In spintronics, Dr. Punnoose's group is doping known semiconductors such as TiO2, SnO2 and ZnO with transition metals to introduce ferromagnetism, motivated by several recent theoretical predictions. Devices employing ferromagnetic semiconductors might allow the integration of data processing and magnetic storage on a single chip, leading to further miniaturization of devices and increased processing speed. Ferromagnetism has been reported in several different oxide semiconductor systems and the group is collaboration with Dr. J. S. Moodera’s group at Massachusetts Institute of Technology to develop spintronic devices. These materials are also attractive for photonic applications.

The foundation of nanotechnology research is based on the ability of synthetic methods to modify the electrical, magnetic, optical, structural, morphological and chemical properties of materials and structures with dimensions of roughly 1–100 nm by controlling their size, shape and surface area. Within this size range unique phenomena and novel physical, chemical and biological properties of materials, different from their bulk counterparts, enable innovative applications. Dr. Punnoose’s group is involved in the sized controlled synthesis of nanomaterials, their detailed characterization and investigation of size dependent changes in the properties of these materials.

The nanoparticle size, being comparable to the size range of biological molecules and structures, make them very attractive materials for manipulation, sensing and detection of biological structures and systems, leading to the development of nanobiotechnology. The impact of nanotechnology is predicted to far exceed that of the industrial revolution and the projected revenue for industrial, biological and medical applications of nanotechnology is predicted to become a $1 trillion market by 2015. Dr. Punnoose and his collaborators are making efforts to use nanostructured materials in biomedical applications, therapeutics, cancer treatments, cell imaging, nano-bio-sensors and antibacterial treatment.

New progress in science never comes without challenges and the nano-bio research is no exception. Dr. Punnoose and his collaborators have recently shown that low concentrations of nanoscale oxides such as ZnO can kill certain types of bacteria and human cells while their bulk counterparts are non-toxic. More challenging is the fact that the cytotoxic response is very different between different cell types and nanomaterial systems, making it difficult to develop predictive models. A fundamental understanding of the factors controlling the internalization mechanism, cellular uptake, and cytotoxicity has not yet been achieved. Dr. Punnoose along with half a dozen collaborators care currently investigating the cytotoxicity of various nanomaterials to different eukaryotic and prokaryotic cell types.

In addition, the group is also investigating various types of magnetic nanoparticles. Nanoscale ferromagnetic particles exhibit several unique properties including superparamagnetism, an important phenomena with serious consequences in magnetic recording industry. Antiferromagnetic(AF) materials received an increased interest in the recent past due to their use in exchange anisotropy based spin-valves and other devices involving AF pinning layers. Magnetic nanoparticles also being investigated for novel drug delivery applications.

In the area of nanocatalysis, Dr. Punnoose is investigating a variety of nanocatalysts used in Fischer-Tropsch chemistry. Nanomaterial support allow more efficient distribution of the catalytic species. Primary focus in this area is to investigate the catalytic mechanism at the nanoscale.

Dr. Punnoose’s group has developed a novel gas/chemical sensor using unique properties of nanoscale magnetic semiconductor oxide materials. Unlike the existing gas/chemical sensors which use change in the electrical or optical properties, these nanosensors utilize changes in the magnetic properties of nanoparticles in presence of gases and chemical species.