介孔分子筛对传统药物的原位载药及缓释研究

利用原位组装法将水难溶性的治疗冠心病药物槲皮素组装进入到介孔分子筛MCM-41孔道中,重点考察了介孔分子筛对药物的原位组装率和缓释率,验证此载药体系的优势。用X射线粉末衍射仪、扫描电镜、红外光谱对组装材料进行表征。原位组装法制得的产物载药率最高达到93%[m(药物)/m(药物总量)],与后组装制得产物的组装率70%相比,有明显提高;测定体外模拟肠液中的缓释率,可知原位组装的产品释放总量约为13 h后基本不再释放,总量大概为93%,高于后组装产品(87.25%)。实验结果表明MCM-41介孔分子筛原位组装槲皮素药物分子有明显优势。     

利用SpyTag/SpyCatcher构建胞内自组装多酶复合体实现高效生物合成

SpyTagr和SpyCatche可通过自发反应形成共价键,产生稳定的分子自组装体。酶分子自组装体因具有高效有序的催化特性在合成生物学和纳米技术领域具有重要的应用价值。为探索SpyTag/SpyCatcher在大肠杆菌胞内多酶复合体系形成有序自组装分子能力,将SpyTagr和SpyCatche分别与P450BM3m单加氧酶和葡萄糖脱氢酶GDH进行融合表达,以期产生具有辅酶再生循环系统、高效生物合成靛蓝分子的SpyTag/SpyCatcher双酶自组装复合体。首先,通过电泳及质谱对重组工程菌表达蛋白进行分析,证实SpyCatcher-P450BM3m与SpyTag-GDH在胞内成功形成了自组装多酶复合体;然后,系统分析不同培养条件下组装体合成靛蓝的能力。结果发现,经0.5mmol/L IPTG诱导后,菌体在16℃继续培养18h后,工程菌对吲哚(2mmol/L)与葡萄糖(4mmol/L)的全细胞催化能力最强,靛蓝产量最高达258mg/L,是未组装多酶系统的1.9倍,比P450BM3m单酶表达系统高约2.4倍;反应70min后达到反应平衡,转化率为52%。成功实现了SpyTag/SpyCatcher介导的多酶体系在大肠杆菌细胞中的自组装和高效转化体系,为胞内多酶复合物组装体的设计提供了新思路。     

基于大样本数据的中国水稻扇型植硅体形态特征研究

水稻扇型植硅体在水稻起源研究中起着重要的作用,但由于野生稻和栽培稻扇型植硅体的区分存在不确定性,限制了扇型植硅体在早期稻作研究中的应用。本研究通过对植硅体大样本数据的统计分析得出:扇型植硅体长宽大小趋势是,普通野生稻大于栽培稻,粳稻大于籼稻;普通野生稻B/A显著大于栽培稻,粳稻B/A又显著小于籼稻。水稻扇型植硅体的长(VL)与宽(HL)呈现正相关的规律,扇型植硅体主要分布在VL<41μm和HL<39μm与VL>41μm和HL>39μm的区间内;在遗址水稻鉴定中,如发掘的扇型植硅体中多数B/A小于等于1.20就有很大可能是粳稻;如B/A大于1.2,可再根据扇型植硅体的大小区分野生稻和籼稻,多数植硅体在VL<41μm和HL<39μm的区间内可能是籼稻,在VL>41μm和HL>39μm的区间内则可能是普通野生稻。     

M.natoriense TNJL143-2菌的D-氨基酰化酶的固定化研究

D-氨基酰化酶可用于D-氨基酸的生产,本研究利用来源于Microbacterium natoriense TNJL143-2的D-氨基酰化酶,分别通过琼脂糖包埋、介孔二氧化硅MCM-41和SBA-15吸附,制备了三种固定化酶,并对三种固定化酶的固定化条件、酶学性质、活性保持时间、重复使用次数、米氏常数等参数进行了研究。结果表明,MCM-41载体固定化酶的蛋白固定率为91.6%,SBA-15载体固定化酶的蛋白固定率为88.0%,琼脂糖包埋法蛋白固定率为79.5%。MCM-41、SBA-15以及琼脂糖三种载体固定化酶最适反应pH均为7.0,最适反应温度范围均为37℃。在固定化酶的活性保持时间以及重复利用活性方面,SBA-15固定化酶同样优于其他两种固定化酶。以D型苯丙氨酸(D-Phe)为底物时,琼脂糖包埋固定化酶的Km为28.8 mol/L,SBA-15固定化酶的Km为25.9 mol/L,MCM-41固定化酶的Km为25.0 mol/L。同时本文还探索了三种固定化酶的pH使用范围及酸碱稳定性、温度使用范围及热稳定性,结果显示,SBA-15作为固定化载体均表现出较广的适用范围及较高的稳定性。在不同条件的反应体系中,SBA-15固定化酶的蛋白损失率始终小于其他两种固定化酶。     

