High Througput Enzyme Kinetics Using a Custom Built Microfluidic Benchtop System

Prior to attending graduate school, I worked with a dynamic group of biologists and engineers at GlaxoSmithKline in RTP, NC on a microfluidic instrument for high throughput enzyme kinetics. As part of the Technology Development Department, we built an automated instrument based around a microfluidic chip (Fig 3A). The chip was coupled to an automated sample injector, such that samples from a plate could be serially injected into the chip. Samples from a library of drug compounds were serially injected into the chip and mixed continuously with an enzymatic system of interest. Using specially made positive displacement servo-based syringe pumps, the drug compounds were precisely mixed with the enzyme and substrate in continuously varying amounts. A fluorescent reaction was coupled, so the enzymatic activity could be quantitatively recorded. The instrument was fully controlled by a custom built LabVIEW program, including up to 5 syringe pumps, thermal control of the syringe pumps to keep the enzymes at 4C for extended life, thermal control of the microfluidic chip, an autosampling robot to obtain drug compounds and inject them into the chip, shutters and mirrors to switch between different excitation lasers and filters, control of motorized microscope stage to scan different parts of the chip, motorized control of microscope focus, as well as data acquisition from thermal probes, photodetectors, and position of syringe pump. The end result was an instrument used internally at GSK, and the intellectual property of the instrument was recently purchased by Eksigent. A prototype is shown in the figure below.

The following figure shows some of the chips used. We developed a novel way to make fluidic interconnects to the chips that have virtually zero wasted volume. Of note, we made thousands of these interconnects with great success using an automated method.

We are currently in the process of publishing much of the work from this project, and have numerous papers under revision. As soon as they are published, I will post them here, as well as some more images.

References:

1. DM Hartmann*, JT Nevill*, KI Pettigrew, G Votaw, PJ Kung, and HC Crenshaw,” A Low-Cost, Manufacturable Method for Fabricating Capillary and Optical Fiber Interconnects for Microfluidic Devices,” Lab Chip, 2008. (DOI:10.1039/B716994A) *contributed equally
2. DM Hartmann, D Wyrick, JT Nevill, G Votaw, JS Chen, and HC Crenshaw, "Rational Design of Expansion Channels for Low-Pass Filtering of Concentration Gradients in Microfluidic Systems," Lab Chip, 2008. (under review)
3. Microfluidic apparatus and method for sample preparation and analysis (PCT/US2006/031161)
4. Apparatus and method for handling fluids at nano-scale rates (PCT/US2006/031166)
5. Microfluidic based apparatus and method for thermal regulation and noise reduction (PCT/US2006/031160)
6. Microfluidic systems and methods for reducing diffusion and compliance effects at a fluid mixing region (PCT/US2006/031053)
7. Microfluidic systems and methods for reducing noise generated by mechanical instabilities (PCT/US2006/031054)
8. Microfluidic systems and methods for reducing background auto fluorescence and the effects thereof (PCT/US2006/031158)
9. Microfluidic chips having fluidic and optical fiber interconnections and related methods (PCT/US2006/031164)