Abstract
BackgroundThe interest in microfluidics and surface patterning is increasing as the use of these technologies in diverse biomedical applications is substantiated. Controlled molecular and cellular surface patterning is a costly and time-consuming process. Methods for keeping multiple separate experimental conditions on a patterned area are, therefore, needed to amplify the amount of biological information that can be retrieved from a patterned surface area. We describe, in three examples of biomedical applications, how this can be achieved in an open microfluidic system, by hydrodynamically guiding sample fluid over biological molecules and living cells immobilized on a surface.ResultsA microfluidic format of a standard assay for cell-membrane integrity showed a fast and dose-dependent toxicity of saponin on mammalian cells. A model of the interactions of human mononuclear leukocytes and endothelial cells was established. By contrast to static adhesion assays, cell-cell adhesion in this dynamic model depended on cytokine-mediated activation of both endothelial and blood cells. The microfluidic system allowed the use of unprocessed blood as sample material, and a specific and fast immunoassay for measuring the concentration of C-reactive protein in whole blood was demonstrated.ConclusionThe use of hydrodynamic guiding made multiple and dynamic experimental conditions on a small surface area possible. The ability to change the direction of flow and produce two-dimensional grids can increase the number of reactions per surface area even further. The described microfluidic system is widely applicable, and can take advantage of surfaces produced by current and future techniques for patterning in the micro- and nanometer scale.
Highlights
The interest in microfluidics and surface patterning is increasing as the use of these technologies in diverse biomedical applications is substantiated
Variation within and between lanes produced by hydrodynamic guiding Fluorescein-labeled biotin was guided sequentially in ten lanes over immobilized streptavidin
In order to study the variation within and between lanes produced by hydrodynamic guiding, a two-dimensional grid was made by guiding fluorophore-labeled biotin over immobilized streptavidin in two dimensions sequentially
Summary
The interest in microfluidics and surface patterning is increasing as the use of these technologies in diverse biomedical applications is substantiated. In three examples of biomedical applications, how this can be achieved in an open microfluidic system, by hydrodynamically guiding sample fluid over biological molecules and living cells immobilized on a surface. Microfluidic technology holds promise for advances in analytical biochemistry, drug discovery and development, and cellular and tissue research and engineering. The fluid dynamics, the large ratio of surface area to volume, and the significant surface tension forces of microfluidic systems can be exploited to achieve fast and sensitive bioanalysis [1,3]. Microfluidics is useful for patterning of cells in tissue architectures, and for local delivery of chemical agents [5]. Microfluidic-based assays should, be better suited than the classical static assay systems for studying endothelial cells and their interactions with blood cells, cancer cells and circulating stem and progenitor cells
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