槲皮素、松萝酸对伴放线放线杆菌产生内毒素的抑制作用研究

目的研究不同浓度下槲皮素、松萝酸对伴放线放线杆菌产生内毒素的抑制作用。方法采用显色基质鲎试验法检测不同浓度药物作用下的伴放线放线杆菌菌液中留存的内毒素量。结果槲皮素组与松萝酸组中伴放线放线杆菌菌液产生内毒素的量明显低于阴性对照组。经检验,t_(槲N)=3.890,t_(松N)=6.120,P值均<0.01,具有显著统计学差异。结论槲皮素与松萝酸对伴放线放线杆菌产生内毒素均有抑制作用,作用和效果与药物浓度呈正相关性,松萝酸的抑制作用强于槲皮素。     

中国阿魏属的黄酮体成分及其分类学意义

通过对国产阿魏属(Ferula)16个种的化学分析,发现其中13个种含黄酮体成分, 包括槲皮素、山奈酚和芹菜素的糖甙,以槲皮素成分最普遍。这些成分多为伞形科植物所常 见,与对山芹属的研究结果较接近。未发现黄酮体的三个种,即新疆阿魏、阜康阿魏和托里阿 魏,均为具有强烈臭味的药用植物。本属近前胡亚属的国产种类常为分布于半湿润山坡的高 大草本,所含黄酮体以槲皮素糖甙为主,而分布于干旱生境的种所含化合物较复杂,除槲皮素外,还含有芹菜素和山奈酚成分。本文还根据黄酮体成分对部分种的系统位置作了讨论。     

槲皮素对LPS刺激的小胶质细胞炎症因子的下调作用

探讨槲皮素对LPS刺激的小胶质细胞炎症因子的下调作用。用不同浓度的槲皮素处理细菌脂多糖(LPS)诱导过的BV2小胶质细胞,观察不同浓度的槲皮素对炎症因子:一氧化氮(NO)、肿瘤坏死因子(TNF-α绿)以及白介素-1β(IL-1β)的抑制效果。槲皮素在10μm、20μm、30μm时可降低炎症因子NO、TNF-α绿以及IL-1β的产生,与LPS组相比只加10μmol/L槲皮素处理:NO下降17.26%,IL-1β下降21.21%,TNF-α绿下降18.93%;20μmol/L槲皮素处理:NO下降45.18%,IL-1β下降35.45%,TNF-α绿下降37.77%;30μmol/L槲皮素处理:NO下降72.59%,IL-1β下降57.59%,TNF-α绿下降62.32%。但只在20μmol/L、30μmol/L槲皮素处理时与LPS组相比NO、TNF-α绿以及IL-1β的下降有统计学差异(p0.05)。与上述相同与LPS组相比槲皮素为10μmol/L、20μmol/L、30μmol/L时可降低炎症因子TNF-α绿以及IL-1βm RNA的产生,10μmol/L槲皮素处理:IL-1βmRNA下降16.88%,TNF-α绿mRNA下降14.88%;20μmol/L槲皮素处理:IL-1βmRNA下降38.96%,TNF-α绿mRNA下降37.16%;30μmol/L槲皮素处理IL-1βmRNA下降55.49%,TNF-α绿mRNA下降54.38%。但只在20μmol/L、30μmol/L槲皮素处理时TNF-α绿以及IL-1β的mRNA下降有统计学差异(p0.05)。槲皮素对LPS刺激的小胶质细胞炎症因子有一定的下调作用,其抗炎机制可能与下调NO、TNF-α绿以及IL-1β的产生有关。     

HPLC法测定芦笋茎秆中芦丁、槲皮素及白藜芦醇含量

为了建立高效液相色谱法对芦笋茎秆中芦丁、槲皮素和白藜芦醇含量的测定方法。采用不同方法提取芦笋茎秆中的芦丁、槲皮素和白藜芦醇,得出甲醇法提取芦丁、甲醇-HCl法提取槲皮素以及乙醇法提取白藜芦醇得率最高;确定了高效液相色谱法对3种物质的最佳色谱条件为流动相:芦丁为0.2 mol/L乙酸钠-甲醇(Me-OH∶H2O=35∶65)溶液(用磷酸调p H 2.80)、槲皮素为无水甲醇-0.4%磷酸溶液(55∶45,V/V),等梯度洗脱,白藜芦醇为水和甲醇,二元线性梯度洗脱;检测波长分别为:254 nm、360 nm和306 nm;流速:0.8 m L/min、1.0 m L/min、0.8 m L/min。通过该方法测得芦丁、槲皮素及白藜芦醇的平均回收率分别为:98%、97%、98%。     

