RESUMEN
Dye molecules placed on metallic gratings can experience an enhanced electromagnetic field if illuminated under surface plasmon excitation conditions, a situation that can be employed for sensor applications. The fluorescence emission in this situation exhibits a characteristic emission polarization and geometry given by the fluorophore/grating interaction. We present experiments visualizing the full shape of the emission profiles and demonstrate how they can be manipulated by means of the grating constant. The excitation and emission processes taking place on the grating surface are characterized by polarization sensitive measurements.
RESUMEN
Clinical point of care testing often needs plasma instead of whole blood. As centrifugation is labor intensive and not always accessible, filtration is a more appropriate separation technique. The complexity of whole blood is such that there is still no commercially available filtration system capable of separating small sample volumes (10-100 µl) at the point of care. The microfluidics research in blood filtration is very active but to date nobody has validated a low cost device that simultaneously filtrates small samples of whole blood and reproducibly recovers clinically relevant biomarkers, and all this in a limited amount of time with undiluted raw samples. In this paper, we show first that plasma filtration from undiluted whole blood is feasible and reproducible in a low-cost microfluidic device. This novel microfluidic blood filtration element (BFE) extracts 12 µl of plasma from 100 µl of whole blood in less than 10 min. Then, we demonstrate that our device is valid for clinical studies by measuring the adsorption of interleukins through our system. This adsorption is reproducible for interleukins IL6, IL8, and IL10 but not for TNFα. Hence, our BFE is valid for clinical diagnostics with simple calibration prior to performing any measurement.