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1.
采用两次乳化包埋技术制备了一种载蛋白的乳酸-乙醇酸共聚物/壳聚糖复式微球(Poly(lactide-co-glycolide)/chitosan微球,简称PLGA/chitosan微球)。先以复乳法(W/O/W)制备加载牛血清白蛋白(BSA)的PLGA微球,再以壳聚糖(Chitosan)为基体对PLGA微球进行包埋,用三聚磷酸钠(TPP)进行交联。制备中,改变内部PLGA基体的分子量制备了3种PLGA/chitosan微球以达到不同的释放动力学。采用扫描电镜(SEM)、激光粒度分析仪、傅里叶变换红外光谱法(FTIR)分别对PLGA/chitosan微球的形貌、平均粒径及表面物理化学特征进行了表征。进行了复式微球在体外的蛋白释放实验,同时检测了体外降解过程中环境pH值的变化。结果表明,PLGA/chitosan微球具有球中包埋球的复式结构。复式微球的载药率为6%~8%,微球平均粒径为40~60μm。该微球早期蛋白的突释较PLGA微球显著减少,释放周期大于75天。此外,PLGA/chitosan微球降解过程中,能维持孵育液的pH值在7~8之间,为人体可接受范围,是一种优异的蛋白缓释微球。  相似文献   

2.
以碱催化剂为媒介的转酯化反应制备生物柴油方法因其转化率高而倍受重视。该文以菜籽油为原料,在小型试验装置上,采用均相碱催化法,研究了菜籽油在碱性催化剂NaOH的作用下与甲醇经酯交换反应制备生物柴油的工艺条件。考察了醇油摩尔比(4︰1~8︰1)、催化剂用量(0.5%~2%)、反应温度(30~60℃)和反应时间(30~150 min)等工艺参数对酯交换反应的影响,对生物柴油的组成成分进行了气相色谱/质谱联用(GC-MS)分析。结果表明,在醇油摩尔比6︰1,催化剂用量为油质量的1%,反应温度为50~60℃,反应时间为60 min时,酯交换反应转化率最高可达到96.7%。该生物柴油主要由油酸甲酯、芥子酸甲酯、9,12-十八碳二烯酸甲酯、11-二十碳烯酸甲酯、亚麻酸甲酯等脂肪酸甲酯组成,其中油酸甲酯含量最高,相对质量分数高达50.30%。  相似文献   

3.
超临界CO2萃取毛竹笋油的工艺及产品成分   总被引:3,自引:4,他引:3  
为优化超临界CO2萃取毛竹笋油的工艺参数,该研究通过单因素试验和正交试验考察了萃取压力、萃取温度、萃取时间和CO2流量等因素对毛竹笋油得率的影响,并利用气质联用(GC-MS)对毛竹笋油进行成分分析。研究确定超临界CO2萃取毛竹笋油的较佳工艺为:萃取压力25 MPa、萃取温度55℃、萃取时间2.5 h和CO2流量15 L/h,较佳工艺条件下笋油得率为5.74%;GC-MS分析毛竹笋油,共鉴定出17种组分,其中β-谷甾醇、9,12-十八碳二烯酸和9,12,15-十八碳三烯酸的相对含量分别为26.00%、10.50%和9.83%。  相似文献   

4.
为提高白藜芦醇生物利用率与缓释作用,采用高压微射流法制备白藜芦醇纳米脂质体,以纳米脂质体包封率为评价指标,在单因素试验的基础上,通过二次旋转回归试验设计确定最佳制备工艺.结果表明,最佳制备工艺为卵磷脂/VE=10∶1,卵磷脂/白藜芦醇=11.6∶1,卵磷脂/胆固醇=10.5∶1,微射流压力18 366 PSI,循环次数3次.在此条件下制得白藜芦醇纳米脂质体的包封率为87.74%±1.01%,平均粒径为78.31nm±1.37nm,Zeta电位为-55.5 mV.该方法制得的白藜芦醇纳米脂质体包封率高、粒径小、分布范围窄,且体系稳定.该研究为白藜芦醇新剂型的开发及利用提供理论依据和实际指导.  相似文献   

