Christopher B. Murray

Bio: Christopher B. Murray is an academic researcher from University of Pennsylvania. The author has contributed to research in topics: Nanocrystal & Quantum dot. The author has an hindex of 88, co-authored 336 publications receiving 54410 citations. Previous affiliations of Christopher B. Murray include Universal Display Corporation & Lawrence Berkeley National Laboratory.

Cluster-Assembled Materials

Abstract: Cluster-assembled materials offer the ability to tune component properties, lattice parameters, and thus coupling of physical properties through the careful selection and assembly of building blocks. Multi-atom clusters have been found to exhibit physical properties beyond those available from the standard elements in the periodic table; classification of the properties of such clusters effectively enables expansion of the periodic table to a third dimension. Using clusters as superatomic building blocks for hierarchically assembled materials allows these properties to be incorporated into designer materials with tailored properties. Cluster-assembled materials are currently being explored and methods developed to control their design and function. Here, we discuss examples of building block syntheses, assembly strategies, and property control achieved to date.

Quasicrystalline order in self-assembled binary nanoparticle superlattices

Abstract: The discovery of quasicrystals in 1984 changed our view of ordered solids as periodic structures and introduced new long-range-ordered phases lacking any translational symmetry Quasicrystals permit symmetry operations forbidden in classical crystallography, for example five-, eight-, ten- and 12-fold rotations, yet have sharp diffraction peaks Intermetallic compounds have been observed to form both metastable and energetically stabilized quasicrystals; quasicrystalline order has also been reported for the tantalum telluride phase with an approximate Ta(16)Te composition Later, quasicrystals were discovered in soft matter, namely supramolecular structures of organic dendrimers and tri-block copolymers, and micrometre-sized colloidal spheres have been arranged into quasicrystalline arrays by using intense laser beams that create quasi-periodic optical standing-wave patterns Here we show that colloidal inorganic nanoparticles can self-assemble into binary aperiodic superlattices We observe formation of assemblies with dodecagonal quasicrystalline order in different binary nanoparticle systems: 134-nm Fe(2)O(3) and 5-nm Au nanocrystals, 126-nm Fe(3)O(4) and 47-nm Au nanocrystals, and 9-nm PbS and 3-nm Pd nanocrystals Such compositional flexibility indicates that the formation of quasicrystalline nanoparticle assemblies does not require a unique combination of interparticle interactions, but is a general sphere-packing phenomenon governed by the entropy and simple interparticle potentials We also find that dodecagonal quasicrystalline superlattices can form low-defect interfaces with ordinary crystalline binary superlattices, using fragments of (3(3)4(2)) Archimedean tiling as the 'wetting layer' between the periodic and aperiodic phases

Monodisperse 3 d Transition-Metal (Co,Ni,Fe) Nanoparticles and Their Assembly intoNanoparticle Superlattices

Abstract: Magnetic colloids, or ferrofluids, have been studied to probe the fundamental size-dependent properties of magnetic particles and have been harnessed in a variety of applications. The magnetorheological properties of magnetic colloids have been exploited in high-performance bearings and seals. The deposition of magnetic dispersions on platters and tapes marked the earliest embodiments of magnet information storage. Magnetic particles enhance contrast in magnetic resonance imaging and promise future diagnostic and drug delivery applications. The need to explore the scaling limits of magnetic storage technology has motivated the preparation of size-tunable monodisperse magnetic nanoparticles with controlled internal structures. The study of these nanoparticles is critical to efforts to separate the role of defects from intrinsic, finite size effects.

Synergism in binary nanocrystal superlattices leads to enhanced p-type conductivity in self-assembled PbTe/Ag2Te thin films

Abstract: The ordered cocrystallization of nanoparticles into binary superlattices enables close contact of nanocrystals with distinct physical properties, providing a route to 'metamaterials' design. Here we present the first electronic measurements of multicomponent nanocrystal solids composed of PbTe and Ag(2)Te, demonstrating synergistic effects leading to enhanced p-type conductivity. First, syntheses of size-tuneable PbTe and Ag(2)Te nanocrystals are presented, along with deposition as thin-film nanocrystal solids, whose electronic transport properties are characterized. Next, assembly of PbTe and Ag(2)Te nanocrystals into AB binary nanocrystal superlattices is demonstrated. Furthermore, binary composites of varying PbTe-Ag(2)Te stoichiometry (1:1 and 5:1) are prepared and electronically characterized. These composites show strongly enhanced (conductance approximately 100-fold increased in 1:1 composites over the sum of individual conductances of single-component PbTe and Ag(2)Te films) p-type electronic conductivity. This observation, consistent with the role of Ag(2)Te as a p-type dopant in bulk PbTe, demonstrates that nanocrystals can behave as dopants in nanostructured assemblies.

Structural Characterization of Self-Assembled Multifunctional Binary Nanoparticle Superlattices

Abstract: Nanocrystals of different size and functionality (e.g., noble metals, semiconductors, oxides, magnetic alloys) can be induced to self-assemble into ordered binary superlattices (also known as opals or colloidal crystals), retaining the size tunable properties of their constituents. We have built a variety of binary superlattices from monodisperse PbS, PbSe, CoPt3, Fe2O3, Au, Ag, and Pd nanocrystals, mixing and matching these nanoscale building blocks to yield multifunctional nanocomposites (metamaterials). Superlattices with AB, AB2, AB3, AB4, AB5, AB6, and AB13 stoichiometry with cubic, hexagonal, tetragonal, and orthorhombic symmetries have been identified. Assemblies with the same stoichiometry can be produced in several polymorphous forms by tailoring the particle size and deposition conditions. We have identified arrays isostructural with NaCl, CuAu, AlB2, MgZn2, MgNi2, Cu3Au, Fe4C, CaCu5, CaB6, NaZn13, and cub-AB13 compounds emphasizing the parallels between nanoparticle assembly and atomic scale cr...

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。

Semiconductor Clusters, Nanocrystals, and Quantum Dots

Abstract: Current research into semiconductor clusters is focused on the properties of quantum dots-fragments of semiconductor consisting of hundreds to many thousands of atoms-with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size-dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

Abstract: Highly luminescent semiconductor quantum dots (zinc sulfide-capped cadmium selenide) have been covalently coupled to biomolecules for use in ultrasensitive biological detection. In comparison with organic dyes such as rhodamine, this class of luminescent labels is 20 times as bright, 100 times as stable against photobleaching, and one-third as wide in spectral linewidth. These nanometer-sized conjugates are water-soluble and biocompatible. Quantum dots that were labeled with the protein transferrin underwent receptor-mediated endocytosis in cultured HeLa cells, and those dots that were labeled with immunomolecules recognized specific antibodies or antigens.