There is a significant current interest in development of new techniques for direct characterization the intracellular redox state and high-resolution imaging living cells. We used nanometer-sized amperometric probes combination with scanning electrochemical microscope (SECM) to carry out spatially resolved experiments cultured human breast With tip radius approximately 1,000 times smaller than that cell, an probe can penetrate cell travel inside it without apparent damage membrane. The data...

The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In it often necessary inject material high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable molecules. All techniques currently used for microinjection plagued by two common problems: the relatively large injector size volume injected fluid, poor control amount material. Here...

Over the last 2 decades, scanning electrochemical microscopy (SECM) has been extensively employed for topographic imaging and mapping surface reactivity on micrometer scale. We used flat, polished nanoelectrodes as SECM tips to carry out feedback mode of various substrates with nanoscale resolution. Constant-height constant-current images plastic Au compact disc surfaces more complicated objects (computer chips wafers) were obtained. The possibility simultaneous topography was demonstrated....

The transfers of hydrophilic ions between aqueous and organic phases are ubiquitous in biological technological systems. These energetically unfavorable processes can be facilitated either by small molecules (ionophores) or ion-transport proteins. In absence a facilitating agent, ion-transfer reactions assumed to "simple", one-step processes. Our experiments at the nanometer-sized interfaces water neat solvents showed that generally accepted mechanism cannot explain important features...

The effect of water content in a low polarity organic phase on transfers hydrophobic and hydrophilic ions across the liquid/liquid interface was investigated by nanopipet voltammetry. It shown recently (J. Am. Chem. Soc. 2006, 128, 15019) that can be transferred to less polar solvents such as 1,2-dichloroethane (DCE) only presence counterions facilitate processes. addition trace amounts neat DCE induces but practically does not affect species. Although conductivity decreases upon it, rates...

The rates of electron transfer (ET) reactions at the water/ionic liquid (IL) interface have been measured for first time using scanning electrochemical microscopy. standard bimolecular rate constant interfacial ET between ferrocene dissolved in 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and aqueous ferricyanide (0.4 M-1 cm s-1) was found to be approximately 30 times higher than corresponding water/1,2-dichloroethane interface. driving force dependence investigated over a...

Nanopipet voltammetry was used for the first study of ion transfer (IT) reactions between aqueous solutions and neat organic solvents. An extremely wide (∼10 V) polarization window obtained with no electrolyte added to phase allows one probe charge reactions, which are not normally accessible by electrochemical techniques, example, l-alaninamide cation from water 1,2-dichloroethane (DCE). While anions (e.g., chloride) relatively hydrophobic cations tetraalkylammonium ions) can be transferred...

Molecular partitioning and electron-transfer kinetics have been studied at the ionic liquid/water (IL/water) interface by scanning electrochemical microscopy (SECM). The liquid C8mimC1C1N is immiscible with water forms a nonpolarizable when in contact it. Partitioning of ferrocene (Fc) across IL/water was SECM found to be kinetically fast partition coefficient CIL/CW 2400:1. value measured under quasi-steady-state conditions without waiting for complete solute equilibration. To investigate...

We propose a method for interactively controlling multi-species atomic and molecular systems with incoherent light. The technique is referred to as shaped light control (SILC), which entails dynamically tailoring the spectrum of broadband source scale kinetics. Optimal SILC patterns can be discovered adaptive learning techniques where system’s observed response fed back adjustment aiming improve objective. To demonstrate this concept, we optimized optimally evolving hue in near-IR visible...

This work uses shaped femtosecond laser pulses to control the two-photon absorption (TPA) of coumarin 153 in a dispersive toluene medium. The medium reshapes pulse along optical path, and management this effect is used achieve spatial localization TPA. Other objectives were successfully implemented, including dual high resolution local optimization solutions these explored by means evolutionary single- multi-objective algorithms within laboratory feedback loop.

A noncentrosymmetric nanocrystal can produce second-harmonic generation (SHG) and sum-frequency (SFG) upon interaction with a laser field. The SHG or SFG radiation depends on the orientation of as well field polarization, which allows for modulating second-order emission an arbitrarily oriented by specially tailoring polarization. We theoretically study signals produced nanocrystals driven broad-bandwidth pulses. Several simulations explore influence polarization temporal pulse profile....

Abstract not Available.

It is well known that gold nanorods (AuNRs) readily emit two-photon luminescence (TPL) when excited by a broad bandwidth laser pulse tuned to the AuNRs' localized surface plasmon resonance. The nature of mechanism (i.e., especially its degree coherence) under active debate. In this work, we measured TPL emission from single while varying angle θ between linearly polarized electric field and nanorod's orientation. Data were best fit with linear combination cos4 cos2 functions. While former...

Conventionally, bidirectional optogenetic switches are controlled with linear excitation (e.g., monochromatic CW light), which has serious limitations when there is a spectral overlap between the “on” and “off” states of switch. The crosstalk lowers selectivity photoactivation step, resulting in moderate photoequilibrium value poor dynamic range for Using stimulated depletion quenching (SDQ), nonlinear optical strategy similar to STED, we demonstrate enhanced on one side switch, thus...

We present a simple optical capability for generating spatially resolved chemical concentration maps of mixing fluids using chemically sensitive dye, 1-hydroxy-3,6,8-pyrenetrisulfonic acid, detected by planar laser induced fluorescence. To demonstrate an application this capability, we investigate the collision and pair microdroplets in air. The two are composed different fluids, methanol water, with dye initially droplet. When droplets collide process develops, fluorescence shifts from blue...

Abstract not Available.

The 2006 Edward G. Weston Summer Research Fellowship Summary Report

Double resonance excitation, where the energies of vibrational and electronic molecular transitions are combined in a single, sequential excitation process, was introduced 1970s but has only been recently applied to microscopy due immense progress Raman spectroscopy. The value technique is combining chemical selectivity IR or with much larger cross-sections transitions. Recently, it shown be particularly suited for detection identification chromophores at low concentrations presence spectral...