Attempt to visualize terminal structure on a specific facet in polymer–metal complex nanocrystals

We have successfully visualized the surface terminal structure of polymer–metal complex [{Cu₂(μ-Br)₂(PPh₃)₂}(μ-bpy)]_n nanocrystals (NCs) using Prussian blue (PB) nanoparticles (NPs). From TEM observation and analysis of the electron beam diffraction pattern, it was found that the (010) plane had grown well, and that the terminal ends of main chains would be located on the (010) plane of the present NCs as a dangling bond. Actually, PB NPs were selectively adsorbed on the (010) plane of [{Cu₂(μ-Br)₂(PPh₃)₂}(μ-bpy)]_n NCs. This fact clearly means bipyridine ligands having a nitrogen-terminal located on the surface of the (010) plane would coordinate and bind to Fe ions in PB NPs, which would lead to a new class of polymer–metal complex NCs materials.

We have successfully visualized the surface terminal structure of polymer–metal complex [{Cu₂(μ-Br)₂(PPh₃)₂}(μ-bpy)]_n nanocrystals (NCs) using Prussian blue (PB) nanoparticles (NPs).     

Identification of a strain-specific malarial antigen exposed on the surface of Plasmodium falciparum-infected erythrocytes

We have identified strain-specific antigens with Camp and St. Lucia strains of P. falciparum of Mr approximately 285,000 and approximately 260,000, respectively. These strain-specific antigens were metabolically labeled with radioactive amino acids, indicating that they were of parasite origin rather than altered host components. These proteins had the properties of a molecule exposed on the surface of infected erythrocytes (IE). First, the proteins are accessible to lactoperoxidase-catalyzed radioiodination of IE. Second, the radioiodinated proteins were cleaved by low concentrations of trypsin (0.1 microgram/ml). Third, these antigens were immunoprecipitated after addition of immune sera to intact IE. Fourth, the strain-specific immuno-precipitation of these proteins correlated with the capacity of immune sera to block cytoadherence of IE in a strain-specific fashion. Fifth, the strain-specific antigen had detergent solubility properties (i.e., insolubility in 1% Triton X-100, solubility in 5% sodium dodecyl sulfate) similar to the variant antigen of P. knowlesi, which has been proven to be a malarial protein exposed on the erythrocyte surface.     

纯钛种植体表面改性对骨结合的影响

背景：研究表明,对种植体表面进行化学、物理、生物化学等改性,可以显著提高种植体表面的生物学活性和骨结合强度。目的：综述并比较不同纯钛表面改性方法对骨结合的影响。方法：以“纯钛、种植体、种植、种植体表面、表面改性、生物活性、生物相容性、骨结合、研究进展”为中文关键词,以“pure titanium,implants,plant,the surface of the implant,surface modification,biological activity,biocompatibility,osseointegration,research progress”为英文关键词,用计算机检索CNKI数据库、万方数据库和PubMed数据库。结果与结论：钛具有稳定的化学性能、良好的生物相容性及较高的抗断裂强度,因而在种植修复中被广泛应用,但钛种植体是一种生物惰性材料,直接植入人体后的生物相容性和生物学活性较差,影响其与骨的结合。为提高种植体骨结合强度,目前最为有效的方法是对纯钛表面进行改性。大多数研究表明,经过改性后的种植体具有一定的骨诱导作用,可促使骨细胞在其表面黏附、增殖、分化及矿化。钛种植体经过物理、化学、生物化学等改性处理后,其表面形貌、化学成分、表面粗糙度及亲水性能等发生改变,从而提高了种植体的生物相容性和生物活性,促进了骨结合的发生。     

Layer-by-layer modification effects on a nanopore's inner surface of polycarbonate track-etched membranes

