Gene Transfection in High Serum Levels: Case Studies with New Cholesterol Based Cationic Gemini Lipids

Background: Six new cationic gemini lipids based on cholesterol possessing different positional combinations of hydroxyethyl (-CH2CH2OH) and oligo-oxyethylene -(CH2CH2O)(n)- moieties were synthesized. For comparison the corresponding monomeric lipid was also prepared. Each new cationic lipid was found to form stable, clear suspensions in aqueous media. Methodology/Principal Findings: To understand the nature of the individual lipid aggregates, we have studied the aggregation properties using transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements and X-ray diffraction (XRD). We studied the lipid/DNA complex (lipoplex) formation and the release of the DNA from such lipoplexes using ethidium bromide. These gemini lipids in presence of a helper lipid, 1, 2-dioleoyl phophatidyl ethanol amine (DOPE) showed significant enhancements in the gene transfection compared to several commercially available transfection agents. Cholesterol based gemini having -CH2-CH2-OH groups at the head and one oxyethylene spacer was found to be the most effective lipid, which showed transfection activity even in presence of high serum levels (50%) greater than Effectene, one of the potent commercially available transfecting agents. Most of these geminis protected plasmid DNA remarkably against DNase I in serum, although the degree of stability was found to vary with their structural features. Conclusions/Significance: -OH groups present on the cationic headgroups in combination with oxyethylene linkers on cholesterol based geminis, gave an optimized combination of new genera of gemini lipids possessing high transfection efficiency even in presence of very high percentage of serum. This property makes them preferential transfection reagents for possible in vivo studies.

AIPE-active green phosphorescent iridium(III) complex impregnated test strips for the vapor-phase detection of 2,4,6-trinitrotoluene (TNT)

Detection of explosives, especially trinitrotoluene (TNT), is of utmost importance due to its highly explosive nature and environmental hazard. Therefore, detection of TNT has been a matter of great concern to the scientific community worldwide. Herein, a new aggregation-induced phosphorescent emission (AIPE)-active iridium(III) bis(2-(2,4-difluorophenyl)pyridinato-NC2') (2-(2-pyridyl)benzimidazolato-N,N') complex FIrPyBiz] has been developed and serves as a molecular probe for the detection of TNT in the vapor phase, solid phase, and aqueous media. In addition, phosphorescent test strips have been constructed by impregnating Whatman filter paper with aggregates of FIrPyBiz for trace detection of TNT in contact mode, with detection limits in nanograms, by taking advantage of the excited state interaction of AIPE-active phosphorescent iridium(III) complex with that of TNT and the associated photophysical properties.

Velocity Fluctuations in Helical Propulsion: How Small Can a Propeller Be

Helical propulsion is at the heart of locomotion strategies utilized by various natural and artificial swimmers. We used experimental observations and a numerical model to study the various fluctuation mechanisms that determine the performance of an externally driven helical propeller as the size of the helix is reduced. From causality analysis, an overwhelming effect of orientational noise at low length scales is observed, which strongly affects the average velocity and direction of motion of a propeller. For length scales smaller than a few micrometers in aqueous media, the operational frequency for the propulsion system would have to increase as the inverse cube of the size, which can be the limiting factor for a helical propeller to achieve locomotion in the desired direction.

Tripodal Bile Acid Architectures Based on a Triarylphosphine Oxide Core Obtained by Copper-Catalysed 1,3]-Dipolar Cycloaddition: Synthesis and Preliminary Aggregation Studies

We report the synthesis and aggregation behaviour of new water-soluble, bile acid derived tripodal architectures based on a core derived from triphenylphosphine oxide. We employed the well-established copper-catalysed 1,3]-dipolar cycloaddition (CuAAC) for the construction of these tripodal molecules. The aggregation behaviour of these molecules in aqueous media was studied by different analytical methods such as dye solubilisation, dynamic light scattering, NMR and AFM. These molecular architectures also offer an additional advantage in aiding understanding of the influence of the nature of the bile acid backbone and of the configuration at the steroid C-3 position in these architectures; to the best of our knowledge this has not been reported in the literature. The unique gelation properties of the -derivatives were explained through molecular modelling studies and the mechanical behaviour of these gels was studied by rheology experiments.

