Location: 218 Research I
Melechko's interests include catalytic co-synthesis of carbon nanostructures and the synthesis of metallic alloy nanoparticles
The primary effort is on the catalytic co-synthesis of carbon nanostructures and the synthesis of metallic alloy nanoparticles encapsulated within these nanostructures. Vertically aligned carbon nanofibers (VACNFs) are graphitic cylinders that are a few tens of nanometers in diameter and a few microns long. This research involves a study of the role of the catalyst material composition, crystallographic orientation, and shape on the atomic structure of the resulting carbon nanofibers; the link between the macroscopic parameters of the plasma enhanced chemical vapor deposition reactor environments and the atomic scale processes at the catalyst nanoparticles; the elucidation of the influence of the curved graphitic structure on the evolution of the shape and structure of the catalyst nanoparticle; the fundamental mechanisms of the nanoparticle self-assembly in a thin film dewetting process; and the alloy stability during and after co-synthesis and after post-synthesis annealing.
The integration of nanofibers into complex microfabricated devices is a process engineering research. It involves design of process flows and the choice of materials that are compatible with VACNF synthesis. This is a very challenging task. There is a lack of knowledge on how the nanostructure synthesis process affects the materials surrounding the nanostructure, how the post-synthesis processes are affected by now 3 D high-aspect ratio features, and what post-processing keeps the nanostructure functionality intact. This limited understanding prevents the development of real industrial applications. Vertically aligned carbon nanofibers have ideal properties for sensing, probing, and material delivery via their insertion into live cells. The goal of this work is to develop methods for the molecular-scale physical and informational interfacing between intracellular domains and synthetic nanostructures to study cellular functions. In this effort we investigate the processes of VACNF probe insertion, retention and electrical stimulation inside live cells, with the overarching goal of controlling and monitoring cell functions in massively parallel arrays. This effort will bridge a disciplinary gap between the physical and life sciences. Nanostructures are at the confluence of the smallest of human-made devices and the largest molecules of living systems. This confluence of sizes provides the basis for investigations into the interface of whole cell and synthetic systems at the molecular level.