James K. Whitesell

Immunophenotyping using gold or silver nanoparticle‐polystyrene bead conjugates with multiple light scatter

BACKGROUNDnThe type of antibody-conjugated polystyrene (PS) latex beads for use as light scatter shift agents for targeted lymphocyte populations in whole blood has been expanded to include gold and silver nanoparticle-aminodextran-PS latex bead conjugates with antibodies. The linkers between antibody and colloidal metal were an aminotrithiol ligand or aminodextran polymer molecules.nnnMETHODSnA modified flow instrument, including forward light scatter (FS), side light scatter (SS), light scatter at other intermediate angle ranges, LMALS (10-20 degrees ) and UMALS (20-65 degrees ) was used for simultaneous bead probe measurements. A conventional flow cytometer was used in simultaneous bead-fluorescent marker experiments.nnnRESULTSnTwo mutually exclusive cell populations, CD4+ and CD8+ lymphocytes, have been simultaneously enumerated in blood by using a mixture of CD4-PS, CD8-Au-PS or CD4-Au-PS, CD8-PS beads, and one laser line, 633 nm, excitation. Similar measurements were made with mixtures of CD4-PS, CD8-Ag-PS or CD4-Ag-PS, CD8-PS beads. Also, simultaneous use of bead and fluorescent markers mixed with whole blood was demonstrated with CD4-PS beads and with the CD4-RD1/CD8-FITC dual marker.nnnCONCLUSIONSnEnumeration of CD4 and CD8 lymphocytes in whole blood by light scatter parameters only compared well with standard analyses with fluorescent markers. In simultaneous bead-fluorescent marker labeling of lymphocytes, the labeled bead had to be mixed first with cells in whole blood.

α-Helical Polypeptide Films Grown From Sulfide or Thiol Linkers on Gold Surfaces

We prepared two new linkers, S-functionalized adamantane derivatives 2 and 3, which bind as monolayers on polycrystalline gold. From these surface anchors, both L- and D-isomers of alanine can be grown as thin films of α-helical polypeptides directed from the gold surface by using the appropriate N-carboxyalanine anhydride. FT-IR Studies show that these layers are roughly 1000-A thick and that, under the same growth conditions, the L-polypeptide layers grow at a rate ca. 30% greater than that of the non-natural D-amino acid. X-Ray photoelectron spectroscopy studies show that, upon equilibration, all three S-atoms of the sulfide moieties of 2 are bound to the gold surface, and that, on average, three of the four thiols of 3 are chemoadsorbed. The essential role of H2O on the surface of these films as a necessary component in these gas-phase polymerization reactions is demonstrated.

The influence of core size on electronic coupling in shell–core nanoparticles: gold clusters capped with pyrenoxylalkylthiolate

The mean size of the metallic core of monolayer-protected gold clusters densely capped with 9-(1-pyrenoxyl)octane-1-thiol or 1-dodecanethiol can be adjusted by controlling the thiol/HAuCl4 ratio during synthesis. Upon reduction of tetrachloroaurate by NaBH4, lower mean metal core diameters were attained in those composites prepared from mixtures with higher thiol/Au ratios. The efficiency of electronic coupling between the core metal cluster and pyrenyl groups appended as an outer shell in this size-graded family was studied by absorption and fluorescence spectroscopy. The observed emission intensity from the bound fluorophores is independent of the gold core size.

Photocatalytic oxidation of n-octanol in aerated supercritical CO2 on hydrophobic TiO2

Supercritical CO2 (scCO2) has been used as a reaction medium for the photocatalytic oxidative degradation of n-octanol on a partially desilanized hydrophobic suspension of TiO2 as photocatalyst. Hydrophobic sites on the catalyst surface are necessary to maintain a sustained suspension, and hence surface-mediated interfacial electron exchange, in this non-polar medium. The reaction rates for photooxidative degradation, ultimately to complete mineralization, depend only weakly on temperature and pressure of the supercritical fluid near the critical point. Product distributions were monitored in situ by on-line gas chromatographic analysis, which provides a convenient and rapid method for comparisons and optimization of the reaction conditions.

