共查询到20条相似文献,搜索用时 15 毫秒
1.
Coasne B Di Renzo F Galarneau A Pellenq RJ 《Langmuir : the ACS journal of surfaces and colloids》2008,24(14):7285-7293
This paper reports a molecular simulation study on the adsorption of simple fluids (argon at 77 K) on hydroxylated silica surfaces and nanopores. The effect of surface chemistry is addressed by considering substrates with either partially or fully hydroxylated surfaces. We also investigate the effect of pore shape on adsorption and capillary condensation by comparing the results for cylindrical and hexagonal nanopores having equivalent sections (i.e., equal section areas). Due to the increase in the polarity of the surface with the density of OH groups, the adsorbed amounts for fully hydroxylated surfaces are found to be larger than those for partially hydroxylated surfaces. Both the adsorption isotherms for the cylindrical and hexagonal pores conform to the typical behavior observed in the experiments for adsorption/condensation in cylindrical nanopores MCM-41. Capillary condensation occurs through an irreversible discontinuous transition between the partially filled and the completely filled configurations, while evaporation occurs through the displacement at equilibrium of a hemispherical meniscus along the pore axis. Our data are also used to discuss the effect of surface chemistry and pore shape on the BET method. The BET surface for fully hydroxylated surfaces is much larger (by 10-20%) than the true geometrical surface. In contrast, the BET surface significantly underestimates the true surface when partially hydroxylated surfaces are considered. These results suggest that the surface chemistry and the choice of the system adsorbate/adsorbent is crucial in determining the surface area of solids using the BET method. 相似文献
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The potential of selective cell-sorption for separation/preconcentration of ultra-trace heavy metals was exploited by surface engineering of Saccharomyces cerevisiae cells. The general idea is to display the cadmium-binding peptide on the cell surface in order to enhance the covalent interaction between cadmium and the yeast cells. By immobilizing the surface-engineered yeast cells onto cytopore(?) microcarrier beads for cadmium adsorption, we demonstrated that with respect to the native yeast 600-fold and 25-1000-fold improvements were observed respectively for the tolerance of ionic strength and the tolerant capability toward various metal cations after surface engineering. Based on these observations, a novel procedure for selective cadmium preconcentration was developed with detection by graphite furnace atomic absorption spectrometry (GFAAS), employing the engineered S. cerevisiae cell-loaded cytopore(?) beads as a renewable sorption medium incorporated into a sequential injection lab-on-valve system. The cadmium retained on the yeast cell surface was eluted with a small amount of nitric acid and quantified with GFAAS. Within a range of 5-100 ng L(-1) and a sample volume of 1 mL, an enrichment factor of 30 was achieved along with a detection limit of 1.1 ng L(-1), a sampling frequency of 20 h(-1) and a precision of 3.3% RSD at 50 ng L(-1). The procedure was validated by analyzing cadmium in certified reference materials and a series of environmental water samples. 相似文献
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Weixin Huang 《中国科学:化学(英文版)》2021,(2):167-168
Surface chemistry of solids is the fundamental for processes on solid surfaces and properties of solid surfaces,such as heterogeneous catalysis,electrochemistry,corrosion,thin film growth,sensing,friction and lubrication[1].Understanding surface chemistry of solids is not only of great scientific interest,but also of important technological value for optimizing surface properties and processes.Due to the complexity of solid surface structures,it is challenging to unambiguously elucidate the surface chemistry of surface properties and processes at a molecular level. 相似文献
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Joseph K. Awino 《Supramolecular chemistry》2014,26(3-4):302-311
Amphiphilic macrocycles consisting of cholates and l-tryptophan were prepared by the copper-catalysed alkyne–azide cycloaddition. The macrocycles helped glucose permeate lipid bilayer membranes. The macrocycle with two cholates was significantly more active in the glucose transport than the one with three cholates. Inclusion of 30–50% cholesterol in the bilayer accelerated the glucose transport monotonously. The unusual cholesterol effect was explained by the hydrophobically driven pore formation, in which the associative interactions of the water molecules inside the macrocycles prompted the macrocycles to stack over one another to avoid unfavourable water–lipid hydrocarbon contact. Fluorescence quenching by water- and oil-soluble quenchers provided additional evidence for the better penetration of the dicholate macrocycle into the bilayers, consistent with the stacking model. Rigidity in the macrocycle structure was hypothesised to be the main reason for the higher transport activity and deeper membrane-penetration of the dicholate macrocycle compared with those of the tricholate. 相似文献
