1) Single Wall Carbon Nanotubes (SWNTs): The metallic (met-) vs. semiconducting (sem-) nature of single wall carbon nanotubes (SWNTs) has attracted considerable attention from the scientific community. Our group was the first to report that using wet chemistry one can separate and/or enrich fractions of SWNTs according to type (or otherwise termed “metallicity”) and diameter. Aside from the immense technological importance of enhancing the structural purity and homogeneity of SWNTs, obtaining well-fractionated samples could also enable us to better characterize and model the effects of diameter and chirality. Our group is working to advance this separation methodology and obtain a better description of the physicochemical properties of solution-dispersed SWNTs. Separated SWNTs are poised to enhance considerably the properties of nanostructured devices. Building on our initial finding of self-assembled SWNT forest arrays, a number of enzymatic electrochemical biosensors have been developed in collaboration with Prof. Rusling’s group. More recently, we have been able to demonstrate SWNT forest-based electrochemical immunoassays with sensitivity exceeding that of traditional ELISA. Patterning of these SWNTs forest arrays at the nanometer level is currently used to produce nanosized needles that could electrochemically interface with living bacteria and cells, without disturbing their normal physciology (in collaboration with Professors Marcus, Rusling, Noll and Huey). 

2) Semiconductor Nanocrystals (NCs): Over the past ten years, our group has investigated two classes of semiconductor NCs: (a) Si-based quantum dots (QDs) for the fabrication of high refractive index (as high as 3.4) transparent nanocomposites, and (b) CdSe-based II-VI QDs and quantum rods for a number of optoelectronic and biomarker related applications. More recently, our group has been developing selective faceting methodologies for CdSe NCs, which are vitally needed in order to selectively control their interactions with a variety of biomolecules.

3) DNA-assisted solid freeform fabrication manufacture of photonic crystals: The ability of DNA oligomers to selective bind and recognize their complementary stands is currently used for the fabrication and immobilization of 2-dimensional photonic crystals of monodispersed colloidal microspheres. In collaboration with Prof. Marcus our groups have demonstrated selective insertion or defects at predetermined positions of these 2-D photonics crystals.

4) Totally implantable wireless glucose sensors: Real time monitoring of various metabolic analytes that control function and physiology of the human body is crucially needed for a variety of applications and especially for diabetic patients in everyday life. Our group, in collaboration with the groups of Professors Burgess and Jain, has been developing wireless, totally implantable glucosensors that exhibit significant size reduction, increased bio-acceptability and suppression of inflammation. Significant effort is exerted to identify the various failure mechanisms and improve upon both sin-vitro and in-vivo device stability.