新型γ-聚谷氨酸自组装纳米胶束的制备及用于蛋白载体的研究

对水溶性的γ-聚谷氨酸(γ-PGA)进行了接枝改性,合成了两亲性γ-聚谷氨酸(γ-PGA)接枝衍生物,采用超声探头法制备胆甾醇基γ-PGA自组装胶束,并以卵清蛋白(OVA)作为模型蛋白,研究其载药和释药性能.结果表明,制备的两亲性胆甾醇基γ-PGA自组装胶束平均粒径为299.6+ 27.3nm,粒径的多分散系数较窄(0.17),且具有较低的细胞毒性;其疏水核-亲水壳的纳米微结构对蛋白药物显示了良好载药性能,对OVA载药量可达118.8 μg/mg,包封率33.5％;体外释药结果显示,负载OVA的甾醇基γ-PGA自组装胶束能延缓蛋白的释放,释药速率与介质pH密切相关.     

丝素微球的制备方法研究进展

丝素蛋白因其特殊的物理化学性质,为制备不同形态的材料提供了依据;丝素蛋白也因其良好的生物相容性、生物降解性为生物材料应用提供了重要的临床选择。本文综述了国内外学者对丝素微球的制备方法的探究,包括乳化法、喷雾干燥法、层流射流技术以及自组装方法,并比较了各种制备方法的优缺点。此外,本文还介绍了丝素微球在药物缓释领域中的应用进展,并提出了几个针对制备丝素微球亟需解决的问题。     

影响类弹性蛋白多肽自组装成微球的因素及其作用机制

影响类弹性蛋白多肽(ELPs)自组装成微球的因素较多,目前尚缺乏系统研究。以类弹性蛋白多肽[KV8F]n为对象,利用动态光散射仪测定了不同条件下其自组装成微球的粒径。结果表明:随着分子量的增加ELPs形成的微球粒径也随之增大,粒径的均一度减小;当盐浓度低于0.4 mol/L时,盐浓度的增加,微球粒径相应增加,而盐浓度高于0.4 mol/L则呈减少的趋势,但粒径均大于1.1μm;而当ELPs末端融合木聚糖酶和1,3-丙二醇氧化还原酶后,其自组装形成的微球粒径急剧减小,约为游离ELPs的1/10,分别为151.0 nm和174.2 nm。导致这种现象的原因可能是酶分子和ELPs通过静电引力相互作用后,酶分子的空间位阻妨碍了ELPs分子的聚集。     

用壳聚糖纳米磁性微球纯化血红细胞超氧化物歧化酶

本研究旨在用壳聚糖-聚丙烯酸纳米磁性微球纯化血红细胞超氧化物歧化酶。采用了接枝共聚法,以K2S2O8为引发剂,使壳聚糖(CTS)与聚丙烯酸(PAA)进行自由接枝共聚合成含有两性基团(-NH3,-COOH)的壳聚糖-聚丙烯酸纳米微球。化学共沉淀法制备Fe3O4磁流体,以戊二醛为交联剂,制备壳聚糖-聚丙烯酸纳米磁性微球。用傅里叶变换红外光谱仪对磁性微球结构进行检测。JEM-4000EX电镜技术对微球粒径,形貌进行表征。SOD试剂盒测定各步骤Cu-ZnSOD酶活性。结果表明,壳聚糖-聚丙烯酸纳米磁性微球有较好的粒径分布、磁响应性及蛋白吸附特性。纯化后酶比活性达6 727 U/mg,产品得率21.1%,活性回收85.7%。壳聚糖-聚丙烯酸纳米磁性微球经血液纯化血红细胞SOD具有可再生性、易操作性,其纯化效果取决于金属Cu2+的螯合程度。     

聚合物脂质纳米球的制备优化

目的:制备粒径均一且稳定、载药率和包埋率较高的聚合物脂质纳米球。方法:将HSPC(氢化大豆卵磷脂)与PLGA(聚乳酸-羟基乙酸共聚物)两种材料结合,利用超声复乳法制备聚合物脂质纳米球,采用响应面法优化最佳制备工艺;以HSPC(氢化大豆卵磷脂)与PLGA(聚乳酸-羟基乙酸共聚物)的比例、PVA浓度、超声功率为条件优化制备参数,以粒径为响应值。结果:优化后的最佳工艺参数为:HSPC与PLGA的比例为1:10,PVA浓度为0.66%,超声功率为51.34%(205.36 W)。结论:按最优工艺制备出的聚合物脂质纳米粒的粒径为230 nm左右,多分散系数(PDI)值为0.057,与预测值偏差较小,且粒径分布均一,可作为蛋白及多肽类药物的递送载体。     

用壳聚糖亲和磁性微球纯化血浆凝血酶的研究

通过化学共沉淀法合成纳米粒子Fe3O4磁核,以壳聚糖为包裹材料包被自制的磁核,采用乳化交联法制备了具有核-壳结构的磁性高分子微球-壳聚糖磁性微球,并偶联肝素配基得到了一种新型亲和磁性微球,应用SEM、FT-IR、XRD等对微球的粒径、形貌、结构和磁响应性进行了表征.考察了该亲和磁性微球对凝血酶的分离纯化性能,并与传统的DEAE离子交换色谱法进行了比较.结果表明,所得亲和磁性微球具有较窄的粒径分布、形状规整,粒径在50nm左右.对凝血酶一步吸附纯化获得了比活为1879.71U/mg的酶,得率85%,纯化倍数11.057,而传统柱层析法得率为72%,纯化倍数仅为5.33.制备了壳聚糖亲和磁性微球,并将磁分离技术应用于凝血酶的分离纯化,得到了较好的效果,这将对于凝血酶的纯化及生产具有一定参考价值.     

