Determination of Affinity and Kinetic Constants of the Biotin-Streptavidin Complex Using Microfluidic GMR Biosensors

Studies of the interactions between biological molecules are of highest importance in a vast number of areas of biomedicine and biotechnology. Herein, we present a microfluidic platform based on giant magnetoresistive (GMR) biosensor to study the affinity and kinetic constants of biological molecules. The GMR biochip combined with microfluidic system has high reaction efficiency. The GMR microfluidic biosensor has been successfully used to perform online kinetic measurements of biotin and streptavidin. The affinity and dissociation reaction rate constants are consistent with literature results. Furthermore, we studied the adsorption process of three different types of superparamagnetic nanoparticles with sizes ranging from 50 to 500 nm on the biosensor. Different adsorption models were used to fit the curves. This paper provides a useful guidance in detecting the thermodynamic and kinetic parameters of receptors-ligands, enzymes-substrates, and drug molecules, as well as in diagnosing some diseases.