151
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Kang HJ, Noh TH, Jin JS, Jung OS. Cyclodimers versus Cyclotrimers via Solvent or Temperature Effects on Metallacyclization. Inorg Chem 2008; 47:5528-30. [DOI: 10.1021/ic800436n] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hyun Ji Kang
- Department of Chemistry, Pusan National University, Pusan 609-735, Korea, and Pusan Center, Korea Basic Science and Institute, Pusan 609-735, Korea
| | - Tae Hwan Noh
- Department of Chemistry, Pusan National University, Pusan 609-735, Korea, and Pusan Center, Korea Basic Science and Institute, Pusan 609-735, Korea
| | - Jong Sung Jin
- Department of Chemistry, Pusan National University, Pusan 609-735, Korea, and Pusan Center, Korea Basic Science and Institute, Pusan 609-735, Korea
| | - Ok-Sang Jung
- Department of Chemistry, Pusan National University, Pusan 609-735, Korea, and Pusan Center, Korea Basic Science and Institute, Pusan 609-735, Korea
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152
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Chen LY, Zhang YG, Wang WZ, Zhang ZD. Tunable Synthesis of Various Hierarchical Structures of In(OH)3 and In2O3 Assembled by Nanocubes. Eur J Inorg Chem 2008. [DOI: 10.1002/ejic.200700936] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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153
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Ariga K, Hill JP, Lee MV, Vinu A, Charvet R, Acharya S. Challenges and breakthroughs in recent research on self-assembly. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2008; 9:014109. [PMID: 27877935 PMCID: PMC5099804 DOI: 10.1088/1468-6996/9/1/014109] [Citation(s) in RCA: 389] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 05/13/2008] [Accepted: 02/22/2008] [Indexed: 05/18/2023]
Abstract
The controlled fabrication of nanometer-scale objects is without doubt one of the central issues in current science and technology. However, existing fabrication techniques suffer from several disadvantages including size-restrictions and a general paucity of applicable materials. Because of this, the development of alternative approaches based on supramolecular self-assembly processes is anticipated as a breakthrough methodology. This review article aims to comprehensively summarize the salient aspects of self-assembly through the introduction of the recent challenges and breakthroughs in three categories: (i) types of self-assembly in bulk media; (ii) types of components for self-assembly in bulk media; and (iii) self-assembly at interfaces.
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Affiliation(s)
- Katsuhiko Ariga
- World Premier International (WPI), Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Jonathan P Hill
- World Premier International (WPI), Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
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154
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Tolley MT, Baisch A, Krishnan M, Erickson D, Lipson H. Interfacing methods for fluidically-assembled microcomponents. ACTA ACUST UNITED AC 2008. [DOI: 10.1109/memsys.2008.4443845] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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155
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Leong TG, Lester PA, Koh TL, Call EK, Gracias DH. Surface tension-driven self-folding polyhedra. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:8747-51. [PMID: 17608507 DOI: 10.1021/la700913m] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We discuss finite element simulations and experiments involving the surface tension-driven self-folding of patterned polyhedra. Two-dimensional (2D) photolithographically patterned templates folded spontaneously when solder hinges between adjacent faces were liquefied. Minimization of interfacial free energy of the molten solder with the surrounding fluidic medium caused the solder to ball up, resulting in a torque that rotated adjacent faces and drove folding. The simulations indicate that the folding process can be precisely controlled, has fault tolerance, and can be used to fold polyhedra composed of a variety of materials, ranging in size from the millimeter scale down to the nanometer scale. Experimentally, we have folded metallic, arbitrarily patterned polyhedra ranging in size from 2 mm to 15 microm.
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Affiliation(s)
- Timothy G Leong
- Department of Chemical and Biomolecular Engineering and Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA
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156
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Onoe H, Matsumoto K, Shimoyama I. Three-dimensional sequential self-assembly of microscale objects. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2007; 3:1383-9. [PMID: 17594683 DOI: 10.1002/smll.200600721] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Affiliation(s)
- Hiroaki Onoe
- Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan. )
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157
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Glotzer SC, Solomon MJ. Anisotropy of building blocks and their assembly into complex structures. NATURE MATERIALS 2007; 6:557-62. [PMID: 17667968 DOI: 10.1038/nmat1949] [Citation(s) in RCA: 1804] [Impact Index Per Article: 106.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Accepted: 05/10/2007] [Indexed: 05/16/2023]
Abstract
A revolution in novel nanoparticles and colloidal building blocks has been enabled by recent breakthroughs in particle synthesis. These new particles are poised to become the 'atoms' and 'molecules' of tomorrow's materials if they can be successfully assembled into useful structures. Here, we discuss the recent progress made in the synthesis of nanocrystals and colloidal particles and draw analogies between these new particulate building blocks and better-studied molecules and supramolecular objects. We argue for a conceptual framework for these new building blocks based on anisotropy attributes and discuss the prognosis for future progress in exploiting anisotropy for materials design and assembly.
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Affiliation(s)
- Sharon C Glotzer
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, USA.
