Areas of interest

Biochemical engineering, biosensor, plant biotechnology, molecular biotechnology

Current research

We are interested in solving real-world problems using a combination of biological and engineering tools. Current research thrusts center on three main areas: plant molecular farming, sensor proteins, and magnetic separation.

Plant molecular farming: biotechnology and bioengineering

We have developed an innovative research program that integrates plant tissue culture, bioreactor engineering, and molecular biology to probe and enhance recombinant protein production by cultured plant cells and plants cultured in hydroponic systems. Using genetic fusion with the green fluorescent protein (GFP), we have been studying online real-time monitoring and dynamic optimization of recombinant protein expression in transgenic plant cell cultures. We have incorporated state-of-the-art optical sensing with advanced state-identification techniques to enable accurate real-time noninvasive sensing of culture GFP fluorescence. Research is also being done in our group to develop novel perfusion bioreactors for culture plant cells to high cell densities, and to develop general strategies suited for purifying GFP-tagged fusion proteins from cultured plant cells. We are also investigating novel molecular biology and metabolic strategies to increase recombinant protein production in plants and plant cell cultures. Furthermore, we have embarked on a study to produce more robust plant cells for mass culture, using metabolic engineering. In another research endeavor, we have been investigating coordinated expression of multiple proteins using polyprotein systems in an easily scalable hydroponic bioreactor.

Sensor proteins

Our overall interest in this area is to develop novel protein reagents to enable efficient homogeneous assays for fast, robust and accurate clinical and field detection of disease associated biomarker molecules and/or organisms. Based on our newly patented design concept (US patent# 7247443), we have created a series of synthetic fluorescent proteins through genetic and chemical manipulations that allow direct detection of target compounds in solution, in a rapid single-step “mix and test” assay process, using standard fluorometers. The modular nature of these FRET-based sensor protein design provides a molecular platform that can be conveniently modified for detecting different protein binding events. The fluorescent sensor technology is potentially suited for a broad range of applications in disease diagnosis and drug screening, as well as in basic research of protein-protein interactions. Our lab is currently working with BioXene, a Honolulu-based biotech firm, to pursue joint commercial development of the technology. This research was featured on the front page of Honolulu Advertiser on Nov. 10, 2005 (see link: In addition to the FRET-based sensor proteins, we are currently working on other fluorescent- and non-fluorescent-based recombinnat sensor proteins. A postdoc position is currently available to study the development of phage-mediated signal-amplification system for immunoassays and novel hybrid sensor proteins for proximity-ligation assays.

Magnetic cell separation

As a part of a USDA-NRI supported project to develop an integrated strategy for efficient detection of plant pathogens, we are currently investigating the use of magnetic separation to process a continuous flow of liquid samples for concentrating potential pathogenic targets. While magnetically stabilized fluidized beds (MSFB) have been used in the past, we have developed an innovative magnetic separator that provides enhanced mass transfer without compromising the magnetic stabilization property, when compared with the conventional MSFB system. Inexpensive micron-sized magnetic beads are fabricated and used to capture target organisms, which are then conveniently detected in-situ using a highly sensitive immuno-detection technique with minimum sample processing. Computer simulations of the novel magnetic separator using Femlab provide a basis for further optimization of the system. A postdoc position is currently available to study the hydrodynamics and mass transfer in the novel magnetic separator.


BE 360 Mass and Energy Balances

BE 460 Bioreactor Design and Analysis

BE 660 Bioseparation Processes

MBBE 610 Molecular Biosciences Seminar


Su, W.W. 2007. Sensor constructs and detection methods. US patent 7247443, issued on July 24, 2007.

Chang, S., Christopher, D., Vine, B., Su, W.W., Bugos, R. 2006. Plasmodium falciparum merozoite surface protein-1 malaria vaccine produced in transgenic plants.  US Patent 7037681, issued May 2, 2006.

Su, W.W. 1994. External-loop perfusion air-lift bioreactor. US Patent 5342781, issued on August 30, 1994.

Selected Publications

Vardar-Schara, G., Krab, I.M., Yi, G., Su, W.W. 2007. A homogeneous fluorometric assay platform based on novel synthetic proteins. Biochem. Biophys. Res. Commun. 361, 102-108.

Peckham, G. D., Bugos, R.C., Su, W.W. 2006. Purification of GFP fusion proteins from transgenic plant cell cultures. Protein Expr. Purif. 49, 183-189.

Su, W.W. 2006. Bioreactor engineering for recombinant protein production using plant cell suspension culture. In: Dutta Gupta, S. and Ibaraki, Y. (eds.) Plant Tissue Culture Engineering. Springer, Berlin; pp. 135-159.

Su, W.W. and Lee, K.T. 2006. Plant cell and hairy-root cultures – process characteristics, products, and applications. In: Yang, S.T. (ed.) Bioprocessing for Value-Added Products from Renewable Resources: New Technologies and Applications, Elsevier, New York; pp. 263-292. 

Su, W.W., Liu, B., Lu, W.B., Xu, N.S., Du, G.C., Tan, J.L. 2005. Observer-based online compensation of inner filter effect in monitoring fluorescence of GFP-expressing plant cell cultures. Biotechnol. Bioeng. 91(2), 213-226.

Su, W.W. 2005. Fluorescent proteins as tools to aid protein production. Microbial Cell Factories 4, 12.

Wang, M.L., Goldstein, C., Su, W.W., Moore, P.H., Albert, H.H. 2005. Production of biologically active GM-CSF in sugarcane: a secure biofactory. Transgenic Research 14, 167-178.

Parambam, R.I., Bugos, R., Su, W.W. 2004. Engineering green fluorescent protein as a dual functional tag. Biotechnol. Bioeng. 86(6), 687-97.

Su, W.W., Guan, P.Z., Bugos, R. 2004. High level of secretion of functional green fluorescent protein from transgenic tobacco cell cultures: characterization and sensing. Biotechnol. Bioeng. 85(6), 610-9.

Su, W.W., Li, J., Xu, N.S. 2003. State and parameter estimation of microalgal photobioreactor cultures based on local irradiance measurement. J. Biotechnol. 105(1,2), 165-178.

Su, W.W., Arias, R. 2003. Continuous plant cell perfusion culture: bioreactor characterization and secreted enzyme production. J. Biosci. Bioeng. 95 (1), 13-20.

Li, J., Xu, N.S., Su, W.W. 2003. Online estimation of stirred-tank microalgal photobioreactor cultures based on dissolved oxygen measurement. Biochem. Eng. J. 14 (1), 51-65.

Zhang, J.N., Su, W.W. 2002. Estimation of intracellular phosphate content in plant cell cultures using extended Kalman filter. Journal of Bioscience & Bioengineering. 94 (1), 8-14.

Liu, S., Bugos, R., Dharmasiri, N., Su, W.W. 2001. Green fluorescent protein as a secretory reporter and a tool for process optimization in transgenic plant cell cultures. J. Biotechnol. 87 (1), 1-16.

Shi, H.D., Su, W.W. 2001. Display of green fluorescent protein on the Escherichia coli cell surface. Enzyme & Microbial Technol. 28, 25-34.

Su, W.W. 2000. Perfusion bioreactors. In: Spier, R.E. (ed.) Encyclopedia of Cell Technology, Vol. 1, Wiley New York. pp. 230-242.