The control of the morphology, as well as the physical and chemical properties, of nanopores is a key issue for many applications. Reducing pore size is important in nanopore-based sensing applications as it helps to increase sensitivity. Changes of other physical properties such as surface net charge can also modify transport selectivity of the pores. We have studied how polyelectrolyte layer-by-layer (LBL) surface modification can be used to change the characteristics of nanoporous membranes. Studies were performed with a custom made three-dimensional multilayer microfluidic device able to fit membrane samples. The device allowed us to efficiently control LBL film deposition over blank low-cost commercially available polycarbonate track-etched (PCTE) membranes. We have demonstrated pore diameter reduction and deposition of the layers inside the pores through confocal and SEM images. Posterior impedance measurement studies served to evaluate experimentally the effect of the LBL deposition on the net inner nanopore surface charge and diameter. Measurements using direct current (DC) and alternative current (AC) voltages have demonstrated contrasted behaviors depending on the number and parity of deposited opposite charge layers. PCTE membranes are originally negatively charged and results evidenced higher impedance increases for paired charge LBL depositions. Impedance decreased when an unpaired positive layer was added. These results showed a different influence on the overall ion motility due to the effect of different surface charges. Results have been fit into a model that suggested a strong dependence of nanopores'' impedance module to surface charge on conductive buffers, such as Phosphate Buffer Saline (PBS), even on relatively large nanopores. In AC significant differences between paired and unpaired charged LBL depositions tended to disappear as the total number of layers increased.

The control of the morphology, as well as the physical and chemical properties, of nanopores is a key issue for many applications.     

High efficiency blue light-emitting devices based on quantum dots with core-shell structure design and surface modification

Blue quantum dot (QD) light emitting diode (QLED) developments are far lagging behind the red and green ones as it becomes difficult to balance charge injection and photo stability than the latter. Here, we introduced a combination of a low band energy shell with better surfactants, which largely meet both abovementioned requirements. Our simulation pinpoints that it is the exposed Se on the QD surface, which causes non-radiative relaxations. By adding tributyl phosphine (TBP), which is a good ligand to Se, we recover photoluminescence quantum yield (PLQY) from less than 8.0% up to above 85.0%. The corresponding external quantum efficiency (EQE) of QLEDs increases from 3.1% to 10.1%. This demonstrates that the low bandgap shell with effective surfactant passivation is a promising strategy to enhance QLED performance.

The exposed Se on QD surface causes non-radiative relaxations which results in a low PLQY. However, the PLQY was improved from less than 8.0% up to above 85.0% by adding tributyl phosphine which can terminate the dangling bonds of the Se.     

The placental-subplacental complex: a specific indicator of placental position on ultrasound

Subplacental tissue frequently appears as a less echogenic zone adjacent to the more echogenic parenchymal texture of the placenta on gray-scale sonograms. This complex of parenchymal structures is useful in specifically localizing placental position and extent, especially in posteriorly positioned placentas, which may be shadowed by the fetus, or in cases in which focally thickened portions of the myometrium or reverberation artifact may simulate the placenta.     

一种新型纳米增透防雾膜对光学镜片的表面改性

背景:利用乙烯基双键的加聚反应原理对透明基材进行表面改性,可研制既能与光学玻璃等透明基材牢固连接,又具有高亲水性和高透光率的防雾材料。目的:通过表面改性的方法研制透光性高、防雾效果好的稳定光学防雾膜。方法:以正硅酸乙酯、乙烯基三乙氧基硅烷为基质,加入乙醇、盐酸、双蒸水,采用溶胶-凝胶法制备增透、高硬度防雾膜前体物。以前体物为基质,加入丙烯酸铵、甲基丙烯酸铵和过硫酸铵,并加入甲基丙烯酸β-羟乙酯、甲基丙烯酸甲酯等辅助官能团,采用加成聚合法制备纳米级增透、高硬度亲水防雾膜。以红外光谱分析仪、X射线衍射仪测定膜层结构,以紫外分光光度计测定镀膜前后材料的透光率,以扫描电子显微镜测量材料表面结构,并测量材料的粒径大小、膜层硬度和水接触角。结果与结论:亲水防雾膜中不仅存在Si-O-Si网状结构,还存在有机聚合亲水基团。镀膜透光率最高值为94.6%,提示该膜层具有良好的透光性。液态防雾材料粒径为(265.0±43.8)nm。水接触角为14.5°,显示为高亲水性材料。铅笔法测得膜层硬度为6H,结合度为95.1%。采用正硅酸乙酯、乙烯基三乙氧基硅烷等材料制成的Si-O-Si网状结构在乙烯基双键打开后可以连接亲水性官能团。当水滴接触防雾膜表面时会铺展开来并形成均匀的水膜,提高透光率。在保证膜层增透、高硬度的同时,还保证了光学镜片的防雾功能。该制备工艺可行性好,质量控制方法简便、可靠。     

