Benjamin G. Hawkins

 While often studied in planktonic state, many bacterial species live predominantly in biofilms: surface-associated colonies surrounded by an extracellular polymeric substance (EPS) composed of excreted polysaccharides, lipids, DNA, and proteins. Biofilms provide a degree of protection from mechanical and chemical stressors for incorporated cells, and are often quite difficult to remove. While individual cells are no more resistant to antimicrobial treatment, the presence of dormant, "persister" cells makes biofilm colonies significantly difficult to eliminate. While not always harmful (e.g., dental plaque), biofilm associated bacteria can negatively impact a wide range of industries, contributing to premature fouling and corrosion of industrial equipment and product contamination. In the healthcare industry, biofilms are responsible for a large portion of implant related and nosocomial infections (e.g., catheters, pacemakers), as well as several disease states, such as pneumonia cause by Pseudomonas aeruginosa infections and Legionnaire's diseased caused by Legionnella infection.

The discovery that biofilms contribute significantly to bacterial phenotype in both ecological and in vivo environments has spurred significant research interest. Studies investigating composition, synthesis, and mechanical properties have rapidly expanded our knowledge of biofilms, but significant work remains to be done. Model systems for biofilm growth, in particular, either poorly mimic the biofilm environment or suffer experimental challenges such as low throughput and labor intensive protocols.

We are currently working to develop a high-throughput microfluidic platform to culture highly reproducible P. aeruginosa biofilm populations based on existing standard culture techniques. Highly reproducible biofilm samples allow for quantitative comparison of results across researchers and laboratories. Microfluidic devices offer a number of advantages over traditional culture techniques, such as exquisite control over local mechanical and chemical microenvironments, high-throughput capabilities, and the potential for automated operation. In addition to reproducible biofilm samples, we are currently studying the effects of the fluid shear environment on three-dimensional biofilm morphology and developing new metrics for quantification of biofilm growth.

Publications

Hawkins BG, Huang C, Arasanipalai S, Kirby BJ 
"Automated dielectrophoretic chracterization of Mycobacterium smegmatis," Analytical Chemistry, 2011. http://dx.doi.org/10.1021/ac2002017

Pratt ED, Huang C, Hawkins BG, Gleghorn JP, Kirby BJ 
"Rare cell capture in microfluidic devices," Chemical Engineering Science, Vol 66(7)1508-1522, 2011. http://dx.doi.org/10.1016/j.ces.2010.09.012

Hawkins BG, Kirby BJ 
"Electrothermal flow effects in insulating (electrodeless) dielectrophoresis systems," Electrophoresis, 31:3622-3633, 2010. http://dx.doi.org/10.1002/elps.201000429

Hawkins BG, Gleghorn JP, Kirby BJ
"Dielectrophoresis for Particle and Cell Manipulations", Methods in Bioengineering: Biomicrofabrication and Biomicrofluidics, Zahn J (ed.), Artech House, Boston, 2009.

George PA, Hui W, Rana F, Hawkins BG, Smith AE, Kirby BJ 
"Integrated microfluidic devices for terahertz spectroscopy of biomolecules", Optics Express, 16(3) 1577-1582 (2008). http://dx.doi.org/10.1364/OE.16.001577

Hawkins BG, Smith AE, Syed YA, Kirby BJ 
"Continuous-flow particle separation by 3D insulative dielectrophoresis using coherently shaped, DC-biased, AC electric fields," Analytical Chemistry, 2007. http://dx.doi.org/10.1021/ac0707277