二氧化硅及柠檬酸铝对红细胞膜结合水影响的研究

本研究应用等温吸附法和付里埃变换红外光谱技术测定了二氧化硅及柠檬酸铝对红细胞膜结合水的不同影响。结果为,二氧化硅明显降低细胞膜水化度,使膜结合水的ν_OH峰位显著红移,表明其可导致细胞膜脱水。而柠檬酸铝对二氧化硅的这一作用有明显的拮抗效应,即通过提高细胞膜的水化度,可维持细胞膜的正常“水结构”。此外,本文还论讨了二氧化硅诱发细胞膜的脱水作用对细胞中毒的意义,以及柠檬酸铝拮抗作用的机理。     

关于纳米二氧化硅毒性研究中实验方法问题的探讨

纳米二氧化硅在生产生活各个领域均有广泛的应用前景,人们暴露于纳米二氧化硅的机会越来越多,其毒性作用也受到了广泛关注。大量关于纳米二氧化硅毒性作用的研究已经开展,但目前依然没有国际公认的关于纳米材料毒性的评价标准,各个研究组因所用实验方法的不同导致研究结果相互不能比较、借鉴,甚至出现研究结论互相矛盾。本文就纳米二氧化硅毒性研究中实验方法的问题进行探讨,旨在为更科学、准确地评价纳米二氧化硅的毒性作用提供理论基础。     

综述——纳米材料与药物输递：基于介孔二氧化硅的多功能纳米药物输送体系研究进展

介孔二氧化硅因具有有序介孔结构、比表面积大、生物相容性好及表面易于修饰等特点, 在生物医药等领域显示出了极大的应用前景, 目前, 基于介孔二氧化硅的纳米药物输送体系已成为众多科研工作者研究的热点. 本文讨论了靶向修饰及成像等多功能化的介孔二氧化硅药物输送体系的研究进展, 同时详细介绍了一系列具有特定形态结构（如中空/摇铃状、纳米管等）的介孔二氧化硅基载药体系的制备、表面修饰及在其在药物输送、释放等领域的应用研究. 最后, 对目前介孔二氧化硅基药物输送体系（主要包括具有特定形态结构的介孔二氧化硅药物载体、多功能复合药物载体及可生物降解的介孔二氧化硅药物输送体系等）在实际应用中存在的问题进行了分析并对其未来的发展前景进行了展望.     

介孔纳米二氧化硅作为药物载体在癌症治疗中的应用

介孔纳米二氧化硅作为抗肿瘤药物载体,在癌症治疗上的应用越来越受到关注。介孔纳米二氧化硅不仅可实现药物的有效递送,而且可显著提高药物的生物利用度。功能化介孔纳米二氧化硅还能提高药物对肿瘤细胞的靶向性,实现药物的特异性按需释放。该新型纳米载体在癌症治疗中具有非常广阔的应用前景。本文对介孔纳米二氧化硅作为药物载体在多种癌症治疗中的应用,以及不同表面修饰物对药物载体递送的影响和优势加以综述,并对功能化介孔纳米二氧化硅载体对提高药物抗癌活性和靶向性的积极作用提出了展望。     

改性二氧化硅/纳米银微粒的制备及其抗菌性能分析

本文研究了改性二氧化硅包裹纳米银微粒的制备及其形貌的表征分析,通过扫描电镜表征得改性二氧化硅/纳米银微球的形貌规整,粒径主要分布于250 nm～400 nm之间。其次,通过抑菌圈实验测试了改性二氧化硅/纳米银微球对大肠杆菌和金黄色葡萄球菌的抑菌圈大小为18. 5mm和17. 8 mm。此外,将改性二氧化硅添加到人造大理石中,添加量为1. 0%时,其抗菌活性值达3. 0以上。     

介孔二氧化硅在药物递送系统中的研究进展

近年来,介孔二氧化硅作为药物载体已成为国内外的研究热点之一,主要归因于其比表面积和孔容较大、表面易修饰、生物相容性好。本文中,笔者综述了多种介孔二氧化硅药物递送系统,探讨了其性能对药物递送效率的影响,并总结了近年来基于介孔二氧化硅的刺激响应性药物递送系统以及其生物安全方面的研究进展。     

介孔二氧化硅在肿瘤治疗领域的研究进展

介孔二氧化硅纳米粒子(Mesoporous Silica Nanoparticles,MSNs)因其具有独特介孔结构、良好的生物相容性、较大的比表面积及明确的表面性质,在生物医学领域备受关注。基于介孔二氧化硅纳米粒子的药物递送系统已成为众多科研工作者研究的热点。讨论了介孔二氧化硅纳米粒子与多肽、抗体以及抗体片段、核酸适体、免疫治疗应用相结合后在肿瘤治疗领域的局限性和挑战。最后,对目前介孔二氧化硅药物输送体系在实际应用中存在的问题进行了分析,并对其未来的发展前景进行了展望。     