Impact of nanoparticle surface modification on the mechanical properties of polystyrene-based nanocomposites

Nanocomposites consisting of metal oxide nanoparticles in a polymeric matrix enable the improvement of material properties and have become highly relevant for numerous applications, such as in lightweight structures with an enhanced Young''s modulus for automotive and aircraft applications. The mechanical properties can be adjusted by controlling the amount of particles, their degree of agglomeration and their direct interaction with the matrix. Whilst the latter aspect is particularly promising to achieve high reinforcement at low filler contents, the mechanisms behind this effect are still not fully understood, preventing the rational design of a particle–polymer system with customized properties. In this work, a two-step modification strategy is used to tailor the particle–matrix interface via chemical groups bound to the surface of zirconia nanoparticles. Two modifications featuring terminal vinyl functions as potentially polymerizable groups are compared. Moreover, an inert reference modification is used to determine the influence of the terminal vinylic groups. In contrast to previous studies, all groups are covalently linked to the particle surface, thereby excluding effects such as detachment or weak coordination and ensuring that changes in the mechanical properties can be correlated to chemical groups on the particle surface. After embedding modified particles in polystyrene, the mechanical properties as well as the cross-linkage between the particles and the matrix are characterized, clearly showing the significant impact of a covalent particle–matrix linkage, with an increase of the Young''s modulus by up to 28% with only 3 wt% filler content.

A two-step modification strategy is applied to tailor the particle–matrix interface in zirconia nanoparticle–polystyrene composites, achieving strongly enhanced mechanical properties.     

一种新型纳米增透防雾膜对光学镜片的表面改性

背景：利用乙烯基双键的加聚反应原理对透明基材进行表面改性,可研制既能与光学玻璃等透明基材牢固连接,又具有高亲水性和高透光率的防雾材料。目的：通过表面改性的方法研制透光性高、防雾效果好的稳定光学防雾膜。方法：以正硅酸乙酯、乙烯基三乙氧基硅烷为基质,加入乙醇、盐酸、双蒸水,采用溶胶-凝胶法制备增透、高硬度防雾膜前体物。以前体物为基质,加入丙烯酸铵、甲基丙烯酸铵和过硫酸铵,并加入甲基丙烯酸β-羟乙酯、甲基丙烯酸甲酯等辅助官能团,采用加成聚合法制备纳米级增透、高硬度亲水防雾膜。以红外光谱分析仪、X射线衍射仪测定膜层结构,以紫外分光光度计测定镀膜前后材料的透光率,以扫描电子显微镜测量材料表面结构,并测量材料的粒径大小、膜层硬度和水接触角。结果与结论：亲水防雾膜中不仅存在Si-O-Si网状结构,还存在有机聚合亲水基团。镀膜透光率最高值为94.6%,提示该膜层具有良好的透光性。液态防雾材料粒径为（265.0±43.8）nm。水接触角为14.5°,显示为高亲水性材料。＂铅笔法＂测得膜层硬度为6H,结合度为95.1%。采用正硅酸乙酯、乙烯基三乙氧基硅烷等材料制成的Si-O-Si网状结构在乙烯基双键打开后可以连接亲水性官能团。当水滴接触防雾膜表面时会铺展开来并形成均匀的水膜,提高透光率。在保证膜层增透、高硬度的同时,还保证了光学镜片的防雾功能。该制备工艺可行性好,质量控制方法简便、可靠。     