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William H. Fissell Anna Dubnisheva Abigail N. Eldridge Aaron J. Fleischman Andrew L. Zydney Shuvo Roy 《Journal of membrane science》2009
Silicon micromachining provides the precise control of nanoscale features that can be fundamentally enabling for miniaturized, implantable medical devices. Concerns have been raised regarding blood biocompatibility of silicon-based materials and their application to hemodialysis and hemofiltration. A high-performance ultrathin hemofiltration membrane with monodisperse slit-shaped pores was fabricated using a sacrificial oxide technique and then surface-modified with poly(ethylene glycol) (PEG). Fluid and macromolecular transport matched model predictions well. Protein adsorption, fouling, and thrombosis were significantly inhibited by the PEG. The membrane retained hydraulic permeability and molecular selectivity during a 90-h hemofiltration experiment with anticoagulated bovine whole blood. This is the first report of successful prolonged hemofiltration with a silicon nanopore membrane. The results demonstrate feasibility of renal replacement devices based on these membranes and materials. 相似文献
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Confined protein adsorption into nanopore arrays fabricated by colloidal-assisted polymer patterning
A combination of plasma surface modification of polymer thin films and colloidal nanosphere lithography was used to fabricate two-dimensional nanopore arrays as protein nanocontainers. 相似文献
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Control of interactions between nanoparticles and biosystems is essential for the effective utilization of these materials in biomedicine. A wide variety of nanoparticle surface structures have been developed for imaging, sensing, and delivery applications. In this research Highlight, we will emphasize advances in tailoring nanoparticle interfaces for implementation in nanomedicine. 相似文献
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Pore surface control of microporous coordination polymers is of great interest due to the potentially exciting functionalities it presents, such as highly selective separation, chemisorption, and novel catalysts and sensors. A discussion of our unique strategy aimed at surface engineering using metalloligands, i.e., introduction of coordinatively unsaturated metal centers, is presented. 相似文献
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Sputter etching process and reactive sputter etching process in radio frequency(RF)glow discharge for surface improvement technique of engineering plastics, especially P T F E (polytetrafluoroethylene) were studied. In the case of sputter etching in Ar gas. characteristic cone like structures were developed on the P T F E surface, resulting in improvement of adhesive property. In reactive sputter etching in H2O gas, the P T F E surface changed chemically and showed wettability. 相似文献
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The combination of biopolymer science and technology with surface engineering of paper-based cellulosic materials has a lot of potential in stepping forward to a sustainable future. Various biopolymers such as oxidized starch, carboxymethyl cellulose, and polylatic acid have been commercially used to engineer paper surface. The paper-based cellulosic products are widely used for printing/writing and packaging applications. However, the production of these products are currently dependent mainly upon the use of petroleum-based materials including synthetic pigment coating latexes and barrier coating materials. The major challenges associated with some biopolymers are their relatively high costs and unsatisfactory performances. Continuing efforts are being made to enable the increased and value-added use of various biopolymers in paper surface engineering. These polymers can be based on cellulose, hemicelluloses, chitosan, alginate, protein, polylactic acid, and polyhydroxyalkanoate. The biopolymer-engineered paper products can be tailored for use as substitutes for various non-renewable materials including plastics and metals as well. Future development in the area of biopolymers for paper surface engineering is likely to lead to new possibilities and breakthroughs, paving the way for a substantially sustainable and green future. 相似文献
