共查询到20条相似文献，搜索用时 687 毫秒
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In this paper, we study characteristics of polymers (methylcellulose, hypromellose ((hydroxypropyl)methyl cellulose), poly(vinylpyrrolidone), and poly(vinyl alcohol)) with different chemical structures for microchip electrophoresis of non-denatured protein samples in a plastic microchip made of poly(methyl methacrylate) (PMMA). Coating efficiency of these polymers for controlling protein adsorption onto the channel surface of the plastic microchip, wettability of the PMMA surface, and electroosmotic flow in the PMMA microchannels in the presence of these polymers were compared. Also relative electrophoretic mobility of protein samples in solutions of these polymers was studied. We showed that when using low polymer concentrations (lower than the polymer entanglement point) where the sieving effect is substantially negligible, the interaction of the samples with the polymer affected the electrophoretic mobility of the samples. This effect can be used for achieving better resolution in microchip electrophoresis of protein samples. 相似文献
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Hierarchically porous monoliths based on copper (Cu), cobalt (Co) and manganese (Mn) oxides with three-dimensionally (3D) interconnected macropores and open nanopores were prepared using metal bromides as precursors via a sol–gel process accompanied by phase separation. The difficulty of gelation for low-valence metal cation was overcome by introducing a highly electronegative Br atom near to the metal atom to control the rates of hydrolysis and polycondensation. The 3D interconnected macropores were obtained using appropriate polymers to induce phase separation. The domain sizes of macropores and skeletons can be controlled by reaction parameters such as concentration and/or average molecular weight of polymers, and the amount of hydrochloric acid. The crystalline metal oxide monoliths with their 3D interconnected macroporous structure preserved were obtained after heat treatment in air. 相似文献
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脂肪族聚酯是最重要的一类可生物降解聚合物，其合成过程中多采用含金属元素的催化剂，残留的金属元素会对其生物相容性和环境相容性造成不利的影响，因而，采用无毒的非金属催化剂成为脂肪族聚酯合成中备受关注的课题。本文对非金属催化剂催化合成脂肪族聚酯的研究进展进行综述。 相似文献
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PLASMA HYDROPHILIZATION AND SUBSEQUENT HYDROPHOBIC RECOVERY ARE STUDIED FOR TEN DIFFERENT POLYMERS OF MICROFABRICATION INTEREST: polydimethylsiloxane (PDMS), polymethylmethacrylate, polycarbonate, polyethylene, polypropylene, polystyrene, epoxy polymer SU-8, hybrid polymer ORMOCOMP, polycaprolactone, and polycaprolactone/D,L-lactide (P(CL/DLLA)). All polymers are treated identically with oxygen and nitrogen plasmas, in order to make comparisons between polymers as easy as possible. The primary measured parameter is the contact angle, which was measured on all polymers for more than 100 days in order to determine the kinetics of the hydrophobic recovery for both dry stored and rewashed samples. Clear differences and trends are observed both between different polymers and between different plasma parameters. 相似文献
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We experimentally demonstrate that addition of small, charge-neutral polymers to a buffer solution can promote compression of dilute solutions of single electrophoresing DNA. This phenomenon contrasts with the observed extension of DNA during capillary electrophoresis in dilute solutions of high molecular weight polymers. We propose these discrepancies in micron-scale DNA configurations arise from different nano-scale DNA-polymer collision events, controlled by solute polymer properties. We build upon theories previously proposed for intermolecular DNA aggregation in polymer-free solutions to develop scaling theories that describe trends seen in our data for intramolecular DNA compaction in dilute polymer solutions. 相似文献
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J. B. Varuna Kumara N. R. Ravikumara Basavaraj Madhusudhan 《Indian journal of clinical biochemistry : IJCB》2016,31(4):390-401
Folic acid is used for preventing and treating multiple diseases and disorders, administered in the form of oral supplements. The present research work was aimed to study the influence of two non-ionic surfactants Poloxamer and Tween 80 (Polysorbate 80) on pectin submicrospheres formulations. Typical natural polymer pectin was used to encapsulate folic acid by cross linking method. The resultant submicrospheres contributed to improve the aqueous solubility to enhance the bioavailability of folic acid. During investigation, it was observed that pectin polymers influenced kinetics of the rate of reaction more intensively than the surfactants. The physical phenomenon caused the change in their size, shape and chemistry of pectin polymers transforming into submicrospheres in aqueous condition. The characteristic differences of submicrospheres were assessed by scanning electron microscopy, differential scanning calorimetry and Fourier-transform infrared spectroscopy. The average diameters of the submicrospheres ranged between 250 and 500 nm. The encapsulation efficiency of submicrospheres ranged between 80 and 96 %. The characteristic swelling behavior of lyophilized submicrospheres was influenced by the ratio of pectin polymers and folic acid used in the formulations. The submicrospheres systems exhibited controlled release of folic acid due to the pH-dependent solubility of pectin polymers in aqueous medium. The submicrospheres showed good haemocompatibility suggesting them to be promising candidates for oral delivery. 相似文献