抗体在二氧化硅表面固定及活性测定

应用分子自组装技术,通过表面羟基化、氨基硅烷化和对苯二甲醛组装,在二氧化硅表面衍生活泼的醛基基团。利用抗体的氨基和醛基发生还原胺化反应将抗体固定在二氧化硅表面,通过抗原抗体反应定性检测固定抗体的生物活性。结果显示应用这种方法能够有效将抗体固定在二氧化硅表面,并保持抗体生物活性,该固定方法在蛋白质检测、分析和蛋白质芯片中有广泛应用价值。     

中性粒细胞胞外诱捕网在矽肺中的作用研究

目的:通过构建二氧化硅诱导动物矽肺模型,探讨中性粒细胞胞外诱捕网(neutrophil nxtracellular traps,NETs)在矽肺中可能的作用。方法:将C57BL/6J雄性小鼠完全随机分为磷酸盐缓冲液(phosphate buffered solution,PBS)组、脱氧核糖核酸酶Ⅰ(deoxyribonuclease Ⅰ, DNase Ⅰ)组、二氧化硅+PBS组、二氧化硅+DNase Ⅰ组。通过气管内滴注二氧化硅(0.2 g/kg)混悬液构建小鼠矽肺模型,PBS组与DNase Ⅰ组注入等体积的PBS。在二氧化硅(silicon dioxide,SiO_2)混悬液注入后的第0小时、10小时小鼠气管内注入DNase Ⅰ(5 mg/kg),以后DNase Ⅰ持续给药:5 mg/kg/day,直到SiO_2混悬液注入后的28天。二氧化硅(SiO_2)干预28天后,取各组小鼠肺组织与肺泡灌洗液,通过PicoGreen荧光染料检测支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF)中NETs水平,酶联免疫吸附实验(enzyme-linked immunosorbent assay, ELISA)检测BALF中转化生长因子β1 (transforming growth factor-β1,TGF-β1)与炎症因子白细胞介素6(interleukin-6,IL-6)、白细胞介素1β(interleukin-1β,IL-1β)、肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)水平,HE染色和Masson染色观察肺组织的病理学变化,Western Blot检测肺组织中NETs特异性组分瓜氨酸化组蛋白3(citrullinated-histone3,Cit-H3)表达。结果:SiO_2干预28天后,与PBS组相比,二氧化硅+PBS组小鼠肺组织炎症损伤加重,BALF中促炎介质IL-1β、IL-6、TNF-α水平上升;肺组织发生纤维化,大量硅结节形成;肺组织中Cit-H3蛋白表达量增加,BALF中NETs水平显著升高。予以NETs抑制剂DNase Ⅰ进行干预后,肺组织NETs水平显著下降,二氧化硅诱导的肺部炎症损伤、纤维化显著减轻。结论:NETs水平升高可能介导了二氧化硅诱导的小鼠矽肺模型肺部炎症损伤与纤维化。     

不同方法处理的纯氧化铝瓷贴面粘接强度的研究

目的:观察喷砂、酸蚀、二氧化硅水溶胶热处理等表面处理方法对纯氧化铝陶瓷贴面与树脂之间粘接强度的影响。方法:选择高纯α-Al2O3烧结的纯氧化铝陶瓷贴面样本30个,将其随机分为A、B、C三组,每组10个。分别应用不同的表面处理方法与同一种树脂进行粘结,A组采用单纯喷砂,B组采用喷砂+二氧化硅表面处理+HF,C组采用喷砂+二氧化硅表面处理+硅烷偶联剂,检测和比较各组的粘接强度。结果:C组的粘接强度最大,为23.84±0.74,明显高于A组和B组(P<0.05),而A组和B组的粘接强度比较差异无统计学意义(P>0.05)。结论:单纯喷砂或二氧化硅水溶胶热处理与HF的联合使用对纯氧化铝陶瓷贴面与树脂之间的粘接强度无明显改善,而采用喷砂以及二氧化硅水溶胶热处理与硅烷偶联剂的联合应用可取得纯氧化铝陶瓷贴面与树脂间的最大粘接效果。     

Localization of the binding sites for the Ricinus communis, Agaricus bisporus and wheat germ lectins on human erythrocyte membranes.

