离性能的影响

作为蛋白A色谱的重要替代技术,混合模式色谱(mixed-mode chromatography,MMC)具有稳定、廉价和选择性好等优势。本文考察了以Sepharose Fast Flow为基质、4-(咪唑-1-基)苯胺(AN)为配基的新型色谱介质AN SepFF中配基密度对抗体吸附行为和分离性能的影响。研究结果表明,AN SepFF色谱介质在抗体吸附中具有21.2mmol/L的临界配基密度。在临界配基密度以上,抗体在色谱介质上具有较高的吸附容量和很低的解离常数并展现了相当程度的盐耐受性。动态吸附结果进一步表明,抗体的色谱介质中具有与商品化介质相当的动态吸附容量。抗体纯化的结果也表明,在临界配基浓度以上AN SepFF色谱表现出较好的纯化抗体的能力,其抗体产品纯度高于目前商品化的色谱介质;配基密度为55mmol/L时,AN SepFF色谱纯化抗体的收率达到91.9%。由此,AN SepFF色谱介质展现了巨大的应用前景。     

高分子微球偶联固定卡托普利药物分子的研究

采用无皂乳液聚合法制得聚苯乙烯-甲基丙烯酸缩水甘油酯(PSG)乳液微球,然后在微球表面嫁接空间臂分子1,6-己二胺,得到表面含氨基的PSGN微球,接着借助EDC/NHS催化作用将药物分子卡托普利化学偶联到PSGN微球表面,制成固定卡托普利的亲和PSG微球。实验着重考察了PSGN微球偶联固定卡托普利反应过程中催化剂比例和用量、pH值、反应温度和时间等的影响规律。结果表明,在25℃,pH为4.0,m(NHS)∶m(EDC)=1∶2,EDC的浓度为4mg/mL的条件下,卡托普利偶联到微球表面的效果较好。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.