5.
本文以2-氯-4,6-二氨-1,3,5-三嗪为虚拟模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,在纳米硅球表面合成了特异性吸附三聚氰胺的表面分子印迹聚合物(MIPs)。采用红外光谱、电镜等手段对印迹聚合物进行了表征;用静态吸附曲线和Scatchard方程评价了印迹聚合物对三聚氰胺的吸附性能。将合成的表面印迹聚合物作为填料制备分子印迹固相萃取(MIP-SPE)柱,优化了固相萃取条件,与液相色谱串联质谱联用建立了牛奶样品中三聚氰胺的MIP-SPE-HPLC/MS/MS分析方法。实验结果表明,以2-氯-4,6-二氨-1,3,5-三嗪为虚拟模板制备的MIPs能够特异性吸附三聚氰胺,其MIP-SPE柱可以富集净化牛奶样品中的三聚氰胺,添加回收率为80.9%~86.5%,相对标准偏差小于6.4%,定量限(10S/N)为0.023 mg/L。  相似文献   

6.
碳基固体酸催化剂加压催化合成生物柴油   总被引:1,自引:1,他引:0  
为了减少生物柴油制备过程中传统催化剂对环境的污染,开发新型固体催化剂具有重要意义。该文以纤维素为原料,采用碳化-磺化法制备了碳基固体酸催化剂,并利用SEM(scanning electron microscope)、BET比表面积测试法、XRD(X-ray diffraction)和NH3-TPD(NH3-temperature programmed desorption)对其结构进行表征。研究了碳基固体酸催化剂催化棕榈酸和甲醇通过酯化反应制备生物柴油的工艺条件,考察了不同醇酸摩尔比、反应时间、反应温度及催化剂用量对转化率的影响,并对比了加压条件下碳基固体酸催化剂与浓硫酸和对甲苯磺酸的催化活性。试验结果表明,当醇酸摩尔比10:1,反应温度110℃,反应时间2 h,碳基固体酸催化剂用量为棕榈酸质量的5%时,转化率可达到98.11%。在加压条件下,碳基固体酸的催化活性高于浓硫酸和对甲苯磺酸,且催化剂在使用4次后,转化率仍在60%以上。通过GC-MS分析得出制备的生物柴油甲酯质量分数为93.8%。该研究为纤维素基碳基固体酸制备生物柴油提供了依据。  相似文献   

7.
产紫青霉菌株(Penicillium purpurogenum Li-3)能定向转化甘草酸(GL)为单葡萄糖醛酸基甘草次酸(glycyrrtinic acid 3-O-mono-β-D-glucuronide,GAMG),针对课题组前期海藻酸钙包埋产紫青霉Li-3的珠体机械强度不高,操作使用性能低等问题,通过添加天然物质和化学处理改变凝胶结构,提高改性海藻酸钙珠体的机械强度,并考察了改性海藻酸钙固定化细胞的催化性质。利用改性海藻酸钙固定的产紫青霉(Penicillium purpurogenum Li-3)微球在具有隔离筛的改进型填充床反应器中连续转化甘草酸(GL)生产单葡萄糖醛酸基甘草次酸(GAMG)。结果表明添加4%的硅藻土能够改善固定化细胞微球的机械强度,提高了反应的转化率。改性前后的固定化细胞微球的最适p H值和最适温度均未发生变化,但改性的固定化细胞反应转化率与对照相比分别提高了22%和30%。向底物中添加0.12%的吐温-80能进一步使GAMG的产量提高44%。同时,改性的固定化细胞微球具有较好的贮存稳定性和重复使用性。最后利用改性固定化细胞微球在具有隔离筛的改进型填充床反应器内实现了连续生产GAMG,在最佳反应条件下,GAMG的产量为0.193 g/(L·d),GL的转化率为34%,时空产率约为13.7μmol/(L·h)。利用改性固定化细胞微球在改进型的填充床反应器内进行连续反应生产GAMG,为建立高效全细胞转化甘草酸合成GAMG的反应体系奠定了基础。  相似文献   