Freeze-etch electron microscopy has been utilized to localize the binding sites for the Ricinus communis, Agaricus bisporus and wheat germ lectins on human erythrocyte membranes and to determine the relation of these different glycoprotein receptors to the intramembranous particles. A. bisporus lectin, which could be visualized directly on the surface of erythrocyte membranes, and ferritin conjugates of wheat germ agglutinin showed a distribution that correlates exactly with the intramembranous particles at all lectin concentrations tested. The binding sites for both of these lectins are located on the major sialoglycoprotein of the membrane. The R. communis agglutinin-ferritin conjugate which binds to receptors on membrane glycoproteins that are distinct from the major sialoglycoprotein showed a close correlation with the intramembranous particles at low lectin concentrations and a poor correlation at high lectin concentrations. High concentrations resulted in virtually complete coating of the surface of trypsinized ghosts which displayed marked aggregation of the intramembranous particles. We conclude that the intramembranous particles of erythrocyte membranes contain at least two glycoproteins and that some membrane lectin receptors are not associated with the intramembranous particles.     

Localization of the binding sites for the Ricinus communis, Agaricus bisporus and wheat germ lectins on human erythrocyte membranes

Freeze-etch electron microscopy has been utilized to localize the binding sites for the Ricinus communis, Agaricus bisporus and wheat germ lectins on human erythrocyte membranes and to determine the relation of these different glycoprotein receptors to the intramembranous particles. A. bisporus lectin, which could be visualized directly on the surface of erythrocyte membranes, and ferritin conjugates of wheat germ agglutinin showed a distribution that correlates exactly with the intramembranous particles at all lectin concentrations tested. The binding sites for both of these lectins are located on the major sialoglycoprotein of the membrane. The R. communis agglutinin-ferritin conjugate which binds to receptors on membrane glycoproteins that are distinct from the major sialoglycoprotein showed a close correlation with the intramembranous particles at low lectin concentrations and a poor correlation at high lectin concentrations. High concentrations resulted in virtually complete coating of the surface of trypsinized ghosts which displayed marked aggregation of the intramembranous particles. We conclude that the intramembranous particles of erythrocyte membranes contain at least two glycoproteins and that some membrane lectin receptors are not associated with the intramembranous particles.     

Intramembranous particles on freeze-fractured membrane replica and sulfhydryl groups

Summary The correlated distribution of intramembranous particles and sulfhydryl groups was examined in normal adult rabbit erythrocyte ghosts. Ghosts were treated to exhibit characteristic patterns of particle distribution and sulfhydryl groups were stained with Fast Blue BBN. It was shown that particles and sulfhydryl groups were located in corresponding patterns. The results indicate that the intramembranous particles in the erythrocyte membrane consist predominantly of protein.Supported by grants from the Japanese Government, Nos. 244016 and 337001     

Intramembranous particles on freeze-fractured membrane replica and sulfhydryl groups

The correlated distribution of intramembranous particles and sulfhydryl groups was examined in normal adult rabbit erythrocyte ghosts. Ghosts were treated to exhibit characteristic patterns of particle distribution and sulfhydryl groups were stained with Fast Blue BBN. It was shown that particles and sulfhydryl groups were located in corresponding patterns. The results indicate that the intramembranous particles in the erythrocyte membrane consist predominantly of protein.     

The protective effects of lidocaine on human erythrocytes stored for seven days at 04 degrees C

Erythrocyte storage may result in cell damage due to an alteration of membrane integrity, which results in potassium efflux and hemolysis. Lidocaine has been shown to protect erythrocytes from oxidative stress by a possible membrane effect. We conducted this study to examine the effects of lidocaine on human erythrocyte storage. Erythrocytes were kept for seven days at 04 degrees C in the absence or in presence of plasma, and of lidocaine at 36.9 and 221.6 microM. Cell damage was assessed by measuring potassium efflux in the supernatant after seven days, and studying potassium efflux and hemolysis induced by oxidative stress. As expected, erythrocyte storage in the presence of plasma was less deleterious. Lidocaine decreased potassium efflux after 7 days' storage. Resistance toward oxidative stress was greater when the erythrocytes had been kept in the presence of plasma. Considering that lidocaine is widely used in various clinical situations, this data may be of clinical relevance.     

Tannic acid improves the visualization of the human erythrocyte membrane skeleton by freeze-etching

The effect of fixatives on the membrane skeleton underlying the human erythrocyte membrane was examined by freeze-etching. An anastomosing fibrillar network was readily observed on the protoplasmic surface of the erythrocyte membrane treated with tannic acid. Such structure was much less defined in unfixed membrane or membrane fixed with glutaraldehyde or glutaraldehyde followed by osmium tetraoxide. Tannic acid caused a marked increase in diameter of the fibrillar components of the membrane skeleton and of the protoplasmic surface particles of inside-out vesicles prepared by alkali treatment but did not affect the size of intramembranous particles seen on fracture faces nor the appearance of exoplasmic surfaces. The improved visualization of the membrane skeleton after treatment with tannic acid resulted from interactions between tannic acid and exposed membrane proteins.     

