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C.J. Brinker - Publications and Proceedings

ISI Top 20 Most Cited Papers in Materials Science

Most Cited Publication in the Last Decade

Publications

Proceedings

Featured Publications

Integration of a Close-Paced Quantum Dot Monolayer with a Photonic-Crystal Cavity via Interfacial Self-Assembly and Transfer

Xiong, S; Miao, X; Spencer, J; Khiprin, C; Luk, TS; Brinker, CJ.

Small, September 2010; p. 1-4
[ PDF ] [ Supplementary Info]

Nanoparticle (NP) assembly into ordered 2- and 3-D superlattices has stimulated enormous recent interest as a means to create new artificial solids whose electronic, magnetic, and optical behaviors can be tailored by the size dependent properties of the individual NPs mediated by coupling interactions with neighboring NPs, suggesting applications in a diverse range of technologies including photovoltaics, sensors, catalysis, and magnetic storage. To date superlattice assembly has been demonstrated for monosized, binary, and even ternary systems, allowing development and interrogation of a range of collective behaviors: electron transport within 2- and 3-D arrays of Coulomb islands, Forster resonance energy transfer between superlattice monolayers in close proximity, switchable optical properties through regulation of NP d-spacing, and new magnetic behaviors based on binary superlattices. Superlattice fabrication is performed principally by droplet evaporation or convective assembly on an inclined plate. These techniques are often slow, restricted in the size and topography of the substrate, and result in van der Waals solids with limited mechanical behaviors. To address these issues, we recently reported a general, rapid method to prepare large area, freestanding,
NP/polymer monolayer superlattices by interfacial NP assembly within a polymer fi lm on a water surface.
Although it is well known that the Langmuir-Blodgett tech- nique has been used to produce well-controlled nano particle films, our ultra-thin superlattices are highly robust and transferable to arbitrary substrates, owing to the polymer supporting layer.

 

Figure 1. a) Schematic of the evaporation induced interfacial assembly and transfer process. b) Film transfer to the photonic crystal cavity by picking process results in a monolayer where the QDs are in close contact with the photonic crystal surface. c) For lifting, the QDs are about 20 ∼ 50-nm away from the photonic crystal in the vertical direction. The AFM images (d) show the surface topography for the original vapor-side
interface (AFM image of lifted monolayer) and for the original water-side interface. The dimension of the scanned image is 250 × 250 nm.

 

DNA Translocation Through an Array of Kinked Nanopores

Chen, Z; Jiang, YB; Dunphy, DR; Adams, DP; Hodges, C; Liu, N; Zhang, N; Xomeritakis, G; Jin, X; Aluru, NR; Gaik, SJ; Hillhouse, HW; Brinker, CJ

Nature Materials, Jul 23, 2010; p. 667-675
[ PDF ] [ Supplementary Info]

Synthetic solid-state nanopores are being intensively investigated as single-molecule sensors for detection and
characterization of DNA, RNA and proteins. This field has been inspired by the exquisite selectivity and flux demonstrated by natural biological channels and the dream of emulating these behaviours in more robust synthetic materials that are more readily integrated into practical devices. So far, the guided etching of polymer films, focused ion-beam sculpting, and electron-beam lithography and tuning of silicon nitride membranes have emerged as three promising approaches to define synthetic solid-state pores with sub-nanometre resolution. These procedures have in common the formation of nominally cylindrical or conical pores aligned normal to the membrane surface. Here we report the formation of ‘kinked’ silica nanopores, using evaporation-induced self-assembly, and their further tuning and chemical derivatization using atomic-layer deposition. Compared with ‘straight through’ proteinaceous nanopores of comparable dimensions, kinked nanopores exhibit up to fivefold reduction in translocation velocity, which has been identified as one of the critical issues in DNA sequencing. Additionally, we demonstrate an efficient two-step approach to create a nanopore array exhibiting nearly perfect selectivity for ssDNA over dsDNA. We show that a coarse-grained drift–diffusion theory with a sawtooth-like potential can reasonably describe the velocity and translocation time of DNA through the pore. By control of pore size, length and shape, we capture the main functional behaviours of protein pores in our solid-state nanopore system.

