Role of surface functionality in the electrochemical performance of silicon nanowire anodes for rechargeable lithium batteries.

We report the synthesis of silicon nanowires using the supercritical-fluid-liquid-solid growth method from two silicon precursors, monophenylsilane and trisilane. The nanowires were synthesized at least on a gram scale at a pilot scale facility, and various surface modification methods were developed to optimize the electrochemical performance. The observed electrochemical performance of the silicon nanowires was clearly dependent on the origination of the surface functional group, either from the residual precursor or from surface modifications.

Multi-photon excitation properties of CdSe quantum dots solutions and optical limiting behavior in infrared range.

Multi-photon absorption and excitation properties of CdSe quantum dots in hexane with different dot-sizes have been investigated. The two- and three-photon absorption (2PA and 3PA) coefficients were measured by using ~160-fs laser pulses at wavelengths of ~775-nm and ~1300-nm, respectively. The dependence of one-, two- and three-photon induced fluorescence spectra as well as their double-exponential decay on the dot-sizes was studied.

Diacyllipid micelle-based nanocarrier for magnetically guided delivery of drugs in photodynamic therapy.

We report the design, synthesis using nanochemistry, and characterization of a novel multifunctional polymeric micelle-based nanocarrier system, which demonstrates combined function of magnetophoretically guided drug delivery together with light-activated photodynamic therapy. Specifically, the nanocarrier consists of polymeric micelles of diacylphospholipid-poly(ethylene glycol) (PE-PEG) coloaded with the photosensitizer drug 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH), and magnetic Fe3O4 nanoparticles. The nanocarrier shows excellent stability and activity over several weeks.

Aqueous ferrofluid of magnetite nanoparticles: Fluorescence labeling and magnetophoretic control.

A method is presented for the preparation of a biocompatible ferrofluid containing dye-functionalized magnetite nanoparticles that can serve as fluorescent markers. This method entails the surface functionalization of magnetite nanoparticles using citric acid to produce a stable aqueous dispersion and the subsequent binding of fluorescent dyes to the surface of the particles. Several ferrofluid samples were prepared and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), BET surface area analysis, transmission electron microscopy (TEM), and SQUID magnetometry.

A general approach to binary and ternary hybrid nanocrystals.

We describe and demonstrate a general strategy for engineering binary and ternary hybrid nanoparticles based on spontaneous epitaxial nucleation and growth of a second and third component onto seed nanoparticles in high-temperature organic solutions. Multifunctional hybrid nanoparticles that combine magnetic, plasmonic, and semiconducting properties and that are tunable in size and morphology can be realized, as demonstrated for combinations of Au, Fe3O4 and PbS or PbSe. The properties of each component within the hybrids can be modulated strongly by the conjugating component(s) aided by the coherent interfaces between them.

Shape control of PbSe nanocrystals using noble metal seed particles.

We demonstrate that the shape of PbSe nanocrystals can be controlled systematically by seeding their growth with noble metal nanoparticles (Au, Ag, or Pd) and varying the seed and precursor concentrations. Cylinders (quantum rods), cubes, crosses, stars, and branched structures were produced in high yield at 150 degrees C in reaction times of a few minutes. Although their absorption spectrum does not exhibit sharp features, the quantum rods exhibit significant photogeneration efficiency, enabling infrared sensitization of a polymeric photoconductive nanocomposite.