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158
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Chun IS, Kwon JA, Yoon HJ, Bae MN, Hong J, Jung OS. Interactions of Microcrystals through Free Pyridyl Groups: Microcross and Chain-Arrayed Supercrystals of a Palladium(II) Complex. Angew Chem Int Ed Engl 2007; 46:4960-3. [PMID: 17508387 DOI: 10.1002/anie.200701152] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- In Sung Chun
- Department of Chemistry, Pusan National University, 30 Jangjeon, Pusan 609-735, Korea
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159
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Chun I, Kwon J, Yoon H, Bae M, Hong J, Jung OS. Interactions of Microcrystals through Free Pyridyl Groups: Microcross and Chain-Arrayed Supercrystals of a Palladium(II) Complex. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200701152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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160
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Sharma R. Thermally controlled fluidic self-assembly. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:6843-9. [PMID: 17497901 DOI: 10.1021/la063516q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A novel approach for the fluidic self-assembly (FSA) of microparts in a multibatch process utilizing the thermal behavior of the carrier fluid as a means for selecting binding sites is presented. In the system studied, fluidic assembly takes place due to a capillary bridge between hexadecane deposited on a hydrophobic patch on a substrate and a hydrophobic surface on a micropart suspended in a carrier fluid. When desired, FSA of microparts is prevented by causing the surrounding carrier fluid to form a gel when heated, offering a method for directing self-assembly to sites that are not heated. It is shown that a suitable carrier fluid is 15 wt % Pluronic F127, which gels at about 40 degrees C when tested in the geometry used to demonstrate the concept. Experimental results demonstrating FSA and thermally controlled fluidic assembly (TCFSA) of plastic microparts dispersed in Pluronic F127 solution are presented. Potentially, TCFSA offers a general method for directed assembly as it relies on restricting the transport of microparts to a site rather than interfering with the fundamental attractive forces responsible for self-assembly.
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Affiliation(s)
- Ravi Sharma
- Research and Development Laboratories, Eastman Kodak Company, Rochester, New York 14650, USA.
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161
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“Bottom-up” approach for implementing nano/microstructure using biological and chemical interactions. BIOTECHNOL BIOPROC E 2007. [DOI: 10.1007/bf02931092] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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162
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Ankamwar B, Chaudhary M, Sastry M. Gold Nanotriangles Biologically Synthesized using Tamarind Leaf Extract and Potential Application in Vapor Sensing. ACTA ACUST UNITED AC 2007. [DOI: 10.1081/sim-200047527] [Citation(s) in RCA: 366] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | - Minakshi Chaudhary
- b Nanoscience Group, Materials Chemistry Division , National Chemical Laboratory , Pune, India
| | - Murali Sastry
- b Nanoscience Group, Materials Chemistry Division , National Chemical Laboratory , Pune, India
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163
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Zhang J, Wei S, Lin J, Luo J, Liu S, Song H, Elawad E, Ding X, Gao J, Qi S, Tang C. Template-Free Preparation of Bunches of Aligned Boehmite Nanowires. J Phys Chem B 2006; 110:21680-3. [PMID: 17064125 DOI: 10.1021/jp064725m] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A simple method based on a hydrothermal process using alkali salts as mineralizers is proposed for the synthesis of aligned bunches of boehmite (gamma-AlOOH) nanowires without a template's assistance. Most bunches of aligned boehmite nanowires are constructed by two separated shorter bundles with widths of 700 to approximately 800 nm and lengths of about 1 microm. XRD patterns, FTIR spectra, and SEM and TEM images were used to characterize the products. The specific surface area and pore-size distribution of the obtained product as determined by gas-sorption measurements show that the boehmite bundles possess a high BET surface area and porosity properties. The importance of adding Na2B4O7 salts for the formation of bundle morphologies has been discussed.
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Affiliation(s)
- Jun Zhang
- College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China
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164
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Zhou CH, Tong DS, Bao M, Du ZX, Ge ZH, Li XN. Generation and characterization of catalytic nanocomposite materials of highly isolated iron nanoparticles dispersed in clays. Top Catal 2006. [DOI: 10.1007/s11244-006-0059-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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165
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Stauth SA, Parviz BA. Self-assembled single-crystal silicon circuits on plastic. Proc Natl Acad Sci U S A 2006; 103:13922-7. [PMID: 16968780 PMCID: PMC1599889 DOI: 10.1073/pnas.0602893103] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We demonstrate the use of self-assembly for the integration of freestanding micrometer-scale components, including single-crystal, silicon field-effect transistors (FETs) and diffusion resistors, onto flexible plastic substrates. Preferential self-assembly of multiple microcomponent types onto a common platform is achieved through complementary shape recognition and aided by capillary, fluidic, and gravitational forces. We outline a microfabrication process that yields single-crystal, silicon FETs in a freestanding, powder-like collection for use with self-assembly. Demonstrations of self-assembled FETs on plastic include logic inverters and measured electron mobility of 592 cm2/V-s. Finally, we extend the self-assembly process to substrates each containing 10,000 binding sites and realize 97% self-assembly yield within 25 min for 100-microm-sized elements. High-yield self-assembly of micrometer-scale functional devices as outlined here provides a powerful approach for production of macroelectronic systems.