The morphology dependent electrocatalytic activity of Ir nanostructures towards oxygen reduction

Iridium nanostructures with different morphologies are synthesized by a simple, environmentally friendly approach in aqueous media under mild conditions. The morphology dependent electrocatalytic activity of Ir nanochains and nanoparticles towards oxygen reduction reaction (ORR) has been demonstrated in both acidic and alkaline media. Comparative electrochemical studies reveal that nanochains exhibit significantly enhanced ORR activities in both acidic and alkaline media as compared with nanoparticles, as a result of the continuous structure of interconnected particles. The mechanism of oxygen reduction on Ir nanostructures predominantly follows a four-electron pathway in alkaline and acidic solutions. Excellent stability and good selectivity towards methanol tolerance are reported.

Substitution-Modulated Anticancer Activity of Half-Sandwich Ruthenium(II) Complexes with Heterocyclic Ancillary Ligands

Ten new organometallic half-sandwich ruthenium complexes with heterocyclic ligands have been synthesized (H1-H10). The substituents on the ancillary heterocyclic ligands were varied to understand the effect of substitution on anticancer activity. The crystallographic characterization of five complexes confirms that they adopt three-legged piano-stool structures and are stabilized by intramolecular hydrogen bonding. Complexes H2 and H3 also exhibit halogen bonding in the solid state. In aqueous media, the complexes form dinuclear ruthenium species. Complex H1 with a noncytotoxic heterocycle, 6-fluoro-2-mercaptobenzothiazole, and complex H11 with the unsubstituted 2-mercaptobenzothiazole are the most active against A2780 and KB cell lines. The substitution of the H atoms on the ancillary ligand with Cl or Br atoms leads to a decrease in the anticancer activity. With the exception of fluorine-substituted H5, the complexes with mercaptobenzoxazole (H6-H9) are inactive against all of the tested cell lines. Ruthenium complexes with mercaptonaphthimidazole (H10) and mercaptobenzimidazole (H13) do not show any anticancer activity. The active complexes show a biphasic melting curve when incubated with calf thymus (CT) DNA. These complexes only inhibit thioredoxin reductase (TrxR) enzyme activity to a small extent. The substitution of hydrogen atoms with fluorine atoms in the aromatic heterocyclic ligands on organometallic half-sandwich ruthenium complexes has the most beneficial effect on their anticancer activity.

How does spacer length of imidazolium gemini surfactants control the fabrication of 2D-Langmuir films of silver-nanoparticles at the air-water interface?

A series of gemini surfactants based on cationic imidazolium ring as polar headgroup, abbreviated as lm-n-lm], 2Br(-) (n = 2, 5, 6 and 12), was synthesized. Their ability to stabilize silver nanoparticles in aqueous media was investigated. The resulting suspensions were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). They exhibit specific morphologies by adopting different supramolecular assemblies in aqueous media depending on the internal packing arrangements and on the number of spacer methylene units -(CH2)(n)-]. Individual colloids were extracted from the aqueous to chloroform layer and spread at the air/water interface to allow the formation of well-defined Langmuir films. By analysis of the surface pressure-area isotherms, the details about the packing behavior and orientation of the imidazolium gemini surfactant capped silver nanoparticles were obtained. Morphological features of the dynamic process of monolayer compression at the air-water interface were elucidated using Brewster angle microscopy (BAM). These monolayers were further transferred on mica sheets by the Langmuir-Blodgett technique at their associated collapse pressure and the morphology of these monolayers was investigated by atomic force microscopy (AFM). The number of spacer methylene units -(CH2)(n)-] of the gemini surfactants exerted critical influence in modulating the characteristics of the resulting Langmuir films. (C) 2014 Elsevier Inc. All rights reserved.

