叶酸受体介导的负载紫杉醇纳米药物输送系统的制备

目的:构建靶向肿瘤组织的药物输送系统,是解决目前临床肿瘤化疗问题的有效途径之一.我们拟开展叶酸受体介导的负载紫杉醇纳米药物输送系统的制备及其表征.方法:以丁二酰化肝素为载体,通过碳二亚胺法将叶酸和丁二酰化肝素连接,制备肝素-叶酸偶联物,然后通过物理方法将紫杉醇包裹在肝素-叶酸偶联物中,在水溶性条件下体系自组装成肝素-叶酸-紫杉醇纳米粒.应用核磁共振氢谱(1H NMR),动态光散射(DLS)和扫描电子显微镜(SEM)对构建的纳米药物结构进行表征,同时观测其在水溶性条件下的自组装行为.结果:成功制备了肝素-叶酸-紫杉醇纳米药物输送系统,检测表明药物系统带有8.5％(w/w)的叶酸并负载9.6％(w/w)的药物,SEM检测表明形成了球状的纳米颗粒,DLS表明粒子的粒径在了86 nm左右.结论:我们成功制备了叶酸受体介导的负载紫杉醇的纳米药物输送系统,在进一步开展的生物活性的检测中,希望通过叶酸受体的靶向作用,引导药物定向分布在肿瘤组织,从而提高化疗药物的治疗效果同时降低其对正常细胞的毒副作用,为开发新型靶向药物输送系统提供基础.     

聚乙二醇-聚乙烯亚胺纳米微囊介导质粒转染骨髓间质干细胞

骨髓间质干细胞基因修饰及细胞移植是再生医学领域新兴的治疗策略和研究热点. 利用非病毒基因载体聚乙二醇-聚乙烯亚胺共聚物介导质粒转染骨髓间质干细胞, 观察共聚物/质粒纳米微囊在骨髓间质干细胞的吸附、内吞以及表达效率. 结果表明, 聚乙二醇-聚乙烯亚胺纳米微囊能保护质粒免受核酸酶降解, 将质粒包裹为直径100~150 nm的微囊并吸附于骨髓间质干细胞表面, 经由细胞内吞, 转染效率约为11.7%, 比阳离子脂质体介导的转染效率高8.5%, 是用于干细胞转染的良好基因载体.     

新型可降解PEI衍生物的体外表征及在HUVEC细胞中的毒性研究

目的:以分支状PEI 1800 Da为基本单元,以化学方法连接咪唑二醛,构建含有可降解亚胺键的新型聚乙烯亚胺衍生物基因载体。对合成的新型基因载体进行体外表征,测定其与p DNA形成的复合物的粒径和zeta电位,研究该复合物在HUVEC细胞中的细胞毒性。方法:通过有机合成方法合成新型聚乙烯亚胺衍生物,考察其与p DNA形成的复合物的粒径和zeta电位,并通过透射电镜考察复合物的形态特征,通过CCK-8方法测定复合物在HUVEC细胞中的毒性。结果:合成的新型基因载体能与p DNA复合形成200 nm左右带20 m V正电荷的纳米颗粒,有利于细胞内吞;形态特征研究表明新型基因载体能将p DNA压缩成类球形的纳米粒,大小与粒径检测结果基本一致。细胞毒性实验表明,合成的新型基因载体材料在相同质量比范围内显示出明显低于PEI25 KDa的细胞毒性。结论:合成的新型基因载体具有较低的细胞毒性,是一种具有良好应用潜力的基因输送载体。     

两种阳离子纳米基因载体及植物基因介导效果的研究

以阳离子聚乙烯亚胺(polyethylenimine, PEI)和壳聚糖(chitosan, CS)作为两种植物基因载体,分别制备了载基因PEI纳米粒(PEI/DNA)和壳聚糖-DNA纳米粒(CS/DNA),并对其形态、粒度分布、包封率、DNA结合的稳定性及纳米颗粒对DNA的保护等方面进行表征.并以GFP基因为报告基因进行植物细胞转染,比较两者转化效率.结果表明PEI/DNA纳米粒稳定性,对DNA的保护以及转染效率等方面均优于壳聚糖-DNA纳米粒.     

猪β-内啡肽基因克隆和重组质粒壳聚糖修饰分子包装体外表达研究

目的克隆猪β-内啡肽基因,研究其体外原核、真核表达,探索高效表达目的基因的新型纳米材料,为进一步研究β-内啡肽对动物免疫应答和应激调节等方面的作用奠定基础。方法利用基因延伸重叠PCR克隆β-内啡肽的基因cDNA,双酶切后插入VR1020、pGEX-4T-1,构建其真核、原核表达载体;以不同浓度的IPTG诱导表达重组融合蛋白,并作SDS-PAGE和RT-PCR分析目的基因原核表达情况;利用壳聚糖及其修饰分子制备纳米颗粒包装重组真核表达质粒,体外转染HEK293细胞,提取总RNA进行RT-PCR分析β-内啡肽基因在真核细胞的表达。结果成功克隆了猪β-内啡肽基因,并构建获得其原核和真核表达载体;不同浓度的IPTG诱导后,在29.7kDa的位置出现了新的蛋白条带,而原来的26.2kDa处的GST标签蛋白条带消失。说明目的基因已经和GST融合产生了新的融合蛋白;壳聚糖及其聚乙二醇和聚乙烯亚胺接枝修饰分子(mPEG-PEI-CS)纳米颗粒包裹VREP转染HEK293细胞,48h后收集细胞,RT-PCR和ELISA检测显示VREP能够在HEK293细胞中高效地转录表达β-内啡肽。结论本实验成功克隆了猪的β-内啡肽基因,并成功进行了原核及真核细胞表达分析,壳聚糖修饰分子纳米颗粒包装可高效表达目的基因,为进一步的动物实验奠定了基础。     