显性房室旁道对心室除极波终末向量变化的影响

目的 探讨显性房室旁道对心室除极波终末向量的影响.方法选择经射频消融(RFCA)术证实的显性单房室旁道102例及隐匿性单房室旁道38例患者,经临床常规检查元器质性心脏病.将房室旁道分为后间隔(PS)、中间隔(MS)、前间隔(AS)、左后游离壁(LP)、左前游离壁(LA)、右后游离壁(RP)及右前游离壁(RA)房室旁路.结果102例显性房室旁道患者射频消融术后终末向量全部发生改变,38例隐匿性房室旁道中的4例射频消融术后终末向量发生改变,34例无变化.显性房室旁路与隐匿性房室旁路相比差异有统计学意义(P<0.05).不同部位间的显性旁路相比差异无统计学意义(P>0.05);终末向量的变化具有导联特异性.结论显性房室旁道可以改变心室除极终末向量,并且这种变化具有导联的特异性.     

激光在组织工程生物材料表面修饰中的应用

目的:介绍激光消蚀术、激光选择性烧结和激光干涉平板印刷在组织工程生物材料表面修饰应用的背景和基本原理,并总结激光表面修饰的工作条件和特点。资料来源:应用计算机检索Medline1993-01/2006-12关于激光修饰组织工程材料的文章。检索词"laserablation,biomaterial,sintering"并限定文章的语言种类为English。同时利用计算机检索中国期刊全文数据库1994-01/2006-12的相关文章,限定文章语言种类为中文,检索词“组织工程,激光”。资料选择:对资料进行初审,纳入标准:关于3种激光表面修饰方法的应用和实验结果。排除标准:重复性研究。资料提炼:共收集到符合上述要求的文献35篇,排除5篇重复性研究。30篇符合纳入标准:其中16篇关于激光消蚀术,8篇关于激光选择性烧结,6篇关于激光干涉平板印刷术。资料综合:与传统的化学方法和其他物理手段相比,激光表面修饰具有加工精度高、无污染和不改变材料力学性质的优越性,其中有代表性的3种方法为激光消融术、激光选择性烧结和激光干涉印刷术。结论:激光表面修饰的优点是无接触加工降低污染概率,通过计算机和精密机械装置进行操控,加工精度高、结果重复性好、操作灵活;不仅能用于高分子聚合物材料,还可以用于对生物金属材料的加工。     

血管支架材料表面改性与血管内膜的增生

目的:评价血管材料改性后对血管内皮增生的影响和应用前景.方法:以"血管支架材料,表面改性,内皮增生,再狭窄,生物相容性"为中文关键词,以"biological vascular scaffold;surface modification; tunica intimal hyperplasia;restenosis;biocompatibility" 为英文关键词,采用计算机检索2008-01/2010-04相关文章.纳入有关与血管支架材料,血管支架材料改性相关的文章,排除重复研究或Meta分析类文章,以30篇为重点分析,讨论血管支架材料改性对血管内皮增生、再狭窄的影响.结果:支架植入后血管内膜的增生和再狭窄严重影响了其远期疗效,大量的动物实验和临床分析表明,血管支架材料表面改性及载药复合支架能比裸体支架能更有效解决局部慢性炎症反应、内皮功能障碍、抗凝血等问题,显示出良好的安全性和降低冠状动脉再狭窄的有效性.可降解血管组织工程支架的发展将成为新的里程碑,内皮细胞是血管组织工程中最重要的种子细胞,通过种子细胞在体外种植于生物可吸收材料的血管支架上,达到修复创伤、病变和重建功能的目的.结论:血管支架材料表面改性是目前解决支架植入后抑制内膜增生,防止血栓形成和再狭窄等问题有效方法之一.血管组织工程支架发展前景广阔.     

