Single molecule imaging of NGF axonal transport in DRG neurons
Manipulating the axonal transport process by magnetic and optical trapping
Nanopillar optics for cell imaging
Nanopillar probes for cell physiology
Single molecule biophysics for neurobiology
Single molecule measurements show great potential for characterizing complex dynamic behavior: such measurements allow one to look beyond the ensemble average and measure real-time trajectories of individual molecules to determine the exact distributions of molecular properties. In the light of new technique advances, single molecule fluorescence imaging studies have been carried out in live cells and provide a direct way to quantify biological events inside cells with a high spatial and temporal resolution.
We are interested in developing and applying single molecule fluorescence imaging method to visualize signal flow in neurons. The biological question of interest is the molecular mechanisms associated with neurotrophin signaling and the implications of those mechanisms for neurodegenerative diseases. Methods of interest include pseudo total-internal-reflection-fluorescence (TIRF) microscopy, fluorescence-resonance-energy transfer (FRET) nanometer localization of a single fluorophore, and using quantum dots as a novel fluorescent label. Standard biochemical and molecular biology methods (cloning of genes, expression of recombinant proteins in bacteria, and transfection of plasmids into mammalian cells etc.), are used to exam cellular events associated with neurotrophin signaling.
Manipulating the axonal transport process by physical forces
The extreme lengths and narrow calibers of axons, along with the large amount of materials that must be transported through axons represent unique challenges for neurons. Defective axonal transport, such as accumulation of axonal cargoes and slower transport rate, has been linked with a range of neurodegenerative diseases. When perturbing the axonal transport process using genetic, biochemical or pharmacological methods, many other cellular processes are simultaneously affected, thus making it difficult to pinpoint the role of “ transport defect ” in the process of neuronal degeneration.
We are interested in developing a novel technique that permits external manipulation of axonal transport via magnetic forces. By using soft magnetic materials that can be magnetized or de-magnetized by remotely placed macroscopic magnets, we have control over the location, timing and the degree of the induced-traffic jams. This capability to precisely manipulate axonal transport addes new dimension to the imaging technique to observe axonal transport dynamics in real time.
vertical nanopillar for optical imaging
We are using vertical nanofiber as a near-field optical illumination method to study the biological events inside mammalian cells or at cell membrane. Observing individual molecules in a complex environment by fluorescence microscopy is becoming increasingly important in biological and medical research, for which critical reduction of observation volume is required. We developed a novel method to critically reduce the excitation volume by using vertically aligned silicon dioxide nanopillars. We are interested in using this technique to study how proteins are transported in and out of cells or neucleus.
nanopillar electrode Arrays for electrophysiology
We found that live cells form tight junctions with nanopillar structures. Taking advantage of this observation, we are developing nanometer sized nanopillar-electrode for highly sensitive detection of electric activities of the interfacing cells.