How does spacer length of imidazolium gemini surfactants control the fabrication of 2D-Langmuir films of silver-nanoparticles at the air-water interface?

A series of gemini surfactants based on cationic imidazolium ring as polar headgroup, abbreviated as Im-n-Im], 2Br(-) (n = 2, 5,6 and 12), was synthesized. Their ability to stabilize silver nanoparticles in aqueous media was investigated. The resulting suspensions were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). They exhibit specific morphologies by adopting different supramolecular assemblies in aqueous media depending on the internal packing arrangements and on the number of spacer methylene units -(CH2)(n)-]. Individual colloids were extracted from the aqueous to chloroform layer and spread at the air/water interface to allow the formation of well-defined Langmuir films. By analysis of the surface pressure-area isotherms, the details about the packing behavior and orientation of the imidazolium gemini surfactant capped silver nanoparticles were obtained. Morphological features of the dynamic process of monolayer compression at the air-water interface were elucidated using Brewster angle microscopy (BAM). These monolayers were further transferred on mica sheets by the Langmuir-Blodgett technique at their associated collapse pressure and the morphology of these monolayers was investigated by atomic force microscopy (AFM). The number of spacer methylene units (CH2)(n)-] of the gemini surfactants exerted critical influence in modulating the characteristics of the resulting Langmuir films. (C) 2014 Elsevier Inc. All rights reserved.

Electrochemical exfoliation of graphite for producing graphene using saccharin

A green electrochemical exfoliation route to produce graphene from graphite electrode has been provided. Saccharin which is a non-toxic and biocompatible artificial sweetener was used as an intercalating agent in aqueous media. Graphene samples were produced using five different exfoliation potentials. Microscopic and spectroscopic analysis confirmed the presence of few layer graphene sheets in as-exfoliated product. Important observations made were: (a) graphene layers from nano-to-micro meter sizes were produced; (b) number of graphene layers decreased with increase in the intercalation potential, (c) yield of graphene increased with increase in the exfoliation potential and (d) defect density in the exfoliated graphene layer was sensitive to the exfoliation potential in a way that with increase in the exfoliation potential the defect density initially increased and then eventually decreased.

The electrocatalytic and stoichiometric oxidation chemistry of binuclear ruthenium complexes incorporating the anionic tripod ligand {(η5-C5H5)Co[P(OCH3)2(=O)]3}-