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Journal of Radioanalytical and Nuclear Chemistry - Various concepts involved in the quantification of radiation dose while following the theranostic approach in nuclear medicine are outlined. The... 相似文献
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Kang M Yu S Li N Martin CR 《Langmuir : the ACS journal of surfaces and colloids》2005,21(18):8429-8438
A method for preparing a glass surface containing an ordered array of nanowells is described. These nanowell arrays are prepared via a plasma-etch method using a nanopore alumina film as the etch mask. A replica of the pore structure of the alumina mask is etched into the glass. We demonstrate that chemical information in the form of negatively charged latex nanoparticles can be selectively stored within these nanowells and not indiscriminately deposited on the surface surrounding the nanowells. To accomplish this, the chemistry of the glass surfaces within these nanowells (walls and bottoms) must be different from the chemistry of the surface surrounding the nanowells. Two different procedures were developed to make the inside vs. surrounding surface chemistries different. Atomic force microscopy (AFM) was used to image the nanowells and, via friction-force measurements, to prove that the inner nanowell surfaces can be made chemically different from the surface surrounding the nanowells. 相似文献
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This numerical study provides an error analysis of an idealized nanopore sequencing method in which ionic current measurements are used to sequence intact single‐stranded DNA in the pore, while an enzyme controls DNA motion. Examples of systematic channel errors when more than one nucleotide affects the current amplitude are detailed, which if present will persist regardless of coverage. Absent such errors, random errors associated with tracking through homopolymer regions are shown to necessitate reading known sequences (Escherichia coli K‐12) at least 140 times to achieve 99.99% accuracy (Q40). By exploiting the ability to reread each strand at each pore in an array, arbitrary positioning on an error rate versus throughput tradeoff curve is possible if systematic errors are absent, with throughput governed by the number of pores in the array and the enzyme turnover rate. 相似文献
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Chemodynamic therapy(CDT) is an emerging endogenous stimulation activated tumor treatment approach that exploiting iron-containing nanomedicine as catalyst to convert hydrogen peroxide(H_2O_2)into toxic hydroxyl radical(·OH) through Fenton reaction.Due to the unique characteristics(weak acidity and the high H_2O_2 level) of the tumor microenvironment,CDT has advantages of high selectivity and low side effect.However,as an important substrate of Fenton reaction,the endogenous H_2O_2 in tumor is still insufficient,which may be an important factor limiting the efficacy of CDT.In order to optimize CDT,various H_2O_2-generating nanomedicines that can promote the production of H_2O_2 in tumor have been designed and developed for enhanced CDT.In this review,we summarize recently developed nanomedicines based on catalytic enzymes,nanozymes,drugs,metal peroxides and bacteria.Finally,the challenges and possible development directions for further enhancing CDT are prospected. 相似文献
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Dr. Sankarprasad Bhuniya Dr. Sukhendu Maiti Dr. Eun‐Joong Kim Hyunseung Lee Prof. Jonathan L. Sessler Dr. Kwan Soo Hong Prof. Jong Seung Kim 《Angewandte Chemie (International ed. in English)》2014,53(17):4469-4474
A new theranostic strategy is described. It is based on the use of an “all in one” prodrug, namely the biotinylated piperazine‐rhodol conjugate 4 a . This conjugate, which incorporates the anticancer drug SN‐38, undergoes self‐immolative cleavage when exposed to biological thiols. This leads to the tumor‐targeted release of the active SN‐38 payload along with fluorophore 1 a . This release is made selective as the result of the biotin functionality. Fluorophore 1 a is 32‐fold more fluorescent than prodrug 4 a . It permits the delivery and release of the SN‐38 payload to be monitored easily in vitro and in vivo, as inferred from cell studies and ex vivo analyses of mice xenografts derived from HeLa cells, respectively. Prodrug 4 a also displays anticancer activity in the HeLa cell murine xenograft tumor model. On the basis of these findings we suggest that the present strategy, which combines within a single agent the key functions of targeting, release, imaging, and treatment, may have a role to play in cancer diagnosis and therapy. 相似文献