Enhancement of antibacterial function by incorporation of silver-doped ZnO nanocrystals onto a laser-induced graphene surface

Bacterial biofilms formed on touchable surfaces such as displays of electronic devices not only reduce the product service life, but also cause human health issues. There is an urgent need to research the biofilm formation mechanism and methodologies to prevent formation of biofilms on human touchable surfaces. It has been reported that laser-induced graphene (LIG) helps resist biofilm growth, which has been attributed to the atomic composition and sharp edges of graphene. However, LIG alone was not able to retard bacterial growth completely. It has been reported that LIG incorporated with silver (Ag) nanoparticles exhibited enhanced surface antibacterial activity. As a heavy metal, overdose of Ag is harmful to human health. Therefore, a new biocompatible antibacterial agent to replace or reduce the use of Ag is highly important. In this study, we investigate and compare the effect of LIG doped with two types of nanocrystals, i.e., ZnO and silver (Ag)-doped ZnO, on antibacterial actions. A 355 nm ultraviolet (UV) laser was used to produce LIG on a watercolor paper substrate. Formation of few-layer graphene has been verified by Raman spectra. Escherichia coli (E. coli), a representative of Gram-negative bacteria and Staphylococcus aureus (S. aureus), a representative of Gram-positive bacteria were employed for the investigation of the bacteriostatic properties of the LIG paper substrate. Results show that with the incorporation of either the ZnO nanocrystals or the silver (Ag)-doped ZnO nanocrystals into LIG, the antibacterial effect became stronger. It is further shown that the Ag-doped ZnO nanocrystals have superior antibacterial performance to that of the ZnO nanocrystals. The Ag-doped ZnO nanocrystals are potentially an effective and biocompatible antibacterial agent and yet have a much reduced and acceptable level of Ag concentration.

Ag-doped ZnO nanocrystals are incorporated into LIG for enhancing the antibacterial effect. The formulated nanocrystals act as an effective and biocompatible antibacterial agent and yet have a much reduced and acceptable level of Ag concentration.     

猪红细胞表面抗原化学修饰后应用于异种输血的初步体外研究

目的使化学修饰的猪红细胞(pRBC)呈现出与人红细胞(hRBC)相似的血清学特性,减弱或消除人体对pRBC的免疫排斥。方法采用双修饰法即rSα-GalE酶解法(100U/mL的rSα-GalE处理)修饰改造pRBC表面的Gal抗原,再用mPEG包裹法(3mmol/L的mPEG-BTC)修饰遮蔽pRBC的non-αGal表面抗原。结果修饰后的pRBC与人混合血浆的盐水交叉配血试验为阴性;修饰后pRBC的结构、功能等指标基本正常。结论经rSα-GalE和mPEG双修饰法修饰改造的pRBC呈现出与hRBC相似的血清学特性。     

表面改性对光学眼镜膜增透防雾效果的影响

背景:利用防雾材料本身的电极性,采用逐层涂膜法对光学镜片进行表面改性,以提高膜层透光和防雾性能是当前国内外研究的新热点.目的:通过表面改性的方法研制透光和防雾效果良好的光学防雾膜.方法:将聚丙烯酸、阳离子聚丙烯酰胺和硅酸钠通过逐层涂膜法构建丙烯酸/聚丙烯酰胺-硅酸钠亲水防雾膜,烘干后得到稳定的纳米膜层结构,并进行透光率、亲水性和硬度的测量.结果与结论:实验制得的防雾膜层在200 nm波长附近,其透光率高于92.9%,在波长为700～800 nm区域内,透光率达到98.1%,提示该膜层具有良好的透光性;水滴在接触膜层表面230 ms后完全分散,显示为高亲水性.制得的涂膜烘干后形成稳定的膜层结构,"铅笔法"测得硬度达到4H.因此,采用逐层涂膜法制备防雾膜方法简单,防雾性及稳定性好,提高了光学镜片的整体质量.     