Salt-Induced Lipid Transfer between Colloidal Supported Lipid Bilayers

Kendall, EL; Mills, E; Liu, JW; Jiang, XM; Brinker, CJ; Parikh, AN

Soft Matter, July 2010 [PDF]

Interactions between closely apposed independent lipid bilayers are broadly relevant in many disparate lines of research. First, in living cells, lipid–lipid interactions represent some of the earliest defining events during membrane fusion—a universal mechanism for many vastly different biological processes. Examples span a broad range including exocytosis, organellar membrane trafficking, synaptic transmission, sperm–egg fertilization, enveloped viral infection, and biosynthetic vesicular transfection. Second, hybrid systems involving interactions between cells and synthetic lipid bilayers (vesicles and supported lipid bilayers) arise in the context of drug delivery as well as fundamental studies of cell signaling. Understanding how these delivery agents interact with native membranes of host cells is critical in optimally designing these vectors. Third, interactions between two synthetic membranes are also of interest in fundamental studies of interfacial interactions and can be exploited to create supported membrane systems that display compositional complexities.

Interaction between two populations of lipid coated microspheres in water. One group is coated in a bilayer of 99% POPC and 1% Texas Red- DHPE; the other is coated with 99% POPC and 1% NBD-PE. In the two image sequences shown we can follow the movement of the initially separate red (A–C) and green (D–F) fluorophores. In groupings of microspheres where two types of fluorophores are present we see a slow equilibration of fluorophore concentration between connected spheres. This sphere to sphere lipid transfer only occurs between directly contacting spheres as shown in confocal microscope images (G–I).

 

Confinement-Induced Quorum Sensing of Individual Staphylococcus Aureus Bacteria

Eric Carnes, DeAnna M Lopez, Niles P Donegan, Ambrose Cheung, Hattie Gresham, Graham Timmins, and C. Jeffrey Brinker

Nature Chemical Biology, November 2009 [PDF] [MEDIA COVERAGE]

It is postulated that in addition to cell density, other factors such as the dimensions and diffusional characteristics of the environment could influence quorum sensing (QS) and induction of genetic reprogramming. Modeling studies predict that QS may operate at the level of a single cell, but, owing to experimental challenges, the potential benefits of QS by individual cells remain virtually unexplored. Here we report a physical system that mimics isolation of a bacterium, such as within an endosome or phagosome during infection, and maintains cell viability under conditions of complete chemical and physical isolation. For Staphylococcus aureus, we show that quorum sensing and genetic reprogramming can occur in a single isolated organism. Quorum sensing allows S. aureus to sense confinement and to activate virulence and metabolic pathways needed for survival. To demonstrate the benefit of confinement-induced quorum sensing to individuals, we showed that quorum-sensing bacteria have significantly greater viability over non-QS bacteria.

 

Figure 1 | Isolation of individual S. aureus within a nanostructured droplet. (a) Schematic of physical system (not to scale) showing a cell incorporated in an endosome-like lipid vesicle within a surrounding nanostructured lipid/silica droplet deposited on glass substrate. (b) Scanning electron microscopy image of the lipid-silica hemisphere confining the cell. The nanostructure maintains cell viability under dry external conditions and allows complete chemical and physical isolation of one cell from all others. (c,d) Plan-view optical microscope images of individual cells in droplets (large outer circular areas). Magnified areas show differential interference contrast (DIC ) image and red fluorescence image of individual stained, isolated cells (both c and d) and green fluorescence image of NBD -labeled lipid localization at cell surface (c) or localized pH (d, using Oregon Green pH-sensitive dye). We find that, within the droplet, the cells become enveloped in an endosome-like lipid vesicle (c) and establish a localized pH consistent with physiological early endosomal conditions (~5.5) (d). For further information regarding aerosolassisted droplet formation and lipid localization and pH establishment, see refs. 15 and 16.

