Research Interests

Silicon is the second most abundant element in the Earth''s crust, and is an essential component of a myriad of products including semiconductors, glasses and ceramics, elastomers and resins, optical fibers and coatings, and insulators. The energy barrier(s) to nucleation and growth of silica are high, and therefore current technologies for synthesis of these materials require high concentrations of silicic acid, extreme temperatures and pressures, and the use of caustic chemicals. In contrast, living organisms are able to mold amorphous silica into extremely elaborate and controlled nanostructures under comparably mild conditions (e.g. low concentrations of silicic acid and electrolyte, near neutral pH, and ambient temperature and pressure; see Figure 1).

Figure 1: Electron Micrographs of marine datioms

Clearly, silicifiers employ complex biochemical strategies that allow the energy landscape to be manipulated, such that the energetic barriers to nucleation and growth of are minimized during the organism''s growth stage(s). Tremendous strides towards understanding the controlled synthesis of amorphous silica stand to be made through investigation of biosilicification processes.

My research investigates the thermodynamic and kinetic barriers to the nucleation of biogenic silica, using self-assembled monolayers (SAMs) of n-alkanethiols as a proxy for the biological nucleation environment (Figure 2).

Figure 2: Schematic SAM system / model nucleation environment

Techniques such as microcontact printing (Figure 3) and dip-pen nanolithography are being used to deposit micropatterned monolayers n-alkanethiols on Au(111). The resulting surfaces are chemically similar to biological environments where nucleation of biogenic silica likely occurs.

Figure 3 : Frictiional image of a patterned SAM on Au(111)

In situ observation of growing nuclei is possible with scanning probe microscopy (SPM)