The anionic tripod ligand NaLoMe (L_(oMe) - = [(η^5-C_5H_5)Co{P(O)(OCH_3)_2}_3]^-) reacts with RuO_4 in a biphasic reaction mixture of 1% H_2SO_4 and CCI_4 to afford [(L_(oMe) (HO)Ru^(IV) (µ-O)_2Ru ^(IV)(OH)(L_(oMe)] (1), which is treated with aqueous CF_3S0_3H to generate [(L_(oMe)(H_2O)Ru^(IV) (µ-O)_2R^(IV) (OH_2)(L_(oMe)][CF_3SO_3]_2 ([H_21][CF_3SO_3]_2). Addition of iodosobenzene to an acetonitrile solution of this salt yields [(L_(oMe)(O)Ru^v(µ-0)2Ru^v-(O)(_(LoMe)] (2). The dimer 1 can be reduced chemically or electrochemically to the Ru^(III)- Ru^(III) dimers [(L_(oMe)(H_20)Ru^(III) (µ-OH)_2Ru^(III) (OH_2)(L_(oMe)) ]^2+ and [(L_(oMe)) ^(III) (µ-0Hh(µ-0H2)Ru^(III) (L_(oMe)]^2+ which interconvert in aqueous media. Two electron processes dominate both the bulk chemistry and the electrochemistry of 1. Among these processes are the quasi-reversible Ru^(IV) - Ru^(IV)/Ru^(III)- Ru^(III) and Ru^(III)- Ru^(III)/ Ru^(II)- Ru^(II) reductions and a largely irreversible Ru^(V) - Ru^(V)/ Ru^(IV) - Ru^(IV)/oxidation. The dioxo dimer 2 oxidizes alcohols and aldehydes in organic media to afford 1 and the corresponding aldehydes and acids. Analogously, the Ru^(V) - Ru^(V)/ Ru^(IV)- Ru^(IV) redox wave mediates the electrooxidation of alcohols and aldehydes in aqueous buffer. In this system, substrates can be oxidized completely to CO_2. The kinetic behavior of these oxidations was examined by UV-vis and chronoamperometry, respectively, and the chemistry is typical of metal-oxo complexes, indicating that electronic coupling between two metal centers does not dramatically affect the metal-oxo chemistry. Dimer [H_21]^(2+) also reacts with alcohols, aldehydes, and triphenylphosphine in CH_3CN to afford Ru^(III)- Ru^(III) products including [(L_(oMe))CH_3CN) Ru^(III) (µ-OH)_2 Ru^(III) (NCCH_3)( L_(oMe))][CF_3SO_3]2 (characterized by X-ray crystallography) and the corresponding organic products. Reaction of 1 with formaldehyde in aqueous buffer quantitatively affords the triply bridged dimer [(L_(oMe)Ru^(III) (µ-OH)2- (µ-HCOO) Ru^(III) (L_(oMe)][CF_3SO_3] (characterized by X-ray crystallography). This reaction evidently proceeds by two parallel inner-sphere pathways, one of which is autocatalytic. Neither pathway exhibits a primary isotope effect suggesting the rate determining process could be the formation of an intermediate, perhaps a Ru^(IV) - Ru^(IV) formate adduct. The Ru^(III)- Ru^(III)formate adduct is easily oxidized to the Ru^(IV) - Ru^(IV) analog [(L_(oMe)Ru^(IV)(µ-OH)_2-(µ-HCOO) Ru^(IV) (L_(oMe)][CF_3SO_3], which, after isolation, reacts slowly with aqueous formaldehyde to generate free formate and the Ru^(III)- Ru^(III) formate adduct. These dimers function as catalysts for the electrooxidation of formaldehyde at low anodic potentials (+0.0 V versus SCE in aqueous buffer, pH 8.5) and enhance the activity of Nafion treated palladium/carbon heterogeneous fuel cell catalysts.

Reaction of glucose catalyzed by framework and extraframework tin sites in zeolite beta

The isomerization of glucose into fructose is a large-scale reaction for the production of high-fructose corn syrup, and is now being considered as an intermediate step in the possible route of biomass conversion into fuels and chemicals. Recently, it has been shown that a hydrophobic, large pore, silica molecular sieve having the zeolite beta structure and containing framework Sn⁴⁺ (Sn-Beta) is able to isomerize glucose into fructose in aqueous media. Here, I have investigated how this catalyst converts glucose to fructose and show that it is analogous to that achieved with metalloenzymes. Specifically, glucose partitions into the molecular sieve in the pyranose form, ring opens to the acyclic form in the presence of the Lewis acid center (framework Sn⁴⁺), isomerizes into the acyclic form of fructose and finally ring closes to yield the furanose product. Akin to the metalloenzyme, the isomerization step proceeds by intramolecular hydride transfer from C2 to C1. Extraframework tin oxides located within hydrophobic channels of the molecular sieve that exclude liquid water can also isomerize glucose to fructose in aqueous media, but do so through a base-catalyzed proton abstraction mechanism. Extraframework tin oxide particles located at the external surface of the molecular sieve crystals or on amorphous silica supports are not active in aqueous media but are able to perform the isomerization in methanol by a base-catalyzed proton abstraction mechanism. Post-synthetic exchange of Na⁺ with Sn-Beta alters the glucose reaction pathway from the 1,2 intramolecular hydrogen shift (isomerization) to produce fructose towards the 1,2 intramolecular carbon shift (epimerization) that forms mannose. Na⁺ remains exchanged onto silanol groups during reaction in methanol solvent, leading to a near complete shift in selectivity towards glucose epimerization to mannose. In contrast, decationation occurs during reaction in aqueous solutions and gradually increases the reaction selectivity to isomerization at the expense of epimerization. Decationation and concomitant changes in selectivity can be eliminated by addition of NaCl to the aqueous reaction solution. Thus, framework tin sites with a proximal silanol group are the active sites for the 1, 2 intramolecular hydride shift in the isomerization of glucose to fructose, while these sites with Na-exchanged silanol group are the active sites for the 1, 2 intramolecular carbon shift in epimerization of glucose to mannose.