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Huabing Chen Zhanjun Gu Hongwei An Chunying Chen Jie Chen Ran Cui Siqin Chen Weihai Chen Xuesi Chen Xiaoyuan Chen Zhuo Chen Baoquan Ding Qian Dong Qin Fan Ting Fu Dayong Hou Qiao Jiang Hengte Ke Xiqun Jiang Gang Liu Suping Li Tianyu Li Zhuang Liu Guangjun Nie Muhammad Ovais Daiwen Pang Nasha Qiu Youqing Shen Huayu Tian Chao Wang Hao Wang Ziqi Wang Huaping Xu Jiang-Fei Xu Xiangliang Yang Shuang Zhu Xianchuang Zheng Xianzheng Zhang Yanbing Zhao Weihong Tan Xi Zhang Yuliang Zhao 《中国科学:化学(英文版)》2018,61(12):1503-1552
Precise nanomedicine has been extensively explored for efficient cancer imaging and targeted cancer therapy, as evidenced by a few breakthroughs in their preclinical and clinical explorations. Here, we demonstrate the recent advances of intelligent cancer nanomedicine, and discuss the comprehensive understanding of their structure-function relationship for smart and efficient cancer nanomedicine including various imaging and therapeutic applications, as well as nanotoxicity. In particular, a few emerging strategies that have advanced cancer nanomedicine are also highlighted as the emerging focus such as tumor imprisonment, supramolecular chemotherapy, and DNA nanorobot. The challenge and outlook of some scientific and engineering issues are also discussed in future development. We wish to highlight these new progress of precise nanomedicine with the ultimate goal to inspire more successful explorations of intelligent nanoparticles for future clinical translations. 相似文献
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Nanoparticle electrophoretic translocation through a single nanopore induces a detectable change in the ionic current, which enables the nanopore-based sensing for various bio-analytical applications. In this study, a transient continuum-based model is developed for the first time to investigate the electrokinetic particle translocation through a nanopore by solving the Nernst-Planck equations for the ionic concentrations, the Poisson equation for the electric potential and the Navier-Stokes equations for the flow field using an arbitrary Lagrangian-Eulerian (ALE) method. When the applied electric field is relatively low, a current blockade is expected. In addition, the particle could be trapped at the entrance of the nanopore when the electrical double layer (EDL) adjacent to the charged particle is relatively thick. When the electric field imposed is relatively high, the particle can always pass through the nanopore by electrophoresis. However, a current enhancement is predicted if the EDL of the particle is relatively thick. The obtained numerical results qualitatively agree with the existing experimental results. It is also found that the initial orientation of the particle could significantly affect the particle translocation and the ionic current through a nanopore. Furthermore, a relatively high electric field tends to align the particle with its longest axis parallel to the local electric field. However, the particle's initial lateral offset from the centerline of the nanopore acts as a minor effect. 相似文献
20.
Wilson JT Cui W Kozlovskaya V Kharlampieva E Pan D Qu Z Krishnamurthy VR Mets J Kumar V Wen J Song Y Tsukruk VV Chaikof EL 《Journal of the American Chemical Society》2011,133(18):7054-7064
Layer-by-layer assembly of polyelectrolyte multilayer (PEM) films represents a bottom-up approach for re-engineering the molecular landscape of cell surfaces with spatially continuous and molecularly uniform ultrathin films. However, fabricating PEMs on viable cells has proven challenging owing to the high cytotoxicity of polycations. Here, we report the rational engineering of a new class of PEMs with modular biological functionality and tunable physicochemical properties which have been engineered to abrogate cytotoxicity. Specifically, we have discovered a subset of cationic copolymers that undergoes a conformational change, which mitigates membrane disruption and facilitates the deposition of PEMs on cell surfaces that are tailorable in composition, reactivity, thickness, and mechanical properties. Furthermore, we demonstrate the first successful in vivo application of PEM-engineered cells, which maintained viability and function upon transplantation and were used as carriers for in vivo delivery of PEMs containing biomolecular payloads. This new class of polymeric film and the design strategies developed herein establish an enabling technology for cell transplantation and other therapies based on engineered cells. 相似文献