 

Modulus–Density Scaling Behaviour and Framework Architecture of Nanoporous Self-Assembled Silicas

Hongyou Fan, Christopher Hartshorn, Thomas Buchheit, David Tallant, Roger Assink, Regina Simpson, Dave J. Kissel, Daniel J. Lacks, Salvatore Torquato, and C. Jeffrey Brinker

Nature Materials, June 2007, vol. 6, p.418-423 [PDF]

Natural porous materials such as bone, wood and pith evolved to maximize modulus for a given density1. For these threedimensional cellular solids, modulus scales quadratically with relative density2,3. But can nanostructuring improve on Nature’s designs? Here, we report modulus–density scaling relationships for cubic (C), hexagonal (H) and worm-like disordered (D) nanoporous silicas prepared by surfactantdirected self-assembly.Over the relative density range, 0.5 to 0.65, Young’s modulus scales as (density)n where n(C) <n(H) <n(D) <2, indicating that nanostructured porous silicas exhibit a structurespecific hierarchy of modulus values D < H < C. Scaling exponents less than 2 emphasize that the moduli are less sensitive to porosity than those of natural cellular solids, which possess extremal moduli based on linear elasticity theory4. Using molecular modelling and Raman and NMR spectroscopy, we show that uniform nanoscale confinement causes the silica framework of self-assembled silica to contain a higher portion of small, stiff rings than found in other forms of amorphous silica. The nanostructure-specific hierarchy and systematic increase in framework modulus we observe, when decreasing the silica framework thickness below 2 nm, provides a new ability to maximize mechanical properties at a given density needed for nanoporous materials integration5.

Logarithm of Young’s modulus versus logarithm of bulk density for self-assembled thin-film nanostructures C, H and D determined by nanoindentation. The power-law relationships of C, H and D films are E∼ ρ0.6 , E∼ ρ1.0 and E∼ ρ1.9, respectively. Modulus values were determined at a constant depth (less than 1/10 of the film thickness) where the modulus versus depth values were constant. This procedure should ensure modulus values comparable to bulk values18. Young’s modulus was calculated from the nanoindentation modulus according to Er = E(1−ν2 ), where E is Young’s modulus and ν is Poisson’s ratio. The standard deviation was determined from the mean often measurements.

 

Cell-Directed Assembly of Lipid-Silica Nanostructures Providing Extended Cell Viability

Helen K. Baca, Carlee Ashley, Eric Carnes, Deanna Lopez, Jeb Flemming, Darren Dunphy, Seema Singh, Zhu Chen, Nanguo Liu, Hongyou Fan, Gabriel P. Lopez, Susan M Brozik, Magaret Werner-Washburne, C. Jeffrey Brinker

Science, Jul 21, 2006; vol. 313, p. 337-341
[ PDF ] [ Supplementary Info]

Living cells combine molecular recognition, amplification, and signal transduction in an extremely small ‘package’, making them ideally suited for miniaturized, standalone, environmental or physiological sensors. However, cellular integration into devices is problematic. Cells require functional bio/inorganic interfaces, benign synthesis conditions (1-3), and external fluidic support systems or immersion in buffer to avoid dehydration. Furthermore, as recently noted by Zhang (4), it is necessary to move beyond two-dimensional (2D) adhesion in dishes to 3D architectures that better represent the extracellular matrix, enabling cells to be surrounded by other cells, maintaining fluidic accessibility, and allowing development of 3D molecular or chemical gradients.

Fig. 1. S. cerevisiae organize a lipid-rich shell that interfaces coherently with the surrounding nanostructured silica host. (A) Confocal fluorescence image of immobilized cells with 1% substitution of the fluorescently labeled lipid analog, 1-hexanoyl-2-{6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl}-snglycero-3-phosphocholine (diC6PC-NBD). Brighter areas indicate preferential concentration of lipid around cells compared to the surrounding lipid/ silica host matrix. (B and C) TEM images of cell immobilized within nanostructured lipid/silica matrix by spin-coating directly on holey carboncoatedcopper grid. (D and E) SEM of cells immobilized in silica host prepared with (D) and without (E) lipids. The dark region around the cells in (D) corresponds to an area of high carbon/phosphorus concentration consistent with the presence of lipids (fig S2). In (E), the dark region is a crevice. Cells are firmly immobilized only when the lipid interface is present. In the absence of lipid, cell washout occurs and film cracking is prevalent.

 
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