In this lecture, we look at the mass transfer coefficient of association and dissociation rates of molecules on the biosensor and off of it. Having a flow cell speeds it up, but the molecules must get through a stagnant layer to get to the biosensor. The rate of binding of biomolecules to a sensor can be determined by the flow rate; Analyte,Ligand, dissociation coefficient, association coefficient, concentration of analyte in solution; and the rate of diffusion. However, it is limited by mass transport and chemical reaction. We want to measure the effects of the things listed in the previous sentence on the chemical reaction, but must make sure not to mistake it for mass transport, which is diffusion. You can do this by measuring the association and dissociation coefficients rates under different flow rates. If the flow rate does not change, then it is not limited by mass transport and the sensor response is then limited by the chemical reaction.
My research group is focused on the application of sub-wavelength optical phenomena and fabrication methods to the development of novel devices and instrumentation for the life sciences. The group is highly interdisciplinary, with expertise in the areas of microfabrication, nanotechnology, computer simulation, instrumentation, molecular biology, and cell biology. In particular, we are working on biosensors based upon photonic crystal concepts that can either be built from low-cost flexible plastic materials, or integrated with semiconductor-based active devices, such as light sources and photodetectors, for high performance integrated detection systems.
Using a combination of micrometer-scale and nanometer-scale fabrication tools, we are devising novel methods and materials for producing electro-optic devices with nanometer-scale features that can be scaled for low-cost manufacturing. Many of our techniques are geared for compatibility with flexible plastic materials, leading to applications such as low cost disposable sensors, wearable sensors, flexible electronics, and flexible displays. Because our structures manipulate light at a scale that is smaller than an optical wavelength, we rely on computer simulation tools such as Rigorous Coupled Wave Analysis (RCWA) and Finite Difference Time Doman (FDTD) to model, design, and understand optical phenomena within photonic crystals and related devices.
In addition to fabricating devices, our group is also focused on the design, prototyping, and testing of biosensor instrumentation for high sensitivity, portability, and resolution. Advanced instruments enable high resolution imaging of biochemical and cellular interactions with the ability to monitor images of biochemical interactions as a function of time. Using the sensors and instrumentation, we are exploring new applications for optical biosensor technology including protein microarrays, biosensor/mass spectrometry systems, and microfluidics-based assays using nanoliter quantities of reagents. The methods and systems developed in the laboratory are applied in the fields of life science research, drug discovery, diagnostic testing, and environmental monitoring. -From Professor Cunningham's Faculty Profile
University of Illinois at Urbana-Champaign, Urbana, IL