Síntese e caracterização de TiO2 puro e modificado para aplicações ambientais

Fotocatalisadores baseados em nanopartículas de dióxido de titânio modificados fornecem soluções em potencial para a mineralização de poluentes orgânicos em meio aquoso. Agentes modificadores têm sido amplamente investigados com o objetivo de promover a fotoativação pela luz visível. Foram estudadas a nível fundamental até aqui, as modificações estruturais, texturais e óticas causadas pela introdução de silício e nitrogênio na rede da titânia. Titânias puras (TiO2) e modificadas nanoestruturadas, particularmente titânias modificadas com silício (TiO2-SiO2), com razões atômicas Si/Ti de 0,1, 0,2 e 0,3 foram sintetizadas pelo método sol-gel a partir da hidrólise ácida de isopropóxido de titânio(IV) e tetraetoxisilano. As metodolo-gias sintéticas desenvolvidas tentaram aderir aos princípios da Química Verde, dispensando o uso de atmosfera inerte e temperatura e pressão elevadas, o que foi alcançado utilizando-se, principalmente, a agitação ultrassônica. Titânias modificadas com silício e dopadas com ni-trogênio (TiO2-SiO2-N) foram obtidas a partir do pré-tratamento de TiO2-SiO2 a 500 C ao ar e então submetidas ao fluxo de amônia (NH3) a 600 C por 1-3 h e, após resfriamento, foram recozidas a 400 C ao ar. Amostras distintas foram caracterizadas, na forma de pó seco e após calcinação entre 400600 C, por difração de raios X, adsorção de nitrogênio, microscopia eletrônica de varredura e espectroscopia de refletância difusa no UV-Visível. As titânias pu-ras, obtidas principalmente variando-se a razão de hidrólise, foram cristalizadas na forma de anatásio como fase predominante até 600 C, além de traços de brookita presente até 500 C. O rutilo foi identificado a partir de 600 C como fase minoritária, embora apresentando tama-nhos de cristal significativamente maiores que os estimados para o cristal de anatásio. As titâ-nias modificadas com até 20% de silício apresentaram notável estabilidade térmica, evidenci-ada pela presença exclusiva de anatásio até 900 C. Foi também observado o aparecimento de macroporos com diâmetro médio em torno de 55 nm após calcinação a 400 C, diferentemente do que se observou nas amostras em geral. A introdução de baixo teor de silício assegurou às titânias calcinadas valores elevados de área específica, atribuído ao efeito de contenção acentuada na taxa de crescimento do cristal. As titânias modificadas com silício e as titânias puras obtidas com taxa de hidrólise 25:1 para a razão H2O : Ti apresentaram mesoporos com diâmetros médios de mesma dimensão do cristal. As titânias modificadas com silício e dopa-das com nitrogênio apresentaram absorção na região visível entre 400-480 nm, com discreta redução da energia de band gap para as transições eletrônicas consideradas. Titânias calcina-das a 300−400 C apresentaram desempenho fotocatalítico semelhante ao TiO2 P25 da De-gussa sob irradiação UV, na degradação do azo corante Reactive Yellow 145 em soluções a-quosas em pH 5 a 20 1C