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Affiliation(s)
- Sean A. Stauth
- Department of Electrical Engineering, The Paul G. Allen Center for Computer Science and Engineering, University of Washington, Room AE100R, Campus Box 352500, Seattle, WA 98195-2500
| | - Babak A. Parviz
- Department of Electrical Engineering, The Paul G. Allen Center for Computer Science and Engineering, University of Washington, Room AE100R, Campus Box 352500, Seattle, WA 98195-2500
- *To whom correspondence should be addressed. E-mail:
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166
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Hicks SD, Henley CL. Irreversible growth model for virus capsid assembly. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:031912. [PMID: 17025672 DOI: 10.1103/physreve.74.031912] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Revised: 08/08/2006] [Indexed: 05/08/2023]
Abstract
We model the spontaneous assembly of a capsid (a virus' closed outer shell) from many copies of identical units, using entirely irreversible steps and only information local to the growing edge. Our model is formulated in terms of (i) an elastic Hamiltonian with stretching and bending stiffness and a spontaneous curvature, and (ii) a set of rate constants for the addition of new units or bonds. An ensemble of highly irregular capsids is generated, unlike the well-known icosahedrally symmetric viruses, but (we argue) plausible as a way to model the irregular capsids of retroviruses such as HIV. We found that (i) the probability of successful capsid completion decays exponentially with capsid size; (ii) capsid size depends strongly on spontaneous curvature and weakly on the ratio of the bending and stretching elastic stiffnesses of the shell; (iii) the degree of localization of Gaussian curvature (a measure of facetedness) depends heavily on the ratio of elastic stiffnesses.
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Affiliation(s)
- Stephen D Hicks
- Department of Physics, Cornell University, Ithaca, New York 14853, USA.
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167
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Zhang J, Liu S, Lin J, Song H, Luo J, Elssfah EM, Ammar E, Huang Y, Ding X, Gao J, Qi S, Tang C. Self-Assembly of Flowerlike AlOOH (Boehmite) 3D Nanoarchitectures. J Phys Chem B 2006; 110:14249-52. [PMID: 16854128 DOI: 10.1021/jp062105f] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, a hydrothermal route using an ethanol-water solution to progressively synthesize a sequence of flowerlike three-dimensional gamma-AlOOH boehmite nanostructures without employing templates or matrixes for self-assembly is presented. The flowerlike boehmite nanoarchitectures exhibit three hierarchies of self-organization, i.e., single-crystalline nanorods, nanostrips, and bundles, which are characterized by scanning and transmission electron microscopy. The sequence of products obtained after different processing times indicates a self-assembly mechanism. The hydrogen bonding on the surface of nanorods or nanostrips possibly plays a key role, as identified by FTIR spectra of the products after they had been heated to 1000 degrees C. The specific surface area and pore-size distribution of the obtained product as determined by gas-sorption measurements show that the boehmite nanoarchitectures exhibit high BET surface area and porosity properties.
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Affiliation(s)
- Jun Zhang
- Department of Physics, Central China Normal University, Wuhan 430079, P.R. China
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168
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Steinbacher JL, Moy RWY, Price KE, Cummings MA, Roychowdhury C, Buffy JJ, Olbricht WL, Haaf M, McQuade DT. Rapid Self-Assembly of Core−Shell Organosilicon Microcapsules within a Microfluidic Device. J Am Chem Soc 2006; 128:9442-7. [PMID: 16848481 DOI: 10.1021/ja0612403] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The preparation of hierarchically structured organosilicon microcapsules from commercially available starting materials is described. Using a microfluidic device, an emulsion of dichlorodiphenylsilane is formed in a continuous phase of aqueous glycerol. The silane droplets undergo hydrolysis, condensation, and crystallization within minutes to form self-assembled, core-shell microcapsules. The microparticles have been characterized with light and electron microscopy, nuclear magnetic resonance spectroscopy (NMR), diffusion-ordered NMR spectroscopy (DOSY), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffraction (XRD). The characterization data show that the microcapsule walls consist of amorphous, oligomeric poly(diphenylsiloxane) surrounded by a spiny layer of crystalline diphenylsilanediol. Glycerol is occluded within the wall material but is not covalently bound to the silicon components. Glycerol is a crucial element for producing low-dispersity microcapsules with well-ordered surface spines, as the use of methyl cellulose as viscomodifier yields amorphous surfaces.
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Affiliation(s)
- Jeremy L Steinbacher
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA
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169
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Fialkowski M, Bishop KJM, Klajn R, Smoukov SK, Campbell CJ, Grzybowski BA. Principles and Implementations of Dissipative (Dynamic) Self-Assembly. J Phys Chem B 2006; 110:2482-96. [PMID: 16471845 DOI: 10.1021/jp054153q] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dynamic self-assembly (DySA) processes occurring outside of thermodynamic equilibrium underlie many forms of adaptive and intelligent behaviors in natural systems. Relatively little, however, is known about the principles that govern DySA and the ways in which it can be extended to artificial ensembles. This article discusses recent advances in both the theory and the practice of nonequilibrium self-assembly. It is argued that a union of ideas from thermodynamics and dynamic systems' theory can provide a general description of DySA. In parallel, heuristic design rules can be used to construct DySA systems of increasing complexities based on a variety of suitable interactions/potentials on length scales from nanoscopic to macroscopic. Applications of these rules to magnetohydrodynamic DySA are also discussed.
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Affiliation(s)
- Marcin Fialkowski
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA
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170
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Gu Z, Ye H, Smirnova D, Small D, Gracias DH. Reflow and electrical characteristics of nanoscale solder. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2006; 2:225-9. [PMID: 17193025 DOI: 10.1002/smll.200500296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- Zhiyong Gu
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
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171
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Liu Y, Chu Y, Li M, Li L, Dong L. In situ synthesis and assembly of copper oxide nanocrystals on copper foil via a mild hydrothermal process. ACTA ACUST UNITED AC 2006. [DOI: 10.1039/b512481f] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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172
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173
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Maksimuk S, Teng X, Yang H. Planar tripods of platinum: formation and self-assembly. Phys Chem Chem Phys 2006; 8:4660-3. [PMID: 17047763 DOI: 10.1039/b611186f] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This communication describes a synthesis of planar tripods of platinum and their assembly into two-dimensional (2D) nano-structures using the Langmuir-Blodgett (LB) technique.