Receptor distribution and the mechanism of enhanced erythrocyte agglutination by soybean agglutinin

We have examined the role of receptor clustering in intact erythrocyte membranes exhibiting enhanced lectin-mediated cell agglutination by analyzing freeze-fracture and freeze-etch images of human erythrocytes labeled with ferritin-conjugated soybean agglutinin. We find that trypsinization and fixation of intact erythrocytes, in either order, causes no alteration of the random distribution of ferritin-conjugated soybean agglutinin on the surfaces of these cells as compared to their distribution on the surfaces of fixed erythrocytes and untreated erythrocyte ghosts. Furthermore, clustering of the intramembranous particles in the membrane of intact erythrocytes was not found with any of the cells described above.We conclude that clustering of the soybean agglutinin receptors is not a major factor involved in the enhanced agglutination of intact trypsinized erythrocytes. Caution is necessary in transferring information obtained with erythrocyte ghosts, where clustering can be induced, to intact erythrocytes.     

Effects of amphotericin B and its methyl ester on plasma membranes of Candida albicans and erythrocytes as examined by freeze-fracture electron microscopy

Freeze-fracture electron microscopy of the plasma membranes of Candida albicans yeast cells and red blood cells treated with amphotericin methyl ester and amphotericin B showed that amphotericin B (50 micrograms ml-1) caused extreme aggregation of intramembranous particles on the protoplasmic fracture face of the C. albicans membrane, and a marked reduction of the density of intramembranous particles. On the other hand, the rearrangement of intramembranous particles induced by amphotericin methyl ester (50 micrograms ml-1) produced elevations of the particle-free membrane domains toward the outside of the cells, so that the particles were aggregated in linear furrows surrounding these elevations on the protoplasmic fracture face, and the corresponding ridges on the exoplasmic fracture face. The density of intramembranous particles was greatly reduced on the protoplasmic fracture face. Both polyenes produced only small changes in the erythrocyte membranes at the same concentration. These results suggest that amphotericin methyl ester affects the ergosterol-containing membranes more than amphotericin B, and that ergosterol has a higher sensitivity for these two polyene antibiotics than cholesterol.     

Localization of globoside and Forssman glycolipids on erythrocyte membranes

Using the freeze-etch technique, the membrane localization of globoside, a principal glycolipid in human erythrocytes, and Forssman antigen, the chief glycolipid in sheep erythrocytes was evaluated using ferritin and colloidal gold as morphological markers for rabbit antibodies prepared against these glycolipids. Brief trypsinization of human red cell ghosts markedly aggregated intramembranous particles and permitted labeling of globoside, which appeared in a clustered arrangement. The aggregates of ferritin-anti-globoside differed from those of ferritin-wheat germ agglutinin, a label for glycophorin, which corresponded with the aggregates of intramembranous particles. Double-labeling of human trypsinized ghosts with anti-globoside/ Staphylococcal protein A-colloidal gold and ferritin-wheat germ agglutinin indicated that the patterns of labeling were different and that the aggregates of globoside did not bear a direct relationship to the intramembranous particles, which represent transmembrane proteins. Resealed sheep erythrocyte ghosts labeled with ferritin-conjugated rabbit anti-Forssman showed small clusters of Forssman glycolipid on the erythrocyte surface, which could be markedly aggregated with a second goat anti-rabbit antibody, indicating relative mobility of the small glycolipid domains. The distribution of ferritin-anti-Forssman label in sheep ghosts treated at pH 5.5 to aggregate intramembranous particles also did not show definite correspondence between intramembranous particles and the clusters of ferritin-anti-Forssman.     

Genistein abrogates pre-hemolytic and oxidative stress damage induced by 2,2'-Azobis (Amidinopropane)

The pre-hemolytic mechanism induced by free radicals initiated from water-soluble 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH) and its reversal by genistein was investigated in human erythrocytes. The time course of K+ efflux compared to the occurrence of hemolysis suggests that AAPH-induced hemolysis occurs indirectly via pore formation and band 3 oxidation as expected. However, genistein inhibited hemolysis, LDH release and membrane protein oxidation but not K+ efflux. This indicated that erythrocyte protein oxidation possibly in the hydrophobic core plays a significant role in the membrane pre-hemolytic damage. Chemiluminescence (CL) analysis carried out in non-lysed erythrocytes treated with AAPH showed a dramatic increase in CL indicating both reduced levels of antioxidants and increased membrane lipid peroxide. The V0 value was also increased up to 6 times, denoting a high degree of membrane peroxidation very early in erythrocyte membrane damage. The whole process was inhibited by genistein in a dose-dependent manner. These results indicate that the genistein inhibited both hemolysis and pre-hemolytic damage and also hindered membrane lipid peroxide formation and protein oxidation. In addition, it is suggested that pre-hemolytic damage is mediated mainly by the oxidation of both phospholipid and protein located in the deeper hydrophobic region of the membrane.