Recent Projects in Integrative Nanosciences

DNA microarrays, nanowires and nanoparticles

recent work by Dr. Jingjiao Guan

Fluorescence image of an array of stretched DNA: Genome DNA can be uncoiled, stretched, and immobilized into a large, well-defined array on a surface containing microwells through a simple dewetting process. This technique holds potential to develop a new DNA microarray technology for genetic analysis and medical diagnosis at the level of single DNAs and cells.

Fluorescence image of an array of stretched DNA (green) nanowires with nanocrystal quantum dots incorporated (yellow): Nanowires are potential building blocks for next-generation computer chips and ultrasensitive sensors. By using stretched DNA as templates, a large, well-defined array of suspended, functionalized nanowires can be generated on micropillars. The nanowire array promises to build large-scale, multiplex nanowire sensors for a wide variety of applications such as biomedical sensing and environmental monitoring and homeland security.

Scanning Electron Microscopy image of a hybrid array of gold-coated DNA nanowires and salt nanoparticles: Like nanowires, nanoparticles are cornerstones of nanotechnology. A hybrid array containing both nanowires and nanoparticles with precisely controlled size, location, and orientation can be generated by a single-step dewetting process. The method holds potential to build novel nanodevices integrating unique properties and functionalities of nanowires and nanoparticles.

Publications:

Jingjiao Guan, L. James Lee, Generating Highly Ordered DNA Nanostrand Array, Proceedings of National Academy of Science, U. S. A. (2005) 102: 18321-18325.

Jingjiao Guan, Bo Yu, L. James Lee, Forming Highly Ordered Arrays of Functionalized Polymer Nanowires by Dewetting on Micropillars, Advanced Materials (2007) 19: 1212-1217.

Jingjiao Guan, Nick Ferrell, Bo Yu, Derek Hansford, L. James Lee, Simultaneous Generation of Hybrid Arrays of Micro/Nanoparticles and Nanowires by Dewetting on Micropillars, Soft Matter (2007) 2: 1369-1371.

Magnetic detection of biotin-streptavidin binding using InAs quantum well µ-Hall sensor

recent work by Khaled Adealat & Kansheng Chen

Upper image: SEM image of two self assembled ~250nm superparamagnetic beads over an InAs quantum well Hall sensor via biotin-streptavidin interaction. Dip-pen technique was used to selectively functionalize the active areas of the sensor and the rest areas were passivated to minimize nonspecific binding.

Lower image: The drop in the Hall voltage signal for the occupied cross (red line) compared to the unaltered signal of the empty cross (green line) when an external magnetic filed is applied indicates the presence of the magnetic beads. The signal to noise ratio is 8.3. This indicates the capability of this sensor to detect a single bead with equal (~250nm in diameter) or even smaller size.

InAs quantum well Hall devices are promising room-temperature sensors for magnetic biomolecular labels which can be utilized for wide ranging applications in biology and medicine. [G. Mihajlovic et al., APL 87, 112502 (2005)]