title: Microfluidic, bead-based assay: Theory and experiments.
abstract: Microbeads are frequently used as a solid support for biomolecules such as proteins and nucleic acids in heterogeneous microfluidic assays. However, relatively few studies investigate the binding kinetics on modified bead surfaces in a microfluidics context. In this study, a customized hot embossing technique is used to stamp microwells in a thin plastic substrate where streptavidin-coated agarose beads are selectively placed and subsequently immobilized within a conduit. Biotinylated quantum dots are used as a label to monitor target analyte binding to the bead's surface. Three-dimensional finite element simulations are carried out to model the binding kinetics on the bead's surface. The model accounts for surface exclusion effects resulting from a single quantum dot occluding multiple receptor sites. The theoretical predictions are compared and favorably agree with experimental observations. The theoretical simulations provide a useful tool to predict how varying parameters affect microbead reaction kinetics and sensor performance. This study enhances our understanding of bead-based microfluidic assays and provides a design tool for developers of point-of-care, lab-on-chip devices for medical diagnosis, food and water quality inspection, and environmental monitoring.
authors.affiliation: Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, 19104, USA.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Thompson
authors.forename: Haim H
authors.initials: HH
authors.lastname: Bau
mesh_terms: D003198:Computer Simulation; D020342:Finite Element Analysis; D055767:Immobilized Proteins / Q000737:chemistry; D007163:Immunosorbent Techniques / Q000295:instrumentation*; D007700:Kinetics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D008863:Microspheres; D008956:Models, Chemical; D011485:Protein Binding; D012685:Sepharose; D013050:Spectrometry, Fluorescence
chemical_list: D055767:Immobilized Proteins; D012685:Sepharose