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以改性壳聚糖分子为基体,采用分子印迹技术合成了对有机磷农药久效磷有选择性的聚合物,并得到了相应的标准曲线。 相似文献
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详细叙述了对海藻胶和海藻胶-明胶二种不同壁膜的马拉硫磷微胶囊剂的壁膜渗透率的测定方法和测定结果,研究对农药活性物质的控制释放提出了有效的实现途径. 相似文献
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Materials with a negative Poisson's ratio (auxetic materials) have the fascinating property of becoming fatter when stretched. This article describes some of the consequences of this phenomenon and some of the routes for making polymers with this property. Potential applications for these materials are reviewed. 相似文献
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Huating Kong Jichao Zhang Jiang Li Jian Wang Hyun-Joon Shin Renzhong Tai Qinglong Yan Kai Xia Jun Hu Lihua Wang Ying Zhu Chunhai Fan 《国家科学评论(英文版)》2020,7(7):1218
Spatial resolution defines the physical limit of microscopes for probing biomolecular localization and interactions in cells. Whereas synchrotron-based X-ray microscopy (XRM) represents a unique approach for imaging a whole cell with nanoscale resolution due to its intrinsic nanoscale resolution and great penetration ability, existing approaches to label biomolecules rely on the use of exogenous tags that are multi-step and error-prone. Here, we repurpose engineered peroxidases as genetically encoded X-ray-sensitive tags (GXET) for site-specific labeling of protein-of-interest in mammalian cells. We find that 3,3′-diaminobenzidine (DAB) polymers that are in-situ catalytically formed by fusion-expressed peroxidases are visible under XRM. Using this new tag, we imaged the protein location associated with the alteration of a DNA-methylation pathway with an ultra-high resolution of 30 nanometers. Importantly, the excellent energy resolution of XRM enables multicolor imaging using different peroxidase tags. The development of GXET enlightens the way to nanoscopic imaging for biological studies. 相似文献
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S.R Holding 《Endeavour》1984,8(1):17-20
Gel permeation chromatography is the most valuable single technique in the molecular weight characterisation of polymers. The power of this technique lies in its ability to give information on the whole molecular weight distribution. In Britain, the Polymer Supply and Characterisation Centre provides a GPC service for research workers in the polymer field. 相似文献
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Understanding the influence of polymer grafted bilayers on the physicomechanical properties of lipid membranes is important while developing liposomal based drug delivery systems. The melting characteristics and bending moduli of polymer grafted bilayers are investigated using dissipative particle dynamics simulations as a function of the amount of grafted polymer and lipid tail length. Simulations are carried out using a modified Andersen barostat, whereby the membrane is maintained in a tensionless state. For lipids made up of four to six tail beads, the transition from the low temperature L(β) phase to the L(α) phase is lowered only above a grafting fraction of G(f)=0.12 for polymers made up of 20 beads. Below G(f)=0.12 small changes are observed only for the HT(4) bilayer. The bending modulus of the bilayers is obtained as a function of G(f) from a Fourier analysis of the height fluctuations. Using the theory developed by Marsh et al. [Biochim. Biophys. Acta 1615, 33 (2003)] for polymer grafted membranes, the contributions to the bending modulus due to changes arising from the grafted polymer and bilayer thinning are partitioned. The contributions to the changes in κ from bilayer thinning were found to lie within 11% for the lipids with four to six tail beads, increasing to 15% for the lipids containing nine tail beads. The changes in the area stretch modulus were also assessed and were found to have a small influence on the overall contribution from membrane thinning. The increase in the area per head group of the lipids was found to be consistent with the scalings predicted by self-consistent mean field results. 相似文献
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The global demand for data storage is currently outpacing the world''s storage capabilities. DNA, the carrier of natural genetic information, offers a stable, resource- and energy-efficient and sustainable data storage solution. In this review, we summarize the fundamental theory, research history, and technical challenges of DNA storage. From a quantitative perspective, we evaluate the prospect of DNA, and organic polymers in general, as a novel class of data storage medium. 相似文献