IBDV丝素蛋白/壳聚糖DNA微球疫苗的制备及免疫原性分析

为了制备传染性法氏囊病病毒(Infectious bursal disease virus,IBDV)DNA微球疫苗,并评价其免疫效果。以丝素蛋白(Silk fibroin,SF)/壳聚糖(Chitosan,CS)为壁材,IBDV的VP2/4/3 DNA疫苗为芯材,通过戊二醛和Na2SO4介导的乳化交联技术,制备出SF/CS复合微球疫苗,然后经肌肉注射14日龄非免疫鸡,2周后加强免疫一次,酶联免疫法(ELISA)定期监测鸡血清的IBDV抗体,以研究微球化疫苗的免疫原性。结果显示:戊二醛介导交联方法影响荷载DNA疫苗的活性,而Na2SO4介导的交联方法操作简单且不影响荷载DNA活性;建立了以壳聚糖浓度0.5%(pH 5.0)、丝素蛋白浓度0.6%,质粒DNA 500μg/mL溶解在2%Na2SO4溶液中的工作条件;SF-CS复合微球DNA疫苗荷载率89.14%,大小1.98μm,对DNaseⅠ的消化有保护作用。免疫后的抗IBDV血清ELISA抗体的检测显示,微球免疫组总体高于质粒疫苗免疫组(P0.05),而且SF/CS复合微球组免疫反应要略高于单纯CS包被的抗原组。研究表明,丝素蛋白/壳聚糖作为微球佐剂能提高IBDV DNA疫苗的临床免疫效果,有很好的应用前景。     

聚苯乙烯纳米塑料-植物蛋白冠的形成与特征

为探究聚苯乙烯纳米塑料-植物蛋白冠的形成过程以及蛋白冠的形成对植物可能造成的影响,本研究选用3种平均粒径为200nm不同表面修饰的聚苯乙烯纳米塑料微球和新几内亚凤仙(Impatiens hawkeri)为对象,将3种聚苯乙烯纳米塑料分别与新几内亚凤仙的叶蛋白提取物进行反应,反应时间分别为2、4、8、16、24、36 h。利用扫描电镜(scanning electron microscopy, SEM)观察其形貌变化,原子力显微镜(atomic force microscopy, AFM)进行表面粗糙度测定,使用纳米粒度和zeta电位分析仪测定水合粒径及zeta电位,液相色谱-串联质谱(liquid chromatography-tandem mass spectrometry, LC-MS/MS)鉴定蛋白冠的蛋白成分。从生物学过程、细胞组分以及分子功能3个方面对蛋白进行分类,研究不同表面修饰的纳米塑料对蛋白的吸附选择,探究聚苯乙烯纳米塑料-植物蛋白冠的形成与特征,预测蛋白冠对植物造成的可能影响。结果表明：随着反应时间增加,纳米塑料的形貌变化越发明显,表现为尺寸和粗糙度的增加和稳定性的增...     

载阿霉素PLGA纳米微球的制备及性质研究

目的:制备新型癌症化疗制剂载阿霉素(Adriamycin)、聚乳酸-羟基乙酸共聚物(PLGA)纳米微球(ADM-PLGA-NP),研究其性质及体外释药特点。方法:以聚乳酸-羟基乙酸共聚物为包封材料,阿霉素为模型药物,采用复乳蒸发法制备ADM-PLGA-NP,扫描电镜观察微球形态,激光粒度分析仪检测粒径分布,紫外分光光度法计算载药率及包封率,体外药物释放实验考察微球对ADM的缓释作用。结果:ADM-PLGA-NP外观呈球形,平均粒径约(237±12.7)nm,载药量及包封率分别为(6.42±1.67)%和(53.82±8.34)%,药物在体外缓慢释放,5 d累积释放量达85%。结论:通过复乳蒸发法制备的ADM-PLGA-NP性质稳定,具有药物缓释性,有望成为一种新型的药物化疗载体。     

喷雾干燥法制备异烟肼PLA缓释微球

采用喷雾干燥法制备了异烟肼PLA缓释微球(IN-PLA-MS).首先采用球磨法制备IN微粉颗粒,平均粒径为0.161μm,然后将IN微粉超声分散于溶有PLA的二氯甲烷溶液中(S/O),将制备的混悬液进行喷雾干燥.制备得到的微球形态圆整光滑,无粘连,分散性好,平均粒径为5.62μm,粒径均一;体外释放试验中,IN-PLA-MS23天累积释放70%,且无明显突释;大鼠(Rattus norvegicus)体内考察中,采用液相色谱-质谱/质谱(LC-MS/MS)测定肺部药物浓度,微球在大鼠体内持续释药4周.该制备方法操作简单过程容易控制,采用包裹IN微粉颗粒的方法,未引入水分,一方面避免了因水分挥发在微球内部留下的空隙,另一方面抑制了药物在微球表面的迁移,有效地减少突释,达到较好的缓释效果.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.