槲皮素舒张大鼠离体肾动脉及其与L-型电压依赖性钙通道和蛋白激酶C的关系

为了观察槲皮素对大鼠离体肾动脉的舒张作用,并探讨该作用与蛋白激酶C(protein kinase C,PKC)的关系,本研究采用血管张力测定仪记录大鼠肾动脉肌张力变化,用膜片钳全细胞记录方式记录大鼠肾动脉血管平滑肌细胞(vascular smooth muscle cell,VSMC)L-型电压依赖性钙通道(L-type voltage-gated Ca~(2+) channels,LVGC)电流。实验结果显示,槲皮素能够舒张60 mmol/L KCl或1×10~(-5) mol/L苯肾上腺素(phenylephrine,PE)预收缩的大鼠肾动脉,其最大舒张百分比分别为(84.53±7.35)%和(76.42±4.63)%;血管内皮完整组和去内皮组肾动脉相比,槲皮素对预收缩肾动脉的最大舒张百分比没有显著性差异;预孵育PKC特异性抑制剂C6303可使槲皮素对肾动脉的最大舒张幅度降低,与未孵育C6303组相比具有统计学差异(P0.05);离体大鼠肾动脉VSMC的正常LVGC尖峰电流密度为(23.17±1.33)pA/pF,10μmol/L槲皮素可以降低其电流密度到(10.46±1.35)pA/pF,其抑制百分比为54.86%,1μmol/L C6303可部分逆转槲皮素对LVGC电流的降低幅度,其抑制百分比为62.08%(P0.05)。上述实验结果提示,槲皮素可舒张大鼠离体肾动脉,该作用具有浓度依赖性且不受内皮影响,可能与抑制LVGC和激活PKC有关。     

槲皮素与DNA的相互作用

有机小分子与DNA相互作用机理研究已经成为药物作用机理研究与新药筛选的重要手段之一。槲皮素(Quercetin)是一种多羟基黄酮类化合物,具有抗癌、抗炎、抗菌、抗病毒、降糖降压、免疫调节及保护心血管的作用。实验研究的目的是发现与确认槲皮素与DNA之间是否具有相互作用,以及确定其相互作用的类型。根据荧光光谱法和共振散射荧光光谱法的分析结果,发现槲皮素与鲱鱼精DNA之间存在相互作用;使用紫外-可见分光光度法和荧光偏振分析,发现槲皮素与鲱鱼精DNA之间的相互作用模式不属于嵌插作用,而是沟槽嵌合或者静电相互作用;最后通过分子对接实验,成功佐证槲皮素与鲱鱼精DNA之间的相互作用模式是沟槽结合。该工作有利于理解槲皮素与DNA之间的体外作用方式,助力于相应疾病的药物开发。     

Synthesis of functionalized polyethylenimine-grafted mesoporous silica spheres and the effect of side arms on lipase immobilization and application

In the present study, silicate mesoporous materials (MCM-41), MCM-41-grafted polyethylenimine (MCM-41@PEI), and succinated PEI containing amine, amide, and acid groups were successfully synthesized and characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller analysis, and X-ray photoelectron spectroscopy. Thermomyces lanuginosa lipase (TLL) was then immobilized onto MCM-41 and polymer-grafted MCM-41 by physical adsorption. Besides, for enzyme immobilization via covalent bonding, glutaraldehyde (GLU), and hexamethylene diisocyanate (HMDI) were used as the bridges for binding the enzyme to supports. The best result was obtained with the immobilized lipase on MCM-41@PEI-GLU. In the study of the enzyme reusability, it was shown that about 83% of the initial activity could be retained after 12 cycles of uses. The immobilized lipase on the selected support was also applied for the synthesis of ethyl valerate. Following 24 h incubation in n-hexane and solvent free media, the esterification percentages were 79% and 67%, respectively.     