空心磁性微球负载La掺杂TiO_2的制备和光催化性能

以自制的粒径均一分散P(St-AA)聚合物微球为模板,制备了P(St-AA)/Fe_2O_3纳米颗粒,热处理后获得的纳米磁性空心微球;在溶胶凝胶法制备La掺杂TiO_2方法的基础上,制备了以磁性空心微球为载体的空心磁性微球负载La掺杂TiO_2,通过紫外光催化实验表明,该产品降解亚甲基蓝的效率优于同等条件制备的La掺杂TiO_2。通过SEM、TEM对产物的形貌和微观结构进行了表征。     

纳米羟基磷灰石表面修饰及其转染细胞的研究

目的:探讨羟基磷灰石-聚乙烯亚胺(nHA-PEI 10KD)纳米颗粒的癌细胞基因转染效率.方法:通过透射电子显微镜(TEM)观察HA-PEI(10KD)纳米颗粒的形态及粒径,Zeta电位仪测定nHA-PEI和HA在酸、碱、中性环境中的电位,用琼脂糖凝胶电泳检测nHAP-PEI(10KD)与DNA结合的能力,MTT比色法检测nHAP-PEI(10KD)对nepG2细胞的毒性,选用增强型绿色荧光蛋白质粒pEGFP1与nHA-PEI结合后,分别转染真核细胞HepG2、Hela、SW620,计算其转染率.结果:nHA-PEI(10KD)分散程度好,粒径60-80nm,在PH7.2时,Zeta电位42.87mV,能转染实验中的细胞,转然效果最好的是HepG2细胞,其次Hela、SW620,转染率高于PEI(10KD)、nHA,但低于脂质体.结论:通过阳离子PEI修饰HA,可有效将增强型绿色荧光蛋白质粒转入HepG2细胞,HA-PEI(10KD)纳米颗粒复合物有望成为基因传递的有效栽体.     

巯基化壳聚糖包裹人参纳米颗粒的制备

目的:制备巯基化壳聚糖包裹的且具有良好的荧光敏感性的人参纳米颗粒.方法:采用分子嫁接法和溶剂挥发法,合成巯基化壳聚糖.利用得到的巯基化壳聚糖包裹人参纳米颗粒,制备巯基化壳聚糖人参纳米颗粒.加入对巯基敏感的荧光试剂,利用荧光显微镜对其荧光活性进行检测.结果:巯基化壳聚搪包裹的人参纳米颗粒形状规则,具有核-壳结构,湿态下平均粒径约为300nm;同时在生理pH下具有很强的荧光活性.结论:巯基化壳聚糖包裹的人参纳米颗粒具有良好的缓释作用和荧光敏感性.     

抗体和寡核苷酸双标记纳米金生物探针的制备及性能分析

基于纳米金粒子与抗体静电吸附作用,与硫醇修饰的寡核苷酸共价结合,建立一种新的双标记纳米金生物探针的制备方法.通过透射电镜（TEM）、紫外光谱、斑点免疫金渗滤法、免疫金银染色光镜观察法、荧光标记法等检测探针表征,及表面抗体活性情况和寡核苷酸的覆盖率,同时采用变性聚丙烯酰胺凝胶电泳（PAGE）检测寡核苷酸的存在.结果表明,纳米金粒子同时连接抗体和寡核苷酸后生物性能良好,且每个纳米金粒子（10±3）nm表面可覆盖寡核苷酸(92±20)条,双标记纳米金生物探针的制备具有简捷、稳定的特点.可作为一种新型探针应用于超微量蛋白质检测.     

核-壳型磁性纳米微球的制备及在核酸提取中的应用

目的:改进传统的溶胶-凝胶方法而制备得表面包裹SiOZ的核-壳型磁性纳米微球,然后将表面连有链霉亲和素的磁性纳米微球应用于生物样品中核酸的分离.方法:用透射电子显微镜(TEM)、红外光谱(FTIR),X射线衍射仪(XRD)和磁强计(VSM)对得到的纳米微球进行表征,最后用电泳验证核酸.结果:表明制备得到的磁性纳米微球表面包裹Si02,粒径均匀,分散性良好,并且具有超顺磁性和较大的比饱和磁化强度.电泳结果表明磁性微球可以很好地从细胞悬液、组织、血液等样品中分离得到高质量的核酸.结论:该方法简便快速有效,其过程不需要使用任何有毒溶剂,操作简单.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

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.