A Centrifugal Microfluidic Platform for Biomarker Detection in Blood using BluRay Technology. [P2.088]

In this work we present for the first time a centrifugal microfluidic system for the detection of proteins in blood using a low cost (< 10$) blu-ray pickup head for detection. The detection method is based on functionalized paramagnetic nanobeads using a magneto-optical principle. This platform is very well suited for low-cost point-of-care applications. We use a completely novel detection method based on the modulation of light due to the formation and disruption of chains of magnetic nanobeads [1]. The surface of the beads is functionalized in order to capture the target proteins. If the target is present in the sample, the beads form clusters. When exposed to an external oscillating magnetic field, the beads physically rotate to align themselves with the magnetic field and thus resulting in a modulation of light passing through the suspension. The modulation is dependent on the frequency of the external magnetic field and the size of the particle clusters. This effect is exploited to implement an agglutination–type assay on a microfluidic disc which integrates all steps necessary to process whole blood samples (fig. 1). Figure 1: (a) shows the microfluidic disc comprising of three parts. A detailed view of one of the nine independent microfluidic structures is shown in (b). Experiments were conducted using the following protocol (fig. 2): 1. Loading of blood and bead suspension 2. Separation of plasma 3. Mixing of plasma and beads 4. Agglutination 5. Readout Figure 2: Process steps of blood separation and protein detection on disc. (a) loading of blood and bead suspension. (b) blood separation. (c) transfer and mixing of plasma. (d) agglutination of beads. (e) readout. (f) setup of the reader. Scale bars are 5 mm. To demonstrate the capability of our detection platform to measure proteins we used biotinylated anti-streptavidin antibodies (0.0325 – 1.625 nM) and streptavidin coated magnetic beads (80 nm diameter) for detection. Antibodies were spiked in PBS (fig. 3a) and plasma (fig. 3b). Figure 3: (a) shows the results of the biotinylated anti-streptavidin IgG spiked in PBS buffer. (b) shows the results of the same IgG spiked in plasma. All protocol steps and measurements have been carried out on disc. All experiments yielded comparable results, thus demonstrating the capabilities to perform all necessary steps to detected proteins in whole blood using low-cost components and a minimum of user interaction. Currently we are working on the detection of clinically relevant proteins such as CRP in whole blood. References [1] M. Donolato, P. Vavassori and M. F. Hansen. Magneto-Optical Detection of Magnetic Nanobeads in a Microfluidic Channel. Proceedings of MicroTAS 2014, pp. 272 – 274 *these authors contributed equally