The nanostructured materials group is currently focused on three main sub-areas:

• Nucleation control
  There is an increasing realization of importance of nucleation in (i) the synthesis of nanostructured materials, (ii) the ability to gain improved control of microstructure and nanostructure, by deliberately introducing particles (inoculants) that can promote nucleation and by manipulating the coupling of different stochastic processes, and (iii) the importance of nucleation in biological and medical processes, such as biomineralization, ice formation and the nucleation and growth of kidney stones in living systems for example.

  Washington University is ideally suited to make significant contributions in the emerging field of nucleation control. Several faculty members in the Physics and Mechanical Engineering Departments already study nucleation processes in the liquid, solid and vapor phases. We are combining that in-house expertise with unique experimental facilities and expertise located in the Physics Department, and computational modeling capabilities existing in the Chemistry Department.

• Single-nanostructure spectroscopy and transport
  Single-nanostructure spectroscopic methods have now emerged that have revealed new and unexpected phenomena in binary quantum dots, which we are applying to studies of quantum wires and to new ternary semiconductor quantum dots. A series of quantum wires composed of II-VI and III-V semiconductors, such as InP, GaAs, CdSe, CdS, and CdTe, as well as new ternary Zn_y-xCd_xSe_y quantum dots are studied by single-nanostructure imaging and spectroscopy. Single-nanowire transport measurements are also providing important insights about the electrical properties of quantum nanostructures. This research is enabled by a collaboration combining synthetic (Buhro, Hayes), spectroscopic (Loomis), and nanofabrication (Solin) expertise to enable single-nanostructure studies at Washington University.

  Until recently, most spectroscopic studies of quantum confinement were conducted on ensembles or dispersions of nanostructures, resulting in the loss of information through spectral broadening and averaging of orientational effects. Single-nanostructure spectroscopic methods have now emerged that have revealed new and unexpected phenomena in quantum dots which we apply to studies of quantum wires. Single-nanowire transport measurements are also providing important insights about the electrical properties of quantum nanostructures.

• Environmental impact of nanoparticles
  Engineered nanoparticles will be important building blocks for nanoscale materials and devices. Several synthesis routes are now being considered by industry for large scale production of nanomaterials. However, the responsible development of new technologies requires a sound assessment of their environmental and societal impacts. Given the increased public awareness of the potential risks and ethical issues involved with new technologies, nanotechnology research must proceed under the premise of creating environmentally sound technologies from their inception, rather than rushing to new developments and only years or decades later recognizing deleterious consequences.

  The specific short-term objectives of this work are to:

  • Synthesize pristine and doped titanium dioxide with controlled size, composition and morphology,
  • Characterize the as-synthesized samples to establish the surface characteristics that may influence biological activity,
  • Establish the bioavailability through solubilization studies of the nanoparticles as a function of composition, size and morphology, and
  • Collaborate with toxicologists to establish the cellular response to these nanoparticles.