Daniel L. Feldheim

Metal Nanoparticles Synthesis, Characterization, and Applications

Introduction to particle synthesis, optical, and electronic properties solution-phase nanocluster synthesis and mechanisms of formation magic number metal clusters electrochemical synthesis of high aspect ratio gold particles template synthesis of metal nanostructures synthesis of metal nanoclusters using dendrimer templates nanosphere lithography electrochemistry of monolayer protected gold clusters modelling of nanoparticle optical properties hyper-Raleigh scattering of nanoparticles nanoparticle single electron devices DNA detection using gold nanoparticles conductance-based nanoparticle chemical sensors surface plasmon resonance detection of biomolecules synthesis of conductive polymer-gold particle composites optical properties of complex metal nanostructures si-coated nanoparticles nanoparticle arrays mixed particle arrays nanoparticles in electronic devices.

Gold Nanoparticles as Templates for the Synthesis of Hollow Nanometer-Sized Conductive Polymer Capsules**

By Stella M. Marinakos, DavidA. Shultz,* andDaniel L. Feldheim*The organization of materials on the nanoscale is an im-portant objective of chemists and materials scientists. Con-trol over the spatial arrangement of nanoscopic buildingblocks often leads to new materials with chemical, mechan-ical, optical, or electronic properties distinctly differentfrom those of their component parts.

Selection of biomolecules capable of mediating the formation of nanocrystals.

Biopolymers in the biosphere are well known to mediate the formation of a wide array of inorganic materials, such as bone, shells, lenses, and magnetic particles to name a few. Recently, in vitro experiments with biopolymers such as peptides, RNA, and DNA have shown that templating by these macromolecules can yield a variety of materials under mild reaction conditions. The primary sequence of the biopolymer can be viewed as a proteomic or genomic signature for the templating of an inorganic material from defined metal precursors and reaction conditions. Together with the rapid advances in inorganic particle synthesis by other combinatorial methods, these bioinspired in vitro materials experiments may provide additional insights into possible inorganic materials yet to be discovered and subsequently synthesized by conventional methods. Some of the concepts important to understanding the crystallization phenomena occurring during biopolymer mediation are discussed. A simple kinetic model is provided in the context of known biopolymer-mediated inorganic crystallizations.

Near‐IR Absorption Spectra for the Buckminsterfullerene Anions: an Experimental and Theoretical Study

Abstract : C60 can exist in a number of oxidation states including C60(1-), C60(2-) and C60(3-). Ultraviolet-visible absorption data have been described. Near-infrared absorption data have not been presented for any of the oxidation states of C60. we have discovered that this is a serious oversight, because near-IR absorption peaks which are unique to C60(1-) C60(2-) and C60(3-) are observed upon one, two and three electron electrochemical reductions of C60. We have rationalized the energies and intensities of these electronic absorptions based on modifications of the known molecular orbital diagram for C60. The near-IR absorptions reported here should provide a clear and unambiguous route for determining the oxidation state of C60 in solution.

Switchable gate membranes. Conducting polymer films for the selective transport of neutral solution species

Abstract The conductive polymers poly(3-methylthiophene) and poly(N-methylpyrrole) have been explored for their use as “gate” for the separation of neutral solutes. The diffusion of a few common solvents through the films is found to depend on the oxidation state of the polymers and the dopant anion. Scanning electron micrographs show significant macroscopic morphological differences between the oxidized and reduced polymers which may be linked to the transport properties of the films.

Gastrointestinal bioavailability of 2.0 nm diameter gold nanoparticles.

The use of gold nanoparticles as imaging agents and therapeutic delivery systems is growing rapidly. However, a significant limitation of gold nanoparticles currently is their low absorption efficiencies in the gastrointestinal (GI) tract following oral administration. In an attempt to identify ligands that facilitate gold nanoparticle absorption in the GI tract, we have studied the oral bioavailability of 2.0 nm diameter gold nanoparticles modified with the small molecules p-mercaptobenzoic acid and glutathione, and polyethylene glycols (PEG) of different lengths and charge (neutral and anionic). We show that GI absorption of gold nanoparticles modified with the small molecules tested was undetectable. However, the absorption of PEGs depended upon PEG length, with the shortest PEG studied yielding gold nanoparticle absorptions that are orders-of-magnitude larger than observed previously. As the oral route is the most convenient one for administering drugs and diagnostic reagents, these results suggest that short-chain PEGs may be useful in the design of gold nanoparticles for the diagnosis and treatment of disease.

Synthesis and Catalytic Activity of Transition Metal Polymers Containing Alkane‐Linked Bipyridine and Terpyridine Ligands

Transition metal polymers containing alkane-linked bi- and ter-pyridine ligands have been prepared and studied as thin films deposited on electrode surfaces. The cobalt and iron containing polymers exhibit electrochemical behavior similar to that of the corresponding monomers and to polymers formed by reductive polymerization of vinyl-containing monomers (in cases where such polymers exist). Despite these similarities, in several instances the present polymers exhibit distinctly different behavior with regard to their ability to catalyze the reduction of CO 2 and O 2 when compared to soluble monomers and other supposedly similar polymers. Consideration is given to potential structural differences that may give rise to differences in catalytic activity