October 10, 2013

Speaker: Jesse Greener, Laval University

Title: Microfluidics and Spectral Imaging for the Study of Flow-Templated Biomaterials

Abstract: Microfluidic (MF) technology is finding new opportunities in biomaterial synthesises due to exceptional control of reaction variables, control over mixing, reduction of material consumption, and isolation of the growth environment from ambient conditions. The use of MFs for studies of biomaterials is very attractive due to the ability to precisely control the wall shear stress, temperature and chemical gradients. Generally, in situ imaging of biofilms and other biomaterials is accomplished by 2D or confocal microscopy techniques. However, the rapid pace of MF-based material development has placed strong demands on in situ characterization. To this end, there has been an increasing push for new spectral imaging methods that can simultaneously report on a broad range of chemical properties without the need of additional foreign probe molecules. In this talk, a microfluidic bioreactor with an easy to fabricate nano-plasmonic surface is demonstrated for studies of biofilms and their precursor materials via surface enhanced Raman spectroscopy (SERS). The system uses a novel design to induce sheath flow confinement of a sodium citrate biofilm precursor stream against the SERS imaging surface to measure spatial variations in the concentration profile. The unoptimised SERS enhancement was approximately 2.5 x 104, thereby improving data acquisition time, enabling reduced laser power requirements and enabling a citrate detection limit of 0.1mM, well below the concentrations used in biofilm nutrient solutions. The flow confinement was observed by both optical microscopy and SERS imaging with good complementarity. We demonstrate the new bioreactor by growing flow-templated biofilms on the microchannel wall. This work opens the way for in situ spectral imaging of biofilms and their biochemical environment under dynamic flow conditions.