8.
脱硫石膏溶解产生的Ca2+会和土壤中含碳的阴离子(CO32-、HCO3-)反应,最终将CO2吸收并固定为土壤无机碳。脱硫石膏在碱土改良中的无机固碳作用对实现“碳中和”具有重要意义。以新疆阜康三工河流域的荒漠碱土为研究对象,以脱硫石膏为钙源物对0~20 cm土层进行改良。探究不同时间0~40 t?hm-2脱硫石膏施用量下土壤无机碳(SIC)和土壤无机碳密度(SICD)的变化,从而研究碱土改良中的无机固碳作用。结果表明:施用脱硫石膏能显著减轻土壤碱害(pH下降),增加土壤盐分同时具有无机固碳效果(SIC和SICD上升)(P < 0.05)。脱硫石膏最佳施用量为30 t?hm-2,此时改良土层pH降至最低(8.24)。改良后0~46d SIC含量相较对照组增加0.93 g?kg-1,SICD增加0.29 kg?m-2(即CO2固定量为1.06 kg?m-2)。改良过程中,脱硫石膏施用量与SIC、SO42-和Ca2+呈显著正相关(P < 0.05),与pH、CO32-、HCO3-和Na+呈显著负相关(P < 0.05)。气候因子对土壤无机固碳存在影响,增大相对湿度和降水量会抑制SIC含量和SICD增加,而增大风速、温度和太阳总辐射则有促进作用。研究结果为施用脱硫石膏改良碱土能增加土壤固碳潜力提供了直接证据。  相似文献   

9.
为探索钙对化学诱抗剂水杨酸(SA)、 茉莉酸甲酯(MeJA)、 龙胆酸(GA)和 -氨基丁酸(BABA)诱导番茄木质素合成的影响,在番茄六叶期用上述诱抗剂分别处理第3 叶片,然后喷施CaCl2、 蒸馏水、 乙二醇-双-(2-氨基乙醚)四乙酸(EGTA)或LaCl3,处理后0、 1、 2、 3、 5 d 测定各处理番茄第3 叶片(诱导叶)和第5 叶片(非诱导叶)中木质素含量的变化。结果表明, (1)用上述化学诱抗剂处理番茄第3 叶片,诱导叶及其上位非诱导叶中木质素含量均升高;(2)外源Ca2+ 进一步促进上述诱抗剂诱导番茄叶片中木质素含量的增加;而Ca2+ 螯合剂EGTA和质膜钙通道抑制剂LaCl3,则不同程度地抑制这些诱抗剂对木质素含量的诱导作用。这些结果表明,钙对上述4 种诱抗剂诱导番茄叶片中木质素的合成具有正调控作用。  相似文献   

10.
通过设置无机氮肥(IF)、有机氮肥(OM)、有机无机氮肥配施(IF+OM)等3个不同氮肥处理,探究长期(9年)施用不同氮肥对玉米-豇豆复种系统中土壤有机碳组分含量及官能团的影响,揭示土壤有机碳的积累规律。采用物理分组方法测定轻组颗粒有机碳(fPOC)、微团聚体内颗粒有机碳(iPOC)、微团聚体内粉黏粒有机碳(iSOC)和非闭蓄态粉黏粒有机碳(fSOC),并利用核磁共振波谱分析法测定土壤有机碳官能团结构。结果表明,与IF处理相比,OM和IF+OM处理显著提高土壤团聚体平均重量直径(MWD)和几何平均直径(GMD),且IF+OM处理下该作用更明显。相比IF处理,IF+OM处理明显提高了土壤有机碳、fPOC和iPOC的含量,但对iSOC和fSOC的含量无明显影响。与IF处理相比,IF+OM处理明显增加了烷基碳含量,但减少了芳香碳含量。路径分析表明,烷基碳/烷氧碳、疏水性、fPOC和iPOC碳含量与有机碳含量之间存在密切联系。总之,长期IF+OM有利于产量提高,增加fPOC和iPOC碳含量,优化了团聚体的结构,增强土壤稳定性,提高土壤碳固定,增加有机碳储量。  相似文献   

