Major Recognitions and Honors
Significant Professional Service and Activities
Materials, Bio-Nanoscience, Electrochemistry
My expertise in nanomaterials synthesis and electrochemistry forms the foundation of my research program. We are in general interested in the synthesis of 1-D nanotubular and nanowire structures with various materials since the 1-D structure has many attributes that other nanostructures do not have. With the fundamental study on the nanotubes, very importantly, we are also interested in application of these various 1-D naostructures at biomedical, materials, and energy fields.
Research projects may be categorized into three major areas: (1) synthesis and characterization of nanotube structures with various electronic and/or electrochemical materials and their application to ultrafast electrochromic display and high-power energy storage devices, (2) synthesis and characterization of bio-nanotubes for biomedical applications such as targeted drug delivery and biosensors, and (3) investigation of fundamental physical and chemical properties of nanostructured materials such as diffusion and reaction problems in a confined geometry of silica nanotube.
Synthesis and application of nanotube structure with electrochemical materials
We are investigating new electrochemical growth mechanisms of the conductive polymer nanotubes and metal nanotubes in cylindrical pores of a template. Using poly(ethylenedioxythiophene) (PEDOT) nanotubes, we have demonstrated the world-first moving-image speed in the electrochromic device with high optical color contrast, which has never been achieved simultaneously before. Nanotube structure enables us to design extremely fast charge transport devices due to thin nature of nanotube wall and well-aligned array structure. This discovery makes mass production possible in the fabrication of well-defined nanotubes with various materials from metals to metal oxides to polymers and opens a numerous applications of nanotubes to electrochemical devices. Using the same principle, we are developing high-power high-energy storage devices such as supercapacitors and highpower batteries that will also enable fast charge for high energy electric devices. Substantially improved metrics such as power and energy density per unit volume or weight govern viability and adoption of major solutions, such as the plug-in electric car. Alternative energy sources (solar, wind, etc.) with variable delivery rates underscore an increasingly important need to store the captured energy for power delivery on demand, where temporal profiles of capture and delivery-on-demand are uncorrelated.
Synthesis and characterization of bio-nanotubes for biomedical applications
As an ideal platform for targeted drug delivery, nano-scale drug carrier should have multifunctionality and many other attributes, such as targeting moiety, drug uptake and releasing control, imaging capability, proper small size and size distribution, and non-toxicity. We are opening a new area in the nanomaterial field for the drug delivery through the synthesis of magnetic nanotubes by combining the attractive tubular structure with magnetic property. Nanotubes have several advantages as advanced drug carriers. First their inner voids can be used to load large amounts of drug molecules. Their open ends can be used as a gate to control drug release. Secondly differential functionalization can allow selective attachment of moieties to the inside (such as drugs, radionuclides) and outside (targeting moieties). Thirdly they are mechanically robust with no swelling or porosity changes under physiological conditions. Finally, by loading drugs inside the tubes, the outer surface can be kept biocompatible which can prevent aggregation and non-specific adsorption as commonly seen with nanoparticles where hydrophobic drugs are attached to the surface. The drug molecules can also be protected from any unwanted biological reaction such as enzymatic DNA/RNA cleavages. The magnetic nanotube can be an ideal candidate for the platform of multifunctional image-guided targeted drug delivery since the magnetic property can be used for tracing the materials with magnetic resonance imaging (MRI) technology and also used for the control of carrier delivery with magnetic field.
We are synthesizing barcoded silica nanotubes with segments of different diameters that can act as ‘coded labels’ for identifying and tracking biomaterials such as proteins and cells. These shape-coded nanotubes can be used as markers for multiplex biosensing. We are also synthesizing successfully barcoded magnetic nanotubes (BMNTs) for separation and detection of bioanalytes and combining the magnetic barcoded nanotubes with microfluidic channels for the automation of separation and detection.
Diffusion and reaction problems in a confined geometry of silica nanotube
To investigate basic questions surrounding nanofluidics (wetting and dewetting), catalytic reactions and molecular diffusion in a confined nanoscale geometry. We are investigating; (1) Wetting and diffusion problem in a silica ), (2) Catalytic reactions in a catalyst-anchored silica nanotube (J. Am. Chem. Soc., 2008), (3) Control of atomic layer deposition in nanoscale cylindrical pores (Small, 2008)