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Affiliation(s)
- Sean Maksimuk
- Department of Chemical Engineering, University of Rochester, Rochester, NY 14627, USA
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174
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Onoe H, Gel M, Hoshino K, Matsumoto K, Shimoyama I. Direct measurement of the binding force between microfabricated particles and a planar surface in aqueous solution by force-sensing piezoresistive cantilevers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:11251-61. [PMID: 16285798 DOI: 10.1021/la051666f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We propose a force measurement method for evaluating the binding force between microscale flat surfaces in an aqueous solution. Using force-sensing piezoresistive cantilevers with sub-nanonewton force resolution, we have directly measured binding forces between SiO2-SiO2 microcontacts, which were created by gravity-driven random collision between microfabricated SiO2 cylindrical particles and a planar SiO2 substrate in a HCl solution. First, to examine our method we measured the pH dependence of the binding force. The binding forces were 12 and 5.8 nN at pH 1.0 and 2.0, respectively. As the pH increased, the binding force decreased and became zero at pH greater than 3.0. We confirmed that the bindings were based on the van der Waals' (VDW) force at pH 2.0 or less whereas a repulsive double-layer force acted between the surfaces at pH 3.0 or more. Second, the binding forces were categorized into a friction force or an adhesion force between the particles and the substrate. In the measurement, the friction force between the particle and the substrate was measured in the case when the particle slid on the substrate. On the contrary, the adhesion force was measured when the particle came off the substrate. Whether the particle slid or came off depended on the aspect ratio of the particle. We fabricated cylindrical particles with an aspect ratio of 0.03-2.0 and distinguished the friction force from the adhesion force by changing the aspect ratio of the particles. As a result, the friction force per unit contact area between SiO2-SiO2 flat surfaces was found to be 330 pN/microm2 +/- 20% when we used particles with a low aspect ratio (<0.1), and the adhesion force per unit contact area was 90 pN/microm2 +/- 20% for particles with a high aspect ratio (>0.4). For fluidic self-assembly that utilizes microscale surface contact in a liquid, our measurement method is an effective tool for studying and developing systems.
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Affiliation(s)
- Hiroaki Onoe
- Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo
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175
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Basch H, Cohen R, Ratner MA. Interface geometry and molecular junction conductance: geometric fluctuation and stochastic switching. NANO LETTERS 2005; 5:1668-75. [PMID: 16159203 DOI: 10.1021/nl050702s] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Metal/molecule/metal transport junctions can transport charge in the elastic scattering (Landauer) regime if the injection gap is large and the molecule is relatively short. Stochastic switching and broad conduction peak distributions have been observed in such junctions. We examine the effect of altering interface geometry on transport, using density functional calculations. For most structures, variations in conductance of order 0-300% are found, but when an atomic wire of Au binds to the molecule, symmetry changes can modify currents by a factor of 10(3).
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Affiliation(s)
- H Basch
- Department of Chemistry, Bar-Ilan University, Ramat Gan, Israel
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176
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Abstract
4-mercaptoaniline functionalised platinum particles of 2 nm diameter were synthesised and over-grafted with 2-thiophenecarbonyl chloride. The derivative particles were dispersed in DMSO and gave long term stable suspensions. The Langmuir-Blodgett technique was then used to build up stable Langmuir-Blodgett films and the electrochemical behaviour of these ultra-thin films towards oxygen reduction was investigated in an acidic medium. It revealed direct activity without any previous activation treatments despite of the presence of the organic shell at the particle surface. Furthermore, XPS experiments revealed that the organic crown was not significantly destroyed on prolonged cycling. The results open a way to study original and versatile platinum-based nanocomposites.
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177
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Abstract
A novel self-assembled microstructure, nestlike Mg(5)(CO(3))(4)(OH)(2).4H(2)O spheres, is formed by a self-assembly of nanosheets in the hydrothermal process. MgO with the similar morphology can be obtained by calcination of nestlike Mg(5)(CO(3))(4)(OH)(2).4H(2)O. MgO precursors with a uniform, ellipsoid-shaped, and smooth surface or flowerlike architecture, built by individual thin sheets, can be well-obtained by carefully controlling pH values of the initial reaction solution. The nestlike MgO exhibits a unique geometrical shape; its surface is composed of uniform MgO nanosheets. The unique MgO microstructure with high surface areas may possess promising applications as the sorbent for chemisorption and destructive adsorption of various pollutants.
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Affiliation(s)
- Chenglin Yan
- State Key Laboratory of Fine Chemicals and School of Chemical Engineering, Dalian University of Technology, 158 Zhongshan Road, Dalian 116012, China
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178
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Guldi DM, Gouloumis A, Vázquez P, Torres T, Georgakilas V, Prato M. Nanoscale Organization of a Phthalocyanine−Fullerene System: Remarkable Stabilization of Charges in Photoactive 1-D Nanotubules. J Am Chem Soc 2005; 127:5811-3. [PMID: 15839678 DOI: 10.1021/ja043283u] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Induction of self-organization between zinc phthalocyanine (ZnPc) and C60 moieties in a novel amphiphilic ZnPc-C60 salt results in uniformly nanostructured 1-D nanotubules. Their photoreactivity, in terms of ultrafast charge separation (i.e., approximately 1012 s-1) and ultraslow charge recombination (i.e., approximately 103 s-1), is remarkable. In addition, the observed ZnPc*+-C60*- lifetime of 1.4 ms implies, relative to that of the monomeric ZnPc-C60 ( approximately 3 ns), an impressive stabilization of 6 orders of magnitude.