11.
Neutral starch microspheres (NSMs) were synthesized with epichlorohydrin as the cross-linking agent from soluble starch by inverse microemulsion method. Anionic starch microspheres (ASMs) were prepared from NSMs by the secondary polymerization with chloroacetic acid as the anionic etherifying agent. Scanning electron microscopy (SEM) revealed that microspheres had good sphericity and fine dispersibility, and the average particle size was about 75 ??m. The adsorption procedure of Cu2+, Pb2+ on ASMs was carried out by batch experiments, Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms, the adsorption equilibrium data were found to fit the Langmuir and Freundlich isotherm model, the Freundlich isotherm was more adequate than the Langmuir isotherm in simulating the adsorption isotherm of Cu2+,the adsorption of Cu2+, Pb2+ on ASMs was a spontaneous, the isosteric heat of adsorption at different adsorption levels was always negative and indicative of an exothermic process. The pseudo first- and second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The experimental data fitted well to the second-order kinetic model, which indicated that the chemical sorption was the rate-limiting step, instead of mass transfer.  相似文献   

12.
胺基化磁性壳聚糖微球对苹果渣多酚的吸附条件优化   总被引:2,自引:0,他引:2  
为分离苹果渣中的多酚物质,研究壳聚糖磁性材料对多酚物质提取的影响。采用化学共沉淀法制得Fe3O4磁核,反相悬浮交联法制得磁性壳聚糖微球,并进行胺基化改性;利用扫描电镜、激光粒度仪对微球进行表征。采用单因素试验和响应曲面法对磁性微球吸附分离苹果渣多酚的吸附条件进行了工艺优化。结果表明:胺基化磁性壳聚糖微球吸附苹果渣多酚工艺参数对多酚吸附率有显著影响,因素影响主次顺序为微球用量>摇床转速>吸附温度;胺基化磁性壳聚糖微球吸附苹果渣多酚的工艺参数为:微球用量0.25g/mL,吸附温度45℃,摇床转速127r/min,吸附率可达81.58%。壳聚糖与Fe3O4磁性物质相结合,对多酚物质具有良好的吸附性能,可以对多酚物质进行快速分离,解析后多酚得率可达78.73%。研究结果为磁性材料吸附分离多酚类物质提供了理论参考。  相似文献   

13.
An automated fluorescent microsphere-based flow cytometric triplex immunoassay, using the Luminex 100 flow analyzer with MultiAnalyte Profiling (xMAP) technology, was developed for the simultaneous detection of proteins from three vegetable sources as potential fraudulent adulterants in milk powder. In the final triplex inhibition immunoassay, soluble wheat proteins (SWP) and proteins from soy and pea were coupled to three different microsphere sets. A mixture of these microsphere sets was transferred to a microtiter plate well together with the sample and a mixture of three affinity-purified polyclonal antibodies raised against the proteins and labeled with a fluorophore (Alexa 532). After incubation for 1.5 h at room temperature in the dark, the fluorescence intensities on the microspheres were directly measured (no wash procedure) in the Luminex during 10 s per well (100 microspheres per set). The sensitivities of the three assays for plant protein extracts were determined as 0.5-0.6 microg/mL at 50% inhibition. For the detection of the vegetable proteins in milk powder, the samples were dissolved in buffer (0.1 g in 10 mL) and further diluted (20 times) to create a 50% inhibition at approximately 0.5% of the vegetable proteins in the total protein content of milk powder. With the help of calibration standards, prepared under conditions comparable to those for sample materials, the triplex immunoassay proved to be quantitative above 0.1%, although concentrations in high-heated milk powders were underestimated. Due to the xMAP technology, in which 100 different microsphere sets can be distinguished, this triplex immunoassay can easily be extended to detect other possible adulterants.  相似文献   

14.
Magnetic DEAE-GMA-EDMA microspheres were prepared via suspension polymerization and used for the immobilization of Candida rugosa lipase by ion exchange. The effect of pH values on the immobilization of lipase was investigated. Resolution of (+/-)-menthol in the hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was performed by immobilized lipase-catalyzed enantioselective esterification with propionic anhydride as acyl donor. The effects of pH condition at lipase immobilization on the conversion and enantioselectivity were investigated. As a result, pH memory of the immobilized lipase for catalyzing (+/-)-menthol resolution in the ionic liquid was observed. Better conversion and the best enantioselectivity were obtained with the immobilized lipase prepared at pH 5.0. Under the condition, (-)-menthyl propionate with enantiomeric excess of >90% was obtained. Moreover, the enantioselectivity of the immobilized lipase decreased gradually with increasing pH value.  相似文献   