Efficient conversion of d-glucose into d-sorbitol over MCM-41 supported Ru catalyst prepared by a formaldehyde reduction process

Ru/MCM-41 catalyst prepared by an impregnation-formaldehyde reduction method showed higher catalytic activity and sorbitol selectivity than other catalysts in the hydrogenation of glucose. SEM and XRD indicated the partial surface properties of Ru/MCM-41. Moreover, Ru dispersion and Ru surface area of Ru/MCM-41 were determined by pulse chemisorption, and the result further proved that Ru/MCM-41 had higher catalytic activity. A catalyst recycling experiment demonstrated that Ru/MCM-41 was a better catalyst and it could be reused three or four times. A speculated mechanism was proposed to illustrate the detailed process of d-glucose hydrogenation to produce sorbitol.     

Efficient conversion of d-glucose into d-sorbitol over MCM-41 supported Ru catalyst prepared by a formaldehyde reduction process

Ru/MCM-41 catalyst prepared by an impregnation–formaldehyde reduction method showed higher catalytic activity and sorbitol selectivity than other catalysts in the hydrogenation of glucose. SEM and XRD indicated the partial surface properties of Ru/MCM-41. Moreover, Ru dispersion and Ru surface area of Ru/MCM-41 were determined by pulse chemisorption, and the result further proved that Ru/MCM-41 had higher catalytic activity. A catalyst recycling experiment demonstrated that Ru/MCM-41 was a better catalyst and it could be reused three or four times. A speculated mechanism was proposed to illustrate the detailed process of d-glucose hydrogenation to produce sorbitol.     

Enrichment of phosphopeptides by Fe3+-immobilized mesoporous nanoparticles of MCM-41 for MALDI and nano-LC-MS/MS analysis

Fe3+-immobilized mesoporous molecular sieves MCM-41 with particle size of ca. 600 nm and pore size of ca. 3 nm is synthesized and applied to selectively trap and separate phosphopeptides from tryptic digest of proteins. For the capture of phosphopeptides, typically 10 microL of tryptic digest solution was first diluted to 1 mL by solution of ACN/0.1% TFA (50:50, v/v) and incubated with 10 microL of 0.1% acetic acid dispersed Fe3+-immobilized MCM-41 for 1 h under vibration. Fe3+-immobilized MCM-41 with trapped phosphopeptides was separated by centrifugation. The deposition was first washed with a volume of 300 microL of solution containing 100 mM NaCl in ACN/0.1% TFA (50:50, v/v) and followed by a volume of 300 microL of solution of 0.1% acetic acid to remove nonspecifically bound peptides. The nanoparticles with trapped phosphopeptides are mixed with 2,5-dihydroxybenzoic acid (2,5-DHB) and deposited onto the target for analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). It was found that phosphopeptides from tryptic digest of alpha-casein and beta-casein are effectively and specifically trapped on Fe3+-immobilized MCM-41 with few peptides nonspecifically adsorbed. After the extraction by Fe3+-immobilized MCM-41, the suppression to the detection of phosphopeptides caused by abundant nonphosphopeptides from tryptic digest is effectively eliminated, and the detection of phosphopeptides by MALDI is greatly enhanced with the value of signal-to-noise (S/N) increased by more than an order of magnitude. It is demonstrated that the mechanism of the adsorption of phosphopeptides on Fe3+-immobilized MCM-41 is based on the interaction between the Fe3+ and the phosphate group. Finally, Fe3+-immobilized MCM-41 is applied to extract phosphopeptides from tryptic digest of the lysate of mouse liver for phosphoproteome analysis by nano-LC-MS/MS.     

A high-sensitivity electrochemical immunosensor based on mobile crystalline material-41-polyvinyl alcohol nanocomposite and colloidal gold nanoparticles

A novel competitive immunosensor was developed as a model system using anti-human serum albumin (HSA)-conjugated gold nanoparticles (AuNPs) as an electrochemical label and mobile crystalline material-41 (MCM-41)–polyvinyl alcohol (PVA) mesoporous nanocomposite as an immobilization platform. However, no attempt has yet been made to use the MCM-41 as the supporting electrolyte for the electrosynthesis of nonconducting polymer nanocomposite. This hybrid membrane was evaluated extensively by using field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) to determine its physicochemical and electrochemical properties in immunosensor application. FESEM revealed an appropriate and stable attachment between HSA and MCM-41 and also a dense layer deposition of MCM-41–HSA–PVA film onto the electrode surfaces. DPV was developed for quantitative determination of antigen in biological samples. A decrease in DPV responses was observed with increasing concentrations of HSA in standard and real samples. In optimal conditions, this immunosensor based on MCM-41–PVA nanocomposite film could detect HSA in a high linear range (0.5–200 μg ml^?1) with a low detection limit of 1 ng ml^?1. The proposed method showed acceptable reproducibility, stability, and reliability and could also be applied to detect the other antigens.     

