A microfluidic device with integrated surface plasmon resonance (SPR) chemical and biological sensors based on arrays of nanoholes in gold films is demonstrated. Widespread use of SPR for surface analysis in laboratories has not translated to microfluidic analytical chip platforms, in part due to challenges associated with scaling down the optics and the surface area required for common reflection mode operation. The resonant enhancement of light transmission through subwavelength apertures in a metallic film suggests the use of nanohole arrays as miniaturized SPR-based sensing elements. The device presented here takes advantage of the unique properties of nanohole arrays: surface-based sensitivity; transmission mode operation; a relatively small footprint; and repeatability. Proof-of-concept measurements performed on-chip indicated a response to small changes in refractive index at the array surfaces. A sensitivity of 333 nm per refractive index unit was demonstrated with the integrated device. The device was also applied to detect spatial microfluidic concentration gradients and to monitor a biochemical affinity process involving the biotin-streptavidin system. Results indicate the efficacy of nanohole arrays as surface plasmon-based sensing elements in a microfluidic platform, adding unique surface-sensitive diagnostic capabilities to the existing suite of microfluidic-based analytical tools.
High-throughput platform targeting activity patterns of 3D neural cultures with arbitrary topology, by combining network-wide intracellular and local extracellular signals.
The sensitivity of biosensors is often not sufficient to detect diagnostically relevant biomarker concentrations. In this paper we have utilized a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) to detect dissipative losses induced by the attachment of intact vesicles. We modified a sandwich assay by coupling the secondary antibodies to vesi-cles. This resulted in an increase of detection sensitivity, achieving a diagnostically relevant detection limit of 5 ng/ml or 30 pM antigens. In addition, we could combine the individual assay steps to decrease the total time to result in about 30 minutes.
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