Bioanalytical Chemistry and Physical Chemistry

The research work conducted in my group at Simon Fraser University spans a broad range of analytical, physical, and materials chemistry. In particular, we are interested in surface modification with self-assembled monolayers, fabrication/characterization of nanostructured materials, and development of biosensing devices. Active projects include:

DNA Modified Surfaces: Design, Fabrication, and Diagnosis

DNA chips are important in contemporary research because of their ability to obtain information on nucleic acid sequence and manipulation faster, simpler, and less expensively compared to traditional methods. In addition, DNA-based biosensors provide almost limitless capability of detecting molecular analytes, from small to large, from chemical to biological. These hybrid devices require improvements in their fabrication and characterization by physical scientists and engineers; our research contributes in several different ways including the preparation and attachment of DNA probes, the characterization of the chip surfaces, and the assessment of sensing mechanisms. Experimental techniques involve DNA manipulation, molecular self-assembly, electrochemistry, scanning probe microscopy, infrared spectroscopy, solid-state electrical measurements, as well as other surface evaluations.

Analytical Chemistry on Recordable CDs

Our early invention of recordable compact disks (CD-Rs) as a source for gold substrates was featured in Photonics Spectra (December 2001) and Canadian Chemical News (February 2002). In particular, we have established an easy, inexpensive, and reproducible method to prepare self-assembled monolayers (SAMs) on CD-R gold substrates after removing the protective polymer films with concentrated nitric acid. As an extension, we demonstrated that CD-R gold films are ideal as micro-patterned conductive substrates for the "customized" fabrication of material microstructures. Currently we are working on the immobilization of biological macromolecules on CD-R substrates, and exploring the possibility to use CD-R writing and reading technology for surface modulation and detection.

Molecular Modification of Classical Microelectronic Devices

We have explored the use of organic monolayers on crystalline silicon to change the interfacial nature of metal-semiconductor junctions. It has been shown that Si-C bonded alkyl monolayers can effectively passivate silicon surfaces and molecularly tune the effective barrier heights of thus formed diode junctions. Organic modified and native oxide passivated silicon substrates were compared to explore the possibility of using molecular materials as ultrathin insulating layers for microelectronics. To search for low (or non-) leakage molecular diodes, we are currently experimenting with different methods for preparing the mental contacts, with varied functional molecules, and with nanoscale characterization tools (e.g., current-sensing Atomic Force Microscopy, Ballistic Electron Emission Microscopy).

Collaborative Research

We have been actively collaborating with a number of SFU colleagues; for example, we are working on the development of DNA-based biosensors for cancer markers with Dr. Sen's laboratory in the Department of Molecular Biology and Biochemistry, on the preparation/characterization of molecular contacts with Dr. Bechhoefer and Dr. Karen Kavanagh in Physics, and on the fabrication of point-of-care diagnostic devices with Dr. Ash Parameswaran in the School of Engineering Science. We also have connections with research groups in the USA, Japan, and China for long term collaborations. Opportunities are available for students to work in famous international laboratories and to experience the diverse culture, society, and people.