Nanoscaled Components for Improved Efficiency in a Multiplanel Photocatalytic Water-Splitting System

The goal of this program was to construct a multicell photochemical device for the direct conversion of solar energy directly to hydrogen by water splitting. We have fabricated a practical photolytic system for quantum efficient production of hydrogen. Our approach is based on the assembly of a multi-component integrated system for direct photocatalytic splitting of water for the efficient production of hydrogen. We propose to produce hydrogen as an energy source that is cost competitive with fossil fuels and without the concomitant production of greenhouse gases. The concept is quite straightforward. In order to achieve the over potential required for direct water splitting, the device is composed of multiple dye-sensitized cells directly linked in series, as illustrated in the figure below. The advantage of this concept is that each cell need contribute only a fraction of the overall potential required for water splitting, thus permitting device engineering to maximized efficiently without regard to electric potential. Progress and barriers to practical application will be described.

Functionalized Nanoparticles and Surfaces for Controlled Chemical Catalysis and Effective Light Harvesting

We have prepared a range of such arrays as key components for biotechnology and photonic applications. These involve self-assembled arrays of increasing complexity with three-dimensionally disposed multilayer interactions. These arrays also include dendrimers as the distinguishing structural building blocks. These photoactive integrated systems have a regular, highly-branched, three-dimensional architecture. Structural modifications of these units include variation of the core, bridging layers, and terminal groups. These modifications result in a large array of dendritic molecules with potential applications for light harvesting.

Multiple Substituent Shift Additivity

The relatively simple table of shift effects provided in Chapter 1 can be used to make approximate predictions of chemical shifts which in turn are useful in making first inspection assignments between carbons and absorptions. It is of course implicit in such a treatment that the magnitude of the shift-of-shift effect for a substituent be relatively independent of the presence of other groups. Thus, the shift of a given carbon might be considered to be the sum of the independent effects of all of the neighboring groups. This does indeed hold true in those situations where substituents do not directly interact with each other and where the conformation of the system is relatively constant. In theory it should be possible to arrive at predicted spectra for all possible isomers of an unknown compound and comparison of these with the observed values would narrow the possible candidates to one or at most two choices. However, it should be clear from the discussion in Chapter 2 that the magnitude of the shift effect of a substituent varies with the carbon framework to which it is attached, and therefore, no simple collection of generalized substituent effects will provide accurate predictions in all situations. Nonetheless, with appropriate spectral data for model compounds available, the total shift effect of several, noninteracting substituents can be predicted to be the sum of the Δδ effects for each individual substituent.

Bicyclo[3.2.2]nonanes

The problem of nomenclature is avoided here because, as a result of the scarcity of data, all data can be displayed on three-dimensional representations. Except in obvious cases, conformational biases should not be assumed from the drawings.

Fundamental Effects on Carbon Shifts

The power of carbon NMR spectroscopy for the solution of structural problems in organic chemistry can be attributed mainly to a single phenomenon — that, in most cases, the total effect on chemical shifts due to the presence of a large number and variety of substituents can be predicted to be the sum of the effects of the individual groups. It is this “substituent additivity” that sets carbon spectroscopy distinctly apart from proton spectroscopy. For example, the chemical shift values for the indicated carbons in ethane, propane, butane, and pentane progress in the order: 6.5, 16.3, 24.8, 34.2 δ[l].

Mono- and Bicyclic Systems

The concept of shift additivity that was developed in Chapter 1 with acyclic systems can be extended to cover cyclic arrays as well. Unfortunately, each ring system has unique features and a relatively simple but “universal” set of Δδ values such as that found in Table 1–1 will be too general to provide accurate predictions for mono- and especially polycyclic systems. It is for this reason that we have gathered the extensive sets of carbon shift data that will be found in the following chapters that individually cover virtually all of the bicyclic ring systems that are commonly used in synthesis. Thus, while the Δδ values of substituents differ from one system to another and even between positions on a given framework, the majority of these values will be found in this book. In addition, these Δδ values can be applied directly to tri- and tetracyclic systems by an analysis that treats each local area as part of bicyclic subunit.