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Affiliation(s)
- Dirk M Guldi
- Universität Erlangen, Institute for Physical and Theoretical Chemistry, 91058 Erlangen, Germany.
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179
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de Cuendias A, Backov R, Cloutet E, Cramail H. Synthesis of gold nanoparticles coated onto polyurethane microspheres. ACTA ACUST UNITED AC 2005. [DOI: 10.1039/b510556k] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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180
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Gu Z, Chen Y, Gracias DH. Surface tension driven self-assembly of bundles and networks of 200 nm diameter rods using a polymerizable adhesive. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:11308-11311. [PMID: 15595750 DOI: 10.1021/la047937o] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This letter demonstrates the first utilization of surface tension based self-assembly on the 200 nm scale to form mechanically stable aggregates comprised of metallic rods. The self-assembly occurs as a result of the minimization of interfacial tension of liquid layers of a hydrophobic polymerizable adhesive that is precipitated on the rods. After the assembly, the adhesive is polymerized to form permanently bonded aggregates. Depending on the patterning of the rods and the chemical functionalization used, either closed 3D bundles or open 2D networks can be formed.
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Affiliation(s)
- Zhiyong Gu
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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181
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Fu L, Cao L, Liu Y, Zhu D. Molecular and nanoscale materials and devices in electronics. Adv Colloid Interface Sci 2004; 111:133-57. [PMID: 15589806 DOI: 10.1016/j.cis.2004.09.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Over the past several years, there have been many significant advances toward the realization of electronic computers integrated on the molecular scale and a much greater understanding of the types of materials that will be useful in molecular devices and their properties. It was demonstrated that individual molecules could serve as incomprehensibly tiny switch and wire one million times smaller than those on conventional silicon microchip. This has resulted very recently in the assembly and demonstration of tiny computer logic circuits built from such molecular scale devices. The purpose of this review is to provide a general introduction to molecular and nanoscale materials and devices in electronics.
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Affiliation(s)
- Lei Fu
- Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, PR China
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182
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Schalley CA. Elements for the construction of molecular devices: template effects and self‐assembly. J PHYS ORG CHEM 2004. [DOI: 10.1002/poc.826] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Christoph A. Schalley
- Kekulé‐Institut für Organische Chemie und Biochemie der Universität, Gerhard‐Domagk‐Strasse 1, D‐53121 Bonn, Germany
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183
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Zhang F, Chen J, Zhang X, Gao W, Jin R, Guan N. Simple and low-cost preparation method for highly dispersed Pd/TiO2 catalysts. Catal Today 2004. [DOI: 10.1016/j.cattod.2004.06.023] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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184
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Zheng W, Buhlmann P, Jacobs HO. Sequential shape-and-solder-directed self-assembly of functional microsystems. Proc Natl Acad Sci U S A 2004; 101:12814-7. [PMID: 15317938 PMCID: PMC516478 DOI: 10.1073/pnas.0404437101] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We demonstrate the fabrication of packaged microsystems that contain active semiconductor devices and passive components by using a directed self-assembly technique. The directed self-assembly is accomplished by combining geometrical shape recognition with site-specific binding involving liquid solder. Microfabricated components with matching complementary shapes, circuits, and liquid solder-coated areas were suspended in ethylene glycol and agitated by using a turbulent liquid flow to initiate the self-assembly. Microsystems were obtained by sequentially adding components of different types. Six hundred AlGaInP/GaAs light-emitting diode segments with a chip size of 200 microm were assembled onto device carriers with a yield of 100% in 2 min. Packaged light-emitting diodes formed with yields exceeding 97% as a result of two self-assembly steps in 4 min. This self-assembly procedure, based on geometrical shape recognition and subsequent binding to form mechanical and electrical connections, provides a high distinguishing power between different components and a route to nonrobotic parallel assembly of electrically functional hybrid microsystems in three dimensions.
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Affiliation(s)
- Wei Zheng
- Departments of Electrical and Computer Engineering and Chemistry, University of Minnesota, 200 Union Street SE, Minneapolis, MN 55455, USA
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185
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Osterloh F, Hiramatsu H, Porter R, Guo T. Alkanethiol-induced structural rearrangements in silica-gold core-shell-type nanoparticle clusters: an opportunity for chemical sensor engineering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:5553-8. [PMID: 15986699 DOI: 10.1021/la0348719] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Electrostatically bonded SiO2.Au nanoparticle clusters form by reaction of 3-aminopropylsilane-modified SiO2 spheres (470 nm) with citrate-coated gold nanoparticles (9.7 nm) in water. Reaction of the clusters with 0.01 M KBr or HCl solution induces desorption of the gold nanoparticles within minutes. Reaction of the clusters with alkanethiols CnH2n+1SH (n = 2-18) at 80 degrees C causes the gold nanoparticles to form stringlike gold nanoparticle structures for thiols with short alkane groups (n = 2, 3, 4) and hexagonally packed arrays of gold nanoparticles for thiols with long alkane groups (n = 5-18) on the silica surfaces. The structural changes indicate that the bonding between Au and SiO2 nanoparticles has changed from electrostatic to van der Waals. Elemental analyses show that the reaction with hexanethiol does not affect the Au/Si/O composition of the SiO2.Au cluster, and Raman spectra on the hexanethiol-reacted cluster indicate the formation of a thiol SAM on the gold nanoparticles. The thiol-reacted SiO2.Au clusters display characteristic shifts of the absorption maxima in the visible spectra, and there is an inverse relation between these shifts and the lengths of the alkyl groups in the thiols. This relationship can be understood in terms of the free electron model for metals. The use of SiO2.Au nanoparticle clusters as coulometric sensors for the qualitative detection of thiols is discussed.
