Surface Biopassivation of Replicated Poly(dimethylsiloxane) Microfluidic Channels and Application to Heterogeneous Immunoreaction with On-Chip Fluorescence Detection

Abstract

Poly(dimethylsiloxane) (PDMS) appeared recently as a material of choice for rapid and accurate replication of polymer-based microfluidic networks. However, due to its hydrophobicity, the surface strongly interacts with apolar analytes or species containing apolar domains, resulting in significant uncontrolled adsorption on channel walls. This contribution describes the application and characterization of a PDMS surface treatment that considerably decreases adsorption of low and high molecular mass substances to channel walls while maintaining a modest cathodic electroosmotic flow. Channels are modified with a three-layer biotin-neutravidin sandwich coating, made of biotinylated IgG, neutravidin, and biotinylated dextran. By replacing biotinylated dextran with any biotinylated reagent, the modified surface can be readily patterned with biochemical probes, such as antibodies. Combination of probe immobilization chemistry with low nonspecific binding enables affinity binding assays within channel networks. The example of an electrokinetic driven, heterogeneous immunoreaction for human IgG is described.

Mixing with bubbles: a practical technology for use with portable microfluidic devices

“…For PDMS devices a possible solution is to store them in hermetic, humidified containers. A choice of more hydrophilic polymer or use of passivated surfaces 48 (e.g. with proteins 49 ), or addition of surfactants to the solutions containing the analytes, may also solve this problem.…”

Polyelectrolyte Multilayers in Microfluidic Systems for Biological Applications

“…This problem is particularly challenging in instances when the analyte of interest is at a low concentration and is excessively lost due to non-specific binding in areas other than where the sensor is located. For polydimethylsiloxane (PDMS) microfluidic channels, rendering the PDMS surface hydrophilic reduces hydrophobic interactions of non-specific binding [16]. Typically, a blocking agent, such as bovine serum albumin (BSA) protein, is used to decrease non-specific binding in enzyme-linked immunosorbent assay (ELISA).…”

Surface modification in microchip electrophoresis

“…The main focus is on the improvement of electrophoretic separations by the reduction of analyte-wall interactions and the manipulation of electroosmosis. Approaches for surface derivatization of microfluidic chips in order to introduce additional functionality such as immunoassays [33][34][35][36], stationary phases for electrochromatography [37][38][39][40] and immobilized reagents [41] and enzymes [42,43] will not be discussed in detail.…”