15.
A controlled-release system with reduced environmental impact was produced by encapsulating the pesticide carbaryl in the waxy lipophilic material Gelucire 54/02. The microspheres were prepared by a modified hydrophobic congealable disperse-phase method. The influence of experimental parameters, such as the reciprocal ratio between the amounts of pesticide and wax employed, on size, morphology, loading efficiency, and release behavior of the particles was evaluated. Microspheres were free-flowing and showed a nonporous scaly surface at SEM analysis. The mean particle size ranged from 15.8 to 19.8 microm and was independent of the amount of Gelucire used to prepare the microspheres. At a fixed Gelucire content, the increase in theoretical carbaryl content yielded up to 72% loading efficiency, whereas at a fixed carbaryl content the increase in Gelucire amount produced a 64% increase in encapsulation efficiency. These data were accounted for by the carbaryl leakage from molten Gelucire toward the dispersing aqueous phase. The release profiles of carbaryl from microspheres showed that the use of increasing amounts of waxy material decreased the carbaryl release rate, whereas at a fixed Gelucire content, the release was the slowest when carbaryl was not completely dissolved within the matrix. The possibility to achieve different burst effects by simply varying the formulation parameters offers an efficient tool to ensure the fast release of an active dose of insecticide. The lower vertical mobility of carbaryl encapsulated in waxy microspheres compared to the vertical mobility of the technical-grade product showed that the controlled-release system has a lower potential risk for groundwater contamination.  相似文献   

16.
为充分利用中国丰富的苹果资源,开发多品类的苹果深加工产品,以磁性壳聚糖微球为吸附剂,通过磁分离技术,吸附获得苹果汁中的天然有机酸,并对其吸附过程进行研究。利用Lagergren准一级动力学方程、准二级动力学方程、Elovich方程及内扩散方程对吸附反应动力学过程进行拟合;利用Langmuir等温吸附模型、Freundlich等温吸附模型及Temkin等温吸附模型对吸附等温数据进行拟合,并对其吸附反应热力学特性进行分析。通过比较线性拟合方程的决定系数,发现磁性壳聚糖微球吸附苹果汁中有机酸的动力学过程更加符合Lagergren准二级动力学模型,吸附温度越高,吸附速率常数和初始吸附速率越大,但平衡吸附量越低。等温吸附过程更加符合Langmuir等温吸附模型,表明该吸附过程更趋向于单分子层的化学吸附。298 K时,有机酸的饱和吸附量可达到188.679 2 mg/g,表明磁性壳聚糖微球是苹果汁中有机酸的1种高效吸附剂。热力学参数ΔG°0,ΔH°0,ΔS°0,表明磁性壳聚糖微球对苹果汁有机酸的吸附过程为熵增加的可自发进行的放热过程。动力学及热力学结果为磁性壳聚糖微球吸附苹果汁有机酸的研究提供了理论基础与技术支持。  相似文献   

17.
An overview of a research on Vitis vinifera plants treated with a chemical (calcium and magnesium ions) and biological (Trichoderma viride) agents simultaneously loaded in alginate microspheres was presented. Microspheres were applied at two growth stages: before flowering and berries pea-size. Physicochemical characteristics of leaves after the two growth stages and grapes were measured in terms of bioactive components content and antioxidant activity. After the treatments, vine leaves reached a significant increase in almost all measured parameters (polyphenols, antioxidant capacity, β-carotene, and chlorophyll) compared to the control. The highest total chlorophyll content was found after the treatment with microspheres containing Mg2+/Ca2+ cations, and T. viride. The treatments enhanced Vitis vinifera leaves in terms of bioactive potential and can be further used as a functional food. As compared to the control, somewhat elevated values of total polyphenols and antioxidant activity were found on the grape samples.  相似文献   

