Harmful algal bloom (HAB)-on-a-chip: Development of a microfluidic platform

to study algal chemotaxis

Kelly O’Quinn

Dr. Adam Melvin

Cain Department of Chemical Engineering

Louisiana State University

Harmful Algal Blooms

• Overabundance of algae– Karenia brevis

• Problems• Ecosystem• Economy• Health

• Reproduction and Migration

(1) http://oceanservice.noaa.gov/hazards/hab/(2) http://naturalunseenhazards.wordpress.com/2012/08/01/washington-warns-of-paralytic-shellfish-poison-biotoxin-found-in-

central-and-south-puget-sound-waters-lyme-disease-stories-presented-by-cdc-west-nile-virus-reports-from-ne-sc-tx-rabies-r/

Migration of Algae

•Phototaxis: upward migration toward light during day•Chemotaxis: downward migration toward nutrients at night

Heterogeneous Environments

• Algae migrate in response to many factors• Concentrations not constant throughout system

Developing a New Technology

• Microfluidic devices– Precise control of fluids– Laminar flow: diffusion-based mixing– Dynamic control

• Past research– Homogeneous tanks– Other microfluidic devices

http://www.rsc.org/ej/IB/2010/c0ib00055h/c0ib00055h-f1.gif

Design and Fabricate the Device

• Design in AutoCAD• Soft lithography

– Master• PDMS replication

Fabrication

Spin coat photoresist onto wafer

Cross-linked polymers stay and non cross-

linked dissolve in solution

Place photomask onto wafer then UV expose

then bake

Device Assembly

• Layers– PDMS– Agarose– Glass slide

• Tubes• Options for adhering layers

– Silanes– Thiol-ene resin– Plexiglas box– Negative pressure

Shing-Yi Cheng, Steven Heilman, Max Wasserman, Shivaun Archer, Michael L. Shuler and Mingming Wu, “A hydrogel-based microfluidic device for the studies of directed cell migration,” Lab Chip, 2007, 7, 763-769

Characterize the Device

• Ensure stable, well-controlled gradients formed• Fluorescent tracers• ImageJ line scan• COMSOL models

Implement the Device for Studying Algae Migration

• Chlamydomonas reinhardtii– Unicellular, survives in many environments

• Load both channels• Allow gradient to develop• Load cells into center, flow-free channel

Gathering and Analyzing Results

• Chemotactic Index– Vector assigning

• Design of Experiment (DOE)• Analysis of Variance (ANOVA)

Future Applications

• Better understanding of algae migration– Most prominent factors causing blooms

• Developing new technology– Future collaborations with other labs