Abstract

Lab-on-Blu-Ray: Low-Cost Analyte Detection on a Disk

Marco Donolato, Researcher/CTO, Blue Sense Diagnostics

In this work, we present for the first time a centrifugal microfluidic system for the detection of analytes in blood using a low cost (< 10$) blu-ray pickup head for detection. The microfluidic operations are carried out on a disk, while the detection method