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Affiliation(s)
- Frank Osterloh
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, USA.
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186
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Liu B, Zeng HC. Mesoscale Organization of CuO Nanoribbons: Formation of “Dandelions”. J Am Chem Soc 2004; 126:8124-5. [PMID: 15225047 DOI: 10.1021/ja048195o] [Citation(s) in RCA: 375] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A two-tiered organizing scheme with multiple-length scales for construction of dandelion-like hollow CuO microspheres has been elucidated: (1) mesoscale formation of rhombic building units from smaller nanoribbons via oriented aggregation and (2) macroscopic organization of these units into the CuO microspheres. This self-assembly concept may also be applicable to other metal oxides by creating geometric constraints for constructional units.
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Affiliation(s)
- Bin Liu
- Department of Chemical and Biomolecular Engineering, Faculty of Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
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187
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Gothelf KV, Thomsen A, Nielsen M, Cló E, Brown RS. Modular DNA-programmed assembly of linear and branched conjugated nanostructures. J Am Chem Soc 2004; 126:1044-6. [PMID: 14746471 DOI: 10.1021/ja038333u] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new strategy for self-assembly and covalent coupling of encoded molecular modules into nanostructures with predetermined connectivity has been developed. The method uses DNA-functionalized oligo(phenylene ethynylene)-derived organic modules for controlling the assembly and covalent coupling of multiple modules. Rigid linear modules (LM) and tripoidal modules (TM) were functionalized with short oligonucleotides at each terminus. They can hybridize and thereby link up modules containing complementary sequences. Each terminus of the oligo(phenylene ethynylene) modules also consists of a salicylaldehyde moiety, which can form metal-salen complexes with other modules. The salicylaldehyde groups of two modules are brought in proximity when their adjoining DNA sequences are complementary, and they selectively form a manganese-salen complex in the presence of ethylenediamine and manganese acetate. The resulting structures consist of a matrix of linear and branched oligo(phenylene ethynylene)s which are linked by conjugated and rigid manganese-salen complexes. These nanostructures are potential conductors for applications in molecular electronics.
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Affiliation(s)
- Kurt V Gothelf
- Center for Catalysis and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Langelandsgade 140, Aarhus University, 8000 Aarhus C, Denmark.
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188
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189
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190
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de la Escosura A, Martínez-Díaz MV, Thordarson P, Rowan AE, Nolte RJM, Torres T. Donor−Acceptor Phthalocyanine Nanoaggregates. J Am Chem Soc 2003; 125:12300-8. [PMID: 14519015 DOI: 10.1021/ja030038m] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel donor-acceptor bisphthalocyanine (bis-Pc, 1) in which two different Pc units (Zn(II)-Pc and Ni(II)-Pc) are linked via vinylene spacers to the pseudopara positions of a central [2.2]paracyclophane moiety is described. The synthesis of 1 is achieved by two successive Heck reactions of pseudopara-divinyl[2.2]paracyclophane 9 with, sequentially, a zinc(II)- and a nickel(II)-iodophthalocyanine (4 and 5, respectively). The self-assembly ability of 1, which is the result of the complementary donor-acceptor character of its phthalocyanine units, has been assessed by a variety of techniques. It is revealed that 1 forms one-dimensional aggregates of nanometer-sized dimension, whereas equimolar mixtures of the donor and acceptor Pc subunits 2 and 3, although strongly interacting, do not give large arrays. The aggregates of 1 represent a novel type of supramolecular polymers based mainly upon donor-acceptor interactions.
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Affiliation(s)
- Andrés de la Escosura
- Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain
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191
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McCreery R, Dieringer J, Solak AO, Snyder B, Nowak AM, McGovern WR, DuVall S. Molecular rectification and conductance switching in carbon-based molecular junctions by structural rearrangement accompanying electron injection. J Am Chem Soc 2003; 125:10748-58. [PMID: 12940761 DOI: 10.1021/ja0362196] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular junctions were fabricated consisting of a 3.7 nm thick layer of nitroazobenzene (NAB) molecules between a pyrolyzed photoresist substrate (PPF) and a titanium top contact which was protected from oxidation by a layer of gold. Raman spectroscopy, XPS, and AFM revealed that the NAB layer was 2-3 molecules thick and was bonded to the two conducting contacts by C-C and N-Ti covalent bonds. The current/voltage behavior of the PPF/NAB(3.7)/Ti junctions showed strong and reproducible rectification, with the current at +2 V exceeding that at -2 V by a factor of 600. The observed current density at +3 V was 0.71 A/cm(2), or about 10(5) e(-)/s/molecule. The i/V response was strongly dependent on temperature and scan rate, with the rectification ratio decreasing for lower temperature and faster scans. Junction conductivity increased with time over several seconds at room temperature in response to positive voltage pulses, with the rate of increase larger for more positive potentials. Voltage pulses to positive potentials and back to zero volts revealed that electrons are injected from the Ti to the NAB, to the extent of about 0.1-1 e(-)/molecule for a +3 V pulse. These electrons cause an activated transition of the NAB into a more conductive quinoid state, which in turn causes an increase in conductivity. The transition to the quinoid state involves nuclear rearrangement which occurs on a submillisecond to several second time scale, depending on the voltage applied. The quinoid state is stable as long as the applied electric field is present, but reverts back to NAB within several minutes after the field is relaxed. The results are interpreted in terms of a thermally activated, potential dependent electron transfer into the 3.7 nm NAB layer, which brings about a conductivity increase of several orders of magnitude.
