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.

Quasicrystalline nanocrystal superlattice with partial matching rules.

Abstract: Expanding the library of self-assembled superstructures provides insight into the behaviour of atomic crystals and supports the development of materials with mesoscale order. Here we build on recent findings of soft matter quasicrystals and report a quasicrystalline binary nanocrystal superlattice that exhibits correlations in the form of partial matching rules reducing tiling disorder. We determine a three-dimensional structure model through electron tomography and direct imaging of surface topography. The 12-fold rotational symmetry of the quasicrystal is broken in sublayers, forming a random tiling of rectangles, large triangles and small triangles with 6-fold symmetry. We analyse the geometry of the experimental tiling and discuss factors relevant for the stabilization of the quasicrystal. Our joint experimental-computational study demonstrates the power of nanocrystal superlattice engineering and further narrows the gap between the richness of crystal structures found with atoms and in soft matter assemblies.

Binary and ternary superlattices self-assembled from colloidal nanodisks and nanorods.

Abstract: Self-assembly of multicomponent anisotropic nanocrystals with controlled orientation and spatial distribution allows the design of novel metamaterials with unique shape- and orientation-dependent collective properties. Although many phases of binary structures are theoretically proposed, the examples of multicomponent assemblies, which are experimentally realized with colloidal anisotropic nanocrystals, are still limited. In this report, we demonstrate the formation of binary and ternary superlattices from colloidal two-dimensional LaF3 nanodisks and one-dimensional CdSe/CdS nanorods via liquid interfacial assembly. The colloidal nanodisks and nanorods are coassembled into AB-, AB2-, and AB6-type binary arrays determined by their relative size ratio and concentration to maximize their packing density. The position and orientation of anisotropic nanocrystal building blocks are tightly controlled in the self-assembled binary and ternary lattices. The macroscopic orientation of the superlattices is further t...

Engineering catalytic contacts and thermal stability: gold/iron oxide binary nanocrystal superlattices for CO oxidation.

Abstract: Well-defined surface, such as surface of a single crystal, is being used to provide precise interpretation of catalytic processes, while the nanoparticulate model catalyst more closely represents the real catalysts that are used in industrial processes. Nanocrystal superlattice, which combines the chemical and physical properties of different materials in a single crystalline structure, is an ideal model catalyst, that bridge between conventional models and real catalysts. We identify the active sites for carbon monoxide (CO) oxidation on Au-FeOx catalysts by using Au-FeOx binary superlattices correlating the activity to the number density of catalytic contacts between Au and FeOx. Moreover, using nanocrystal superlattices, we propose a general strategy of keeping active metals spatially confined to enhance the stability of metal catalysts. With a great range of nanocrystal superlattice structures and compositions, we establish that nanocrystal superlattices are useful model materials through which to exp...

Tunable Plasmonic Coupling in Self-Assembled Binary Nanocrystal Superlattices Studied by Correlated Optical Microspectrophotometry and Electron Microscopy

Abstract: We study the plasmonic properties of self-assembled binary nanocrystal superlattices (BNSLs) using correlated optical microspectrophotometry and electron microscopy performed on individual BNSL domains. The strength of near-field couplings between adjacent plasmonic nanocrystals (NCs) can be systematically engineered by varying the NC size, composition, and the lattice symmetry of BNSLs, leading to broadband spectral tunability of the collective plasmonic response of BNSLs across the entire visible spectrum. Self-assembled multicomponent NC superlattices represent a versatile platform for the rational design of macroscopic three-dimensional plasmonic metamaterials with emergent optical characteristics.

Heterogeneous catalysts need not be so "heterogeneous": monodisperse Pt nanocrystals by combining shape-controlled synthesis and purification by colloidal recrystallization.

Abstract: Well-defined surfaces of Pt have been extensively studied for various catalytic processes. However, industrial catalysts are mostly composed of fine particles (e.g., nanocrystals), due to the desire for a high surface to volume ratio. Therefore, it is very important to explore and understand the catalytic processes both at nanoscale and on extended surfaces. In this report, a general synthetic method is described to prepare Pt nanocrystals with various morphologies. The synthesized Pt nanocrystals are further purified by exploiting the "self-cleaning" effect which results from the "colloidal recrystallization" of Pt supercrystals. The resulting high-purity nanocrystals enable the direct comparison of the reactivity of the {111} and {100} facets for important catalytic reactions. With these high-purity Pt nanocrystals, we have made several observations: Pt octahedra show higher poisoning tolerance in the electrooxidation of formic acid than Pt cubes; the oxidation of CO on Pt nanocrystals is structure insensitive when the partial pressure ratio p(O2)/p(CO) is close to or less than 0.5, while it is structure sensitive in the O(2)-rich environment; Pt octahedra have a lower activation energy than Pt cubes when catalyzing the electron transfer reaction between hexacyanoferrate (III) and thiosulfate ions. Through electrocatalysis, gas-phase-catalysis of CO oxidation, and a liquid-phase-catalysis of electron transfer reaction, we demonstrate that high quality Pt nanocrystals which have {111} and {100} facets selectively expose are ideal model materials to study catalysis at nanoscale.

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.