Catalytic activity of acetylcholinesterase immobilized on mesoporous molecular sieves

MCM-41 and FSM-16 were used for enzyme immobilization on account of their good physical and chemical properties. In this work, the catalytic activity of acetylcholinesterase (AChE) immobilized on these materials was investigated, using neostigmina as AChE inhibitor. The results show that AChE was adsorbed on MCM-41 and on FSM-16-TIPB. AChE immobilized on the latter material maintained 70% of its activity and the material did not hydrolyze ACh (as MCM-41) by itself. Therefore, FSM-16-TIPB was the best material, considering also that when neostigmine was applied to AChE immobilized on FSM-16-TIPB, the activity of AChE decreased as occurs in its free from. Hence, this model could be useful in the evaluation of different kinds of AChE inhibitors, allowing the recycling of enzymes and making possible several assays and thereby, lowering cost.     

Novel method for aroma recovery from the bioconversion of lutein to β-ionone by Trichosporon asahii using a mesoporous silicate material

In this work, we report on the synthesis and ability of the mesoporous material MCM-41 to adsorb the norisoprenoid β-ionone. This compound, with a violet aroma note, can be produced from lutein by the yeast Trichosporon asahii through a bioconversion process. We found that β-ionone inhibited the yeast growth and constrained aroma formation. Growth inhibition was overcome using silicate MCM-41 as sorbent device in a fermentation system that allowed product removal from the culture medium by headspace manipulation. Compared to a commercial silica gel, the mesoporous material exhibited a 4.5-fold higher β-ionone adsorption. Contrasting to cultures without the sorbent device, the presence of MCM-41 allowed a marked increase (14-fold) in β-ionone production. Our results suggested that confinement of the norisoprenoid into the sorbent material bypassed its toxicity which allowed a better β-ionone production. This study represents the first report on the use of MCM-41 to recover an aroma produced by fermentation and therefore, a novel application for a mesoporous material.     

Ultrasensitive electrochemical immunosensor based on Au nanoparticles dotted carbon nanotube-graphene composite and functionalized mesoporous materials

A facile and sensitive electrochemical immunosensor for detection of human chorionic gonadotrophin (hCG) was designed by using functionalized mesoporous nanoparticles as bionanolabels. To construct high-performance electrochemical immunosensor, Au nanoparticles (AuNPs) dotted carbon nanotubes (MWCNTs)-graphene composite was immobilized on the working electrode, which can increase the surface area to capture a large amount of primary antibodies (Ab(1)) as well as improve the electronic transmission rate. The as-prepared bionanolabels. composed of mesoporous silica nanoparticles (MCM-41) coated with AuNPs through thionine linking, showed good adsorption of horseradish peroxidase-labeled secondary anti-hCG antibody. Interlayer thionine was not only a bridging agent between MCM-41 and AuNPs but also an excellent electron mediator. The approach provided a good linear response range from 0.005 to 500 mIU mL(-1) with a low detection limit of 0.0026 mIU mL(-1). The immunosensor showed good precision, acceptable stability and reproducibility. Satisfactory results were obtained for determination of hCG in human serum samples. The proposed method provides a new promising platform of clinical immunoassay for other biomolecules.     

Efficient Preparation of Enantiopure D-Phenylalanine through Asymmetric Resolution Using Immobilized Phenylalanine Ammonia-Lyase from Rhodotorula glutinis JN-1 in a Recirculating Packed-Bed Reactor

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h⁻¹ and 0.32 g L⁻¹ h⁻¹, respectively. The optical purity (ee _D) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (ee _D>99%) in the scaled-up reactor reached 7.2 g L⁻¹ h⁻¹. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine.     

Electron paramagnetic resonance analyses of biotransformation reactions with cytochrome P-450 immobilized on mesoporous molecular sieves

Mobil Crystalline Material (MCM-41) can be used for the immobilization of enzymes and the investigation of electron transfer in biological systems. Electron transfer between MCM-41 with aluminum (Al-MCM-41) and cytochrome P-450 (CYP2B4) was observed using electron paramagnetic resonance (EPR). When CYP2B4 was immobilized by adsorption, it catalyzed the conversion of aniline to p-aminophenol. The electron transfer was evidenced when the signal with a g value (also called g-factor or spectroscopic manifestation of the magnetic moment) of 1.98 increased at the same time that the signal with a g value 2.24 decreased due to the addition of NADPH to CYP2B4 immobilized on Al-MCM-41, indicating that Fe^III was reduced to Fe^II. Therefore, it is possible that Al-MCM-41 participates in the electron transfer process in biological systems.