Enhancing the ambient stability of few-layer black phosphorus by surface modification

Based on high-throughput density functional theory calculations, we investigated the adsorption characteristics of various elements across the Periodic Table on few-layer black phosphorus (BP). Using the criterion that the ratio of adsorption energy (E_ads) to bulk cohesive energy (E_coh) is greater than one (E_ads/E_coh > 1), we selected fifteen elements. The adsorption of these elements on few-layer BPs could significantly shift their conduction-band minimum (CBM) downward, suggesting the possibility of preventing the few-layer BPs from oxidation if the CBM can be shifted below the O₂/O₂⁻ redox potential. Our study offers an efficient approach to overcoming the technical barrier in the practical application of few-layer BPs by enhancing its ambient stability via surface modification.

To enhance the ambient stability of black phosphorus, fifteen elements have been selected to investigate their effects on the conduction band minimum of bP.     

Studies on the role of specific cell surface receptors in the removal of lipoprotein (a) in man.

The binding of 125I-lipoprotein (a) [Lp(a)] to cell surface receptors was studied on cultured human fibroblasts. The results were compared with corresponding data obtained with 125I-low density lipoproteins (LDL). Equilibrium binding studies showed that Lp(a) is bound with high affinity by the cell surface receptors. The maximum binding capacity for Lp(a) was 37% lower than for LDL. For Lp(a) and LDL, the Scatchard plots displayed linearity, indicating a single category of binding sites. Half-maximal saturation occurred at a concentration of 9.52 +/- 1.04 nM for Lp(a) and 7.76 +/- 1.29 nM for LDL. Competition binding experiments revealed that Lp(a) and LDL are nearly equally potent in competing each other for the binding sites. Binding of Lp(a) and LDL were followed by suppression of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. Cyclohexanedione treatment of Lp(a) and LDL completely abolished receptor binding. Neither Lp(a) nor LDL were specifically bound by fibroblasts obtained from a patient with homozygous familial hypercholesterolemia (FH). The removal mechanisms for Lp(a) and LDL were further compared by in vivo studies. Radioiodinated Lp(a) and LDL were injected intravenously into 12 normolipemic individuals to measure kinetic parameters of these two lipoproteins simultaneously in each subject. Mean fractional catabolic rate (FCR) of Lp(a) was 0.260 +/- 0.060 and mean FCR of LDL was 0.377 +/- 0.077 (mean +/- SD). In each subject, FCR of Lp(a) was lower than the FCR of LDL; the mean difference was 31%. The absolute synthetic rate of Lp(a) was significantly lower than the corresponding value of LDL. In each individual, the percentage of total Lp(a) that was contained in the intravascular space was higher than the corresponding value of LDL; the mean difference was 19%. A highly significant positive correlation was found between FCR of LDL and FCR of Lp(a) (r = 0.853, P less than 0.01). No relationship was found between the serum concentration of LDL-apolipoprotein B and Lp(a). The serum level of Lp(a) was positively related to the absolute rate of Lp(a) synthesis (r = 0.979, P less than 0.01). The serum level of LDL-apolipoprotein B was inversely related to FCR of LDL (r = 0.613, P less than 0.05). In a patient with homozygous FH, FCR of LDL was 0.205 and FCR of Lp(a) was 0.210. The results of these studies show that Lp(a) is specifically bound with high affinity to the same receptors of human fibroblasts as LDL. The affinity and maximum binding capacity are slightly lower for Lp(a) than for LDL. The results of the turnover studies are consistent with the assumption that Lp(a) is removed from the plasma by similar mechanisms as LDL.