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George M. Whitesides

Bio: George M. Whitesides is an academic researcher from Harvard University. The author has contributed to research in topics: Microcontact printing & Self-assembled monolayer. The author has an hindex of 240, co-authored 1739 publications receiving 269833 citations. Previous affiliations of George M. Whitesides include University of California, Davis & University of Texas at Austin.


Papers
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Journal ArticleDOI
TL;DR: The ability of a bifunctional polymer to carry out three distinct functions based on polyvalent molecular recognition is demonstrated: recognition of the surface of Gram-positive bacteria, modification of this surface to generate specific binding sites recognized by an antibody, and promotion of phagocytosis of the opsonized bacteria.

54 citations

Journal ArticleDOI
14 Jan 1999-Langmuir
TL;DR: In this paper, a strategy for converting planar patterns into three-dimensional (3D) microstructures with complex topologies is illustrated in the formation of folded tetrahedra, square-based pyramids, cylinders with joints, pop-up cubes, and linked chains and knots.
Abstract: Soft lithography offers a convenient set of methods for the transfer of patterns to planar and nonplanar substrates. Microelectrodeposition can transform thin metal patterns into self-supporting microstructures, weld components together, and strengthen microstructures after deformations. Together, soft lithography and electrochemistry provide synergistic technologies and the basis for a strategy for converting planar patterns into three-dimensional (3D) microstructures with complex topologies. This strategy is illustrated in the formation of folded tetrahedra, square-based pyramids, cylinders with joints, “pop-up” cubes, and linked chains and knots.

54 citations

Journal ArticleDOI
TL;DR: It is demonstrated how the trends in the magnitude of the adhesion forces for chemically heterogeneous systems (solvents and surfaces) measured with CFM can be quantitatively rationalized using the surface tension components approach.
Abstract: We used chemical force microscopy (CFM) to study adhesive forces between surfaces of epoxy resin and self-assembled monolayers (SAMs) capable of hydrogen bonding to different extents. The influence of the liquid medium in which the experiments were carried out was also examined systematically. The molecular character of the tip, polymer, and liquid all influenced the adhesion. Complementary macroscopic contact angle measurements were used to assist in the quantitative interpretation of the CFM data. A direct correlation between surface free energy and adhesion forces was observed in mixed alcohol−water solvents. An increase in surface energy from 2 to 50 mJ/m2 resulted in an increase in adhesion from 4−8 nN to 150−300 nN for tips with radii of 50−150 nm. The interfacial surface energy for identical nonpolar surface groups of SAMs was found not to exceed 2 mJ/m2. An analysis of adhesion data suggests that the solvent was fully excluded from the zone of contact between functional groups on the tip and sampl...

54 citations

01 Dec 1985
TL;DR: In this article, a surface functionalized polyethylene (PE-CO2H) was developed as a substrate with which to study problems in organic surface chemistry, especially wetting, polymer surface reconstruction, and adhesion.
Abstract: : Brief oxidation of low-density polyethylene film with chromic acid in aqueous sulfuric acid introduced carboxylic acid and ketone and/or aldehyde groups onto the surface of the film. The carboxylic acid moieties can be used to attach more complex functionality to the polymer surface. We are developing this surface-functionalized polyethylene (named 'polyethylene carboxylic acid,' PE-CO2H, to emphasize the functional group that dominates its surface properties) as a substrate with which to study problems in organic surface chemistry--especially wetting, polymer surface reconstruction, and adhesion--using physical-organic techniques. This document describes the preparation, characterization, and fluorescence properties of derivatives of PE-CO2H in which the Dansyl (5-dimethylaminonaphthalene-1-sulfonyl) group has been covalently attached by amide links to the surface carbonyl moieties. Keywords: Acidity; and Solvent effects.

54 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols used xiii 1.
Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

14,171 citations

Journal ArticleDOI
05 Feb 2009-Nature
TL;DR: The direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers is reported, and two different methods of patterning the films and transferring them to arbitrary substrates are presented, implying that the quality of graphene grown by chemical vapours is as high as mechanically cleaved graphene.
Abstract: Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of approximately 280 Omega per square, with approximately 80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm(2) V(-1) s(-1) and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.

10,033 citations

Journal ArticleDOI
29 Aug 1997-Science
TL;DR: In this article, a general approach for multilayers by consecutive adsorption of polyanions and polycations has been proposed and has been extended to other materials such as proteins or colloids.
Abstract: Multilayer films of organic compounds on solid surfaces have been studied for more than 60 years because they allow fabrication of multicomposite molecular assemblies of tailored architecture. However, both the Langmuir-Blodgett technique and chemisorption from solution can be used only with certain classes of molecules. An alternative approach—fabrication of multilayers by consecutive adsorption of polyanions and polycations—is far more general and has been extended to other materials such as proteins or colloids. Because polymers are typically flexible molecules, the resulting superlattice architectures are somewhat fuzzy structures, but the absence of crystallinity in these films is expected to be beneficial for many potential applications.

9,593 citations