Avaliação de complexos de inclusão na inibição do aço carbono em meio ácido

A indústria de petróleo e gás apresenta sérios problemas relacionados à corrosão. Nas petroquímicas e nas instalações de refino de petróleo, as falhas em materiais estão relacionadas com a corrosão, além disso, os processos de corrosão de metais são problemas no mundo, causando ônus em processos industriais e gerando situações de risco como a corrosão de pilares metálicos em pontes ou em fuselagens de aviões. Dentre os meios corrosivos, um muito comum é o meio ácido, que será o meio estudado neste trabalho. Com todos os problemas citados, se faz necessário o estudo de inibidores de corrosão com alta eficiência, estabilidade e que, preferencialmente, não agridam o meio ambiente. Alguns inibidores de corrosão apresentam solubilidade limitada em água, sendo necessária a utilização de alguns solventes não tão amigáveis ao meio ambiente. Então, propôs-se formar um complexo de inclusão para tornar possível a solubilização de inibidores convencionais em solução aquosa, como algumas tioureias, que apresentam solubilidade limitada em água. Essa completa solubilização do inibidor de corrosão orgânico em meio aquoso é possível com a utilização de um aditivo (hospedeiro) capaz de encapsular tais moléculas (convidados) via interações não covalentes, de modo a alcançar o máximo desempenho de inibição. Para a formação do complexo de inclusão foi usado como molécula hospedeira, a α e a β hidroxipropilciclodextrina e como molécula convidada a dibenziltioureia. A intenção foi testar a melhora da ação inibidora da corrosão do aço carbono em meio de HCl 1mol.L-1 com ensaios de perda de massa, de impedância, polarização e microscopia eletrônica de varredura (MEV), além de evidenciar a formação destes complexos de inclusão através da espectroscopia de absorção vibracional no infravermelho, espectroscopia de RMN de 1H, espectroscopia de absorção no Ultra-violeta e análise térmica diferencial (DTA)

