Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

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New approaches to nanofabrication: molding, printing, and other techniques.

In Vitro Cytotoxicity of Nanoparticles in Mammalian Germline Stem Cells

Chemistries that Facilitate Nanotechnology Kim E. Sapsford,† W. Russ Algar, Lorenzo Berti, Kelly Boeneman Gemmill,‡ Brendan J. Casey,† Eunkeu Oh, Michael H. Stewart, and Igor L. Medintz*,‡ †Division of Biology, Department of Chemistry and Materials Science, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, United States ‡Center for Bio/Molecular Science and Engineering Code 6900 and Division of Optical Sciences Code 5611, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States College of Science, George Mason University, 4400 University Drive, Fairfax, Virginia 22030, United States Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento, California 95817, United States Sotera Defense Solutions, Crofton, Maryland 21114, United States

Functionalizing nanoparticles with biological molecules: developing chemistries that facilitate nanotechnology.

Selective non-covalent interactions have been widely exploited in solution-based chemistry to direct the assembly of molecules into nanometre-sized functional structures such as capsules, switches and prototype machines1,2,3,4,5. More recently, the concepts of supramolecular organization have also been applied to two-dimensional assemblies on surfaces6,7 stabilized by hydrogen bonding8,9,10,11,12,13,14, dipolar coupling15,16,17 or metal co-ordination18. Structures realized to date include isolated rows8,13,14,15, clusters9,10,18 and extended networks10,11,12,17, as well as more complex multi-component arrangements16. Another approach to controlling surface structures uses adsorbed molecular monolayers to create preferential binding sites that accommodate individual target molecules19,20. Here we combine these approaches, by using hydrogen bonding to guide the assembly of two types of molecules into a two-dimensional open honeycomb network that then controls and templates new surface phases formed by subsequently deposited fullerene molecules. We find that the open network acts as a two-dimensional array of large pores of sufficient capacity to accommodate several large guest molecules, with the network itself also serving as a template for the formation of a fullerene layer.

Controlling molecular deposition and layer structure with supramolecular surface assemblies

Actin Motion on Microlithographically Functionalized Myosin Surfaces and Tracks

A novel route to molecular self-assembly: self-intermixed monolayer phases.

Control of actin moving trajectory by patterned poly(methylmethacrylate) tracks

Time evolution analysis of a 2D solid gas equilibrium: a model system for molecular adsorption and diffusion

The adsorption and the two-dimensional (2D) ordering of chloro[subphthalocyaninato]boron(III) (SubPc) on Ag(111) has been studied in detail by combined scanning tunneling microscopy and photoelectron spectroscopy at room temperature. SubPc is a polar, highly symmetric molecule, consisting of an extended aromatic system and a central B-Cl bond. When growing on Ag(111) an interesting phase behavior is observed for the first molecular layer of SubPc. At low coverage, below $\ensuremath{\approx}0.2$ monolayer (ML), a 2D lattice gas is present, whereas at medium coverage (on the order of 0.2--0.5 ML), 2D condensed molecular islands are observed in coexistence with the 2D lattice gas. In these condensed islands, the molecules assemble into a well-ordered honeycomb pattern. At higher coverage (approximately 0.5--0.9 ML) the molecules organize into a 2D hexagonal close-packed (hcp) pattern, in equilibrium with a dense 2D gas phase. In the honeycomb and in the hcp pattern, individual molecules are imaged with submolecular resolution, giving information on their orientation. For both the honeycomb and hcp patterns, islands with two different orientations of the superstructures with respect to the Ag(111) substrate are observed. In case of the honeycomb pattern, the two superstructures are enantiomorphic. The chirality of these layers originates in the loss of the symmetry of the metal surface upon adsorption of SubPc, while the molecules alone are intrinsically achiral. Based on different photoelectron spectroscopy experiments we conclude that the SubPc molecule is adsorbed on Ag(111) with its Cl atom towards the substrate and that the molecule remains intact. Finally, several aspects of the observed 2D condensed phases and the thermodynamic phase behavior are discussed with respect to the charge distribution and the adsorption physics and chemistry of the SubPc molecules.

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Hitoshi Suzuki

Papers

Actin Motion on Microlithographically Functionalized Myosin Surfaces and Tracks

A novel route to molecular self-assembly: self-intermixed monolayer phases.

Control of actin moving trajectory by patterned poly(methylmethacrylate) tracks

Time evolution analysis of a 2D solid gas equilibrium: a model system for molecular adsorption and diffusion

Adsorption and two-dimensional phases of a large polar molecule: Sub-phthalocyanine on Ag(111)