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Affiliation(s)
- Richard McCreery
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA.
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192
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Zhi ZL, Murakami Y, Morita Y, Hasan Q, Tamiya E. Multianalyte immunoassay with self-assembled addressable microparticle array on a chip. Anal Biochem 2003; 318:236-43. [PMID: 12814627 DOI: 10.1016/s0003-2697(03)00117-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper describes the random fluidic self-assembly of metallic particles into addressable two-dimensional microarrays and the use of these arrays as a platform for constructing a biochip useful for bioassays. The basic units in the assembly were the microfabricated particles carrying a straightforward visible code and the corresponding array template patterned on a glass substrate. The particles consisted of a hydrophobic and magnetic Ni-polytetrafluoroethylene (PTFE) composite layer on one face, and on the other face a gold layer that was modified for biomolecular attachment. An array template was photoresist-patterned with spatially discrete microwells in which an electrodeposited Ni-PTFE hydrophobic composite layer and a hydrophobic photo-adhesive coating were deposited. The particles, after biomaterial attachment and binding processes in bulk, were self-assembled randomly onto the lubricated bonding sites on the chip substrate, driven by a combination of magnetic, hydrophobic, and capillary interactions. The encoding symbol carried by the particles was used as the signature for the identification of each target/assay attached to the particle surface. We demonstrate here the utility of microfabricated-encoded particle arrays for conducting multianalyte immunoassays in a parallel fashion with the use of imaging detection.
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Affiliation(s)
- Zheng-liang Zhi
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan
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193
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Ng JMK, Fuerstman MJ, Grzybowski BA, Stone HA, Whitesides GM. Self-assembly of gears at a fluid/air interface. J Am Chem Soc 2003; 125:7948-58. [PMID: 12823016 DOI: 10.1021/ja0347235] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper describes a dynamic system-a system that develops order only when dissipating energy-comprising millimeter to centimeter scale gears that self-assemble into a simple machine at a fluid/air interface. The gears are driven externally and indirectly by magnetic interactions; they are made of poly(dimethylsiloxane) (PDMS) or magnetically doped PDMS, and fabricated by soft lithography. Transfer of torque between gears can take place through three different mechanisms: mechanical interaction, hydrodynamic shear, and capillarity/overlap of menisci. Interplay between these forces allows interactions and motions that are not possible with conventional systems of gears.
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Affiliation(s)
- Jessamine M K Ng
- Division of Engineering and Applied Sciences, Pierce Hall, Harvard University, Cambridge, MA 02138, USA
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194
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195
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Wu H, Thalladi VR, Whitesides S, Whitesides GM. Using hierarchical self-assembly to form three-dimensional lattices of spheres. J Am Chem Soc 2002; 124:14495-502. [PMID: 12452727 DOI: 10.1021/ja0210446] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper describes an approach to the fabrication of three-dimensional (3-D) structures of millimeter-scale spherical beads having a range of lattices-tetragonal, cubic, and hexagonal-using hierarchical self-assembly. The process has five steps: (i) metal-coated beads are packed in a rod-shaped cavity in an elastomeric polymer (poly(dimethylsiloxane), PDMS); (ii) the beads are embedded in a second polymer (PDMS or polyurethane, PU) using a procedure that leaves the parts of the beads in contact with the PDMS exposed; (iii) the exposed areas of the beads are coated with a solder having a low melting point; (iv) the polymer rods-with embedded beads and exposed solder drops-are suspended in an approximately isodense medium (an aqueous solution of KBr) and allowed to self-assemble by capillary interactions between the drops of molten solder; and (v) the assembly is finished by several procedures, including removing the beads from the polymer matrix by dissolution, filling the voids left with another material, and dissolving the matrix. The confinement of the beads in regular structures in polymer rods makes it possible to generate self-assembled structures with a variety of 3-D lattices; the type of the lattice formed can be controlled by varying the size of the beads, and the size and shape of the cross-section of the rods.
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Affiliation(s)
- Hongkai Wu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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196
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Skaff H, Ilker MF, Coughlin EB, Emrick T. Preparation of cadmium selenide-polyolefin composites from functional phosphine oxides and ruthenium-based metathesis. J Am Chem Soc 2002; 124:5729-33. [PMID: 12010046 DOI: 10.1021/ja012576+] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cadmium selenide nanoparticles, prepared by known methods, were stabilized with functional phosphine oxide 1, then used to support the polymerization of cyclic olefins radially outward from the surface by ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The conversion of compound 1 into the new metathesis catalyst 3 by carbene exchange and the subsequent polymerization of cyclic olefins were observed spectroscopically by (1)H NMR to afford for example CdSe-polycyclooctene composite 6. Transmission electron micrographs on thin films of these composites showed good nanoparticle dispersion. This is in stark contrast to the substantial nanoparticle aggregation observed when similar polymerizations were performed in the presence of conventional TOPO-covered nanoparticles. The methods reported here to prepare composite product 6 are applicable to other cyclic olefins, and suggest that this chemistry will be useful for incorporating CdSe nanoparticles into a wide variety of polymer matrices.
