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.

Patterned self-assembled monolayers formed by microcontact printing direct selective metalization by chemical vapor deposition on planar and nonplanar substrates

Abstract: Self-assembled monolayers (SAMs) of alkylsiloxanes were patterned by microcontact printing (μCP) on a number of substrates : N/Al 2 O 2 , Si/SiO 2 , TiN/TiO 2 , glasses, indium tin oxide (ITO), and plasma-modified polyimide. The patterned SAMs on these surfaces define and direct the selective chemical vapor deposition (CVD) of copper using (hexafluoroacetylacetonato)(vinyltrimethylsilane)copper(I) (Cu I (hfac)(vtms)) as the source gas. This paper presents several examples of microstructures of copper fabricated by selective, SAM-directed CVD, including fabrication of thin-film interconnects (with feature sizes of 0.5-100 μm), and selective filling of trenches and vias (models of microstructures having high aspect ratios) with feature sizes below 1 μm.

Biospecific adsorption of carbonic anhydrase to self-assembled monolayers of alkanethiolates that present benzenesulfonamide groups on gold

Abstract: The biospecific adsorption of proteins at interfaces that present appropriate ligands is important for anchorage-dependent cell culture,1 II,III,screening of combinatorial l1 ibraries,2 biosensors,3 and biocompatible surfaces.4 Fundamental studies of molecular recognition at surfaces by proteins have been limited by a lack of an experimental system having the requisite characteristics:5 (i) a method to prepare surfaces with excellent control—at the molecular scale—over the density and environment of ligands; (ii) an “inert surface” that resists nonspecific adsorption; (iii) a convenient and readily available analytical technique that can measure the adsorption of protein at sub-monolayer coverage in situ and in real time. Here we demonstrate that the combination of (a) mixed self-assembled monolayers (SAMs) of alkanethiolates on gold presenting oligo(ethylene glycol) moieties and ligands and (b) surface plasmon resonance (SPR) spectroscopy meets these requirements. We demonstrate the characteristics of this system using a model system comprising immobilized benzenesulfonamide groups interacting with bovine carbonic anhydrase (EC 4.2.1.1) (Figure 1). We used bovine carbonic anhydrase (CA) in this work because it is a well-characterized monomeric protein (MW = 30 000) that binds para-substituted benzenesulfonamide ligands with equilibrium dissociation constants (Kf) of approximately -6—10-9 M.6 We prepared mixed SAMs comprising different mole fractions ( ) of an alkanethiolate terminated in a benzenesulfonamide ligand (2);7·8 the corresponding ligand 3 binds CA with a value of K¿ of 5 10-8 M in solution.9 The tri(ethylene glycol)-terminated alkanethiol 1 was used as the major

Use of affinity capillary electrophoresis to determine kinetic and equilibrium constants for binding of arylsulfonamides to bovine carbonic anhydrase

Abstract: Affinity capillary electrophoresis (ACE) provides a new approach to studying protein-ligand interactions. The basis for ACE is the change in the electrophoretic mobility of the protein when it forms a complex with its ligand. This binding interaction can be quantified directly for charged ligands or indirectly for neutral ligands in competition with a previously characterized charged ligand. Determination of kinetic and equilibrium constants using ACE relies only on the changes in the migration time and shape (but not the area) of the peak due to protein. Simulation of the protein mobility under conditions of ACE suggests that the experimentally obtained electropherograms can be explained in terms of few variables: on and off rates (and thus, binding constant), concentration of the ligand(s), and relative mobilities of the protein and its complex(es).

Microfluidics Section: Design and Fabrication of Integrated Passive Valves and Pumps for Flexible Polymer 3-Dimensional Microfluidic Systems

Abstract: This paper describes the fabrication of flexible, polymeric 3-dimensional microfluidic systems with integrated check valves (flap and diaphragm valves) and a pump by stacking patterned poly(dimethylsiloxane) (PDMS) layers containing microchannels and vias. We describe this procedure for fabricating, manipulating, and bonding of PDMS membranes and bas-relief plates into multilayer microfluidic devices. The fabrication and demonstration of integrated check valves and a pump in a prototype polymer 3-dimensional microfluidic system is a step toward practical realization of all-polymer, flexible, low-cost, disposable microfluidic devices for biochemical applications.

I and i

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 …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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。

The Theory of Island Biogeography

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

Large-scale pattern growth of graphene films for stretchable transparent electrodes

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.

Fuzzy Nanoassemblies: Toward Layered Polymeric Multicomposites

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.