真菌单宁酶发酵五倍子和有机溶剂中酶法合成没食子酸丙酯的研究

本文报告了丝状真菌单宁酶发酵五倍子及有机溶剂中酶法合成没食子酸丙酯的研究。利用单宁和/或五倍子诱导丝状真菌产生单宁 酶的原理，借助二级发酵程序，对从天然源得到的75株菌进行了生物转化实验研究。选择出既能水解单宁或五倍子成没食子酸，又 能把没食子酸和丙醇合成没食子酸丙酯，而且生物催化活性都较高的1株菌，这株菌经初步鉴定为黑曲霉(Aspergillus niger No.17)。随后对它开展了产酶条件和参数优化实验，得出了最佳培养条件。立足于参数优化实验方案的基础上，经由液体培养发酵 制备单宁酶制剂，并把该酶通过化学手段共价结合到一种新型载体—聚乙烯醇和戊二醛反应生成的缩醛上，制备得到固定化单宁酶 。这种固定化生物催化剂在两种有机介质体系中都具有逆向催化合成没食子酸丙酯的能力。最后建立起来一条有效可行的微生物酶 法制备没食子酸的技术途径，没食子酸产率达到70%。对这种物质进行元素 分析：含C,49.45%;含H,3.63%。它的熔点为237℃～243 ℃，三种溶剂系统的TLC均只给出一个斑点。这些数据都与标准品一致。有机溶剂中酶法合成没食子酸丙酯的技术途径已经建立。 水溶性单宁酶在潜溶剂体系中也能催化上述酯化反应，反应混合物中的PG浓度为16.4mmol/L，制备薄层被用于分离反应混合物所含 的PG，这种产物被红外、质谱及三种溶剂系统的TLC等方法鉴定，确证为目标产物。在这一学位论文的实验研究过程中，还包括一 些生化分析方法的建立和应用，这些方法用于鉴定底物和产物及测定它们的浓度，其内容主要包括TLC定性/半定量分析、元素分析 、质谱、红外等手段的综合运用。本工作为开发我国特有的天然产物资源—五倍子的生物化工加工技术及非水相生物催化技术的开 发，提供了有用的基础数据资料，具有应用基础研究工作的重要性。In this thesis, the studies on the fermentation of Chinese gallotannin by filamentous fungi with tannase activity and enzymatic synthesis of propyl gallate(PG) in organic solvents were described through these biocatalysts. Based on the principles of induction enzyme, the tannase produced from filamentous fungi by adding tannic acid(TA) and/or Chinese gallotannin into media was investigated, and the screening experiments of bioconversion were done with 75 strains by means of a two-stage fermentation procedure. These strains were isolated with the enrichment culture technique from natural sources. Hence we selected one strain (Aspergillus niger No.17) that can not only catalyze the hydrolyses of TA and/or Chinese gallotannin into gallic acid(GA) in the liquid cultures, but also be used to synthesize PG from propanol and GA in the non-aqueous media. At the same time both of its biocatalytical activities were higher. This strain was calssified to be Aspergillus niger by the primary identification. Then optimum conditions for production of the tannase and its parameters were examined. In this way, one set of optimum culture conditions was selected. Making use of the optimum proposal, the tanase was prepared through a liquid fermentation procedure. The enzyme was convalently coupled to a new type of carrier which was made chemically from polyvinyl alcohol(PVA)and glutaraldehyde. The immobilized enzymes were able to synthesize PG reversely in two organic media. Finally, an effective enzymatic technique for production of GA was developed. The yield of GA products was up to 70%。Element analysis for this substance: calce: C, 49.42%; H, 3.56%; found: C, 49.45%, H, 3.63%. Its melting point was 237℃～ 243℃ and TLCs on three solvent systems gave only one spot respectively. These data were identical with theauthentic GA. The enzymatic synthesis of PG in organic solvents was extablished with reverse route of tannase catalytical hydrolysis. Aqueous enzyme perparation also catalyzed above esterification in a buffer system. The PG concentration in the reaction mixture was 16.4mmol/L. The reparative-scale TLC was used to isolate PG from the reaction mixture. This product separated was identified by IR, MS and TLC on three solvent systems. In this study of thesis, some biochemical analytical mehtods were developed and used to identify substrates and products, and to determinate their concentration. These methods, including TLC qualitative/half quantitative analysis, element analysis, MS, IR and so on, were useful, available and performable. This work provided basic data and information for developing the biochemical engineering and bio-processing of Chinese gallotannin-a special natural resource in China and the non-aqueous phase biocatalysis. Thus, this study possesses importance in the applied and basic research work.

Molecularly imprinted monolithic stationary phases for liquid chromatographic separation of enantiomers and diastereomers

The method for preparation of molecularly imprinted monolithic stationary phase has been improved to achieve liquid chromatographic separation of enantiomers and diastereomers. By adopting low polar porogenic solvents of toluene and dodecanol and optimal polymerization conditions, the molecularly imprinted monolithic stationary phases with good flow-through properties and high resolution were prepared. Enantiomers of amino acid derivatives and diastereomers of cinchona alkaloids were completely resolved using the monolithic stationary phases. The influence of porogenic composition, monomer-template ratio and polymerization conditions on the chromatographic performance was investigated. Some chromatographic conditions such as the composition of the mobile phase and the temperature were characterized. Scanning electron microscopy showed that the molecularly imprinted monolithic stationary phase has a large through-pore structure to allow the mobile phase to flow through the column at very low backpressure. Accelerated separations of enantiomers and diastereomers were therefore achieved at elevated flow rates. Finally, the chiral recognition performance of the prepared stationary phase in aqueous media was investigated. Hydrophobic interaction, and ionic and/or hydrogen bonding interactions were proposed to be responsible for the recognition mechanism. (C) 2002 Elsevier Science B.V. All rights reserved.