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Affiliation(s)
- Habib Skaff
- Department of Polymer Science and Engineering, 120 Governors Drive, University of Massachusetts, Amherst, Massachusetts 01003, USA
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197
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Clark TD, Ferrigno R, Tien J, Paul KE, Whitesides GM. Template-directed self-assembly of 10-microm-sized hexagonal plates. J Am Chem Soc 2002; 124:5419-26. [PMID: 11996582 DOI: 10.1021/ja020056o] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This article presents a strategy for the fabrication of ordered microstructures using concepts of design inspired by molecular self-assembly and template-directed synthesis. The self-assembling components are 4-microm-thick hexagonal metal plates having sides 10 microm in length ("hexagons"), and each template consists of a 4-microm-thick circular metal plate surrounding a central cavity, the perimeter of which is complementary in shape to the external edges of a two-dimensional, close-packed array of hexagons. The hexagons and templates (collectively, "pieces") were fabricated via standard procedures and patterned into hydrophobic and hydrophilic regions using self-assembled monolayers (SAMs). Templated self-assembly occurs in water through capillary interactions between thin films of a nonpolar liquid adhesive coating the hydrophobic faces of the pieces. The hexagons tile the cavities enclosed by the templates, and the boundaries of the cavities determine the sizes and shapes of the assemblies. Curing the adhesive with ultraviolet light furnishes mechanically stable arrays having well-defined morphologies. By allowing control over the structures of the resulting aggregates, this work represents a step toward the development of practical methods for microfabrication based on self-assembly.
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Affiliation(s)
- Thomas D Clark
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA
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198
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Whitesides GM, Boncheva M. Beyond molecules: self-assembly of mesoscopic and macroscopic components. Proc Natl Acad Sci U S A 2002; 99:4769-74. [PMID: 11959929 PMCID: PMC122665 DOI: 10.1073/pnas.082065899] [Citation(s) in RCA: 911] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Self-assembly is a process in which components, either separate or linked, spontaneously form ordered aggregates. Self-assembly can occur with components having sizes from the molecular to the macroscopic, provided that appropriate conditions are met. Although much of the work in self-assembly has focused on molecular components, many of the most interesting applications of self-assembling processes can be found at larger sizes (nanometers to micrometers). These larger systems also offer a level of control over the characteristics of the components and over the interactions among them that makes fundamental investigations especially tractable.
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Affiliation(s)
- George M Whitesides
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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199
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Boncheva M, Gracias DH, Jacobs HO, Whitesides GM. Biomimetic self-assembly of a functional asymmetrical electronic device. Proc Natl Acad Sci U S A 2002; 99:4937-40. [PMID: 11959945 PMCID: PMC122698 DOI: 10.1073/pnas.032667599] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This paper introduces a biomimetic strategy for the fabrication of asymmetrical, three-dimensional electronic devices modeled on the folding of a chain of polypeptide structural motifs into a globular protein. Millimeter-size polyhedra-patterned with logic devices, wires, and solder dots-were connected in a linear string by using flexible wire. On self-assembly, the string folded spontaneously into two domains: one functioned as a ring oscillator, and the other one as a shift register. This example demonstrates that biomimetic principles of design and self-organization can be applied to generate multifunctional electronic systems of complex, three-dimensional architecture.
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Affiliation(s)
- Mila Boncheva
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
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200
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Jonas U, del Campo A, Krüger C, Glasser G, Boos D. Colloidal assemblies on patterned silane layers. Proc Natl Acad Sci U S A 2002; 99:5034-9. [PMID: 11959954 PMCID: PMC122717 DOI: 10.1073/pnas.082634799] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2001] [Indexed: 11/18/2022] Open
Abstract
The site-selective assembly of colloidal polymer particles onto laterally patterned silane layers was studied as a model system for the object assembly process at mesoscale dimensions. The structured silane monolayers on silicon oxide substrates were fabricated by a combination of liquid- and gas-phase deposition of different trialkoxysilanes with a photolithographic patterning technique. By using this method various types of surface functionalizations such as regions with amino functions next to areas of the bare silica surface or positively charged regions of a quaternary ammonium silane surrounded by a hydrophobic octadecylsilane film could be obtained. Furthermore, a triethoxysilane with a photoprotected amino group was synthesized, which allowed direct photopatterning after monolayer preparation, leading to free NH(2) groups at the irradiated regions. The different silane monolayer patterns were used to study the surface assembly behavior of carboxylated methacrylate particles by optical and scanning electron microscopy. In dependence of the assembly conditions (different surface functionalizations, pH, and drying conditions), a selective preference of the particles for a specific surface type versus others was found. Site-specific colloid adsorption could be observed also on the photosensitive silane layers after local deprotection with light. From the photosensitive silane and positively charged ammonium silane, molecularly mixed monolayers were prepared, which allowed particle adsorption and photoactivation within the same monolayer as shown by fluorescence labeling.
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Affiliation(s)
- Ulrich Jonas
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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