18.
Five ethylcellulose (EC) microencapsulated formulations (MEFs) of norflurazon were prepared and applied in soil to study their mobility, dissipation, activity, and persistence. The results show that the release into water of norflurazon from EC microspheres was retarded when compared with that of commercial herbicide. The mobility of norflurazon from MEFs into soil columns has been greatly diminished in comparison with that of its current commercial formulation (CF). Norflurazon distribution at different depths in the soil was higher in the upper ring (up to 50% of the initial application). In contrast, the residues from commercial norflurazon along the complete soil column were only about 2%. Degradation and bioassay experiments showed that the MEFs had greater persistence (t1/2 values were 7.72 and 30.83 weeks for CF and MEFs, respectively) and herbicidal activity than the commercial formulation. The use of these formulations can be advantageous, because they can minimize the risk of groundwater contamination and permit herbicide use at reduced rates, maintaining the desired concentrations of herbicide in the topsoil layer for longer periods of weed control.  相似文献   

19.
Recent studies have shown that dietary polyphenols may contribute to the prevention of cardiovascular disease and cancer. Anthocyanins from different plant sources including blueberries have been shown to possess potential anticancer activities. One of the key factors needed to correctly relate the in vitro study results to human disease outcomes is information about bioavailability. The objectives of the current study were to evaluate the absorption of blueberry anthocyanin extracts using Caco-2 human intestinal cell monolayers and investigate the effects of different aglycones, sugar moieties, and chemical structure on bioavailability of different types of anthocyanins. The results of this study showed that anthocyanins from blueberries could be transported through the Caco-2 cell monolayers although the transport/absorption efficiency was relatively low compared to other aglycone polyphenols. The transport efficiency of anthocyanins averaged approximately 3-4% [less than 1% in delphinidin glucoside (Dp-glc)]. No significant difference in transport/absorption efficiency was observed among three blueberry cultivars. The observed trends among different anthocyanins generally agreed well with some published in vivo results. Dp-glc showed the lowest transport/absorption efficiency, and malvidin glucoside (Mv-glc) showed the highest transport/absorption efficiency. Our result indicates that more free hydroxyl groups and less OCH(3) groups can decrease the bioavailability of anthocyanins. In addition, cyanindin glucoside (Cy-glc) showed significantly higher transport efficiency than cyanidin galactoside (Cy-gal), and peonidin glucoside (Pn-glc) showed significantly higher transport efficiency than peonidin galactoside (Pn-gal), indicating that glucose-based anthocyanins have higher bioavailability than galactose-based anthocyanins.  相似文献   

20.
Enzymatically hydrolyzed fish protein hydrolysates could be used as a source of antioxidative nutraceuticals. In our current work, we have investigated alkali-solubilized tilapia ( Oreochromis niloticus) protein hydrolysates for their ability to scavenge reactive oxygen species (ROS) and for their reducing power. Tilapia protein isolate was prepared by an alkaline solubilization technique and used as a substrate for enzyme hydrolysis. Cryotin, protease A 'Amano' 2, protease N 'Amano', Neutrase and Flavourzyme, were used separately to determine their effectiveness in hydrolyzing tilapia protein isolate. ROS scavenging ability was quantified using an isoluminol enhanced chemiluminescent assay in the presence of a) hydrogen peroxide or b) mononuclear cells isolated from human blood. Ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) of the hydrolysates using 2, 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) or 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), were also investigated. Results showed that, in general, the TEAC, FRAP values and ROS scavenging ability of the hydrolysates increased with an increase in the degree of hydrolysis. Among the different hydrolysates, those prepared using Cryotin were most effective and Amano A2 hydrolysates were least effective in scavenging ABTS*(+) and ROS generated by hydrogen peroxide. However, FRAP assay showed that hydrolysates prepared using Flavourzyme were most effective, and Amano N and Neutrase hydrolysates were least effective in reducing ferric ions. No significant difference was observed among the hydrolysates produced with different enzymes in their ability to scavenge ROS generated by phorbol myristate acetate stimulated mononuclear cells. These results shed light on the in vitro ROS scavenging ability of alkali solubilized tilapia protein hydrolysates, as well as potential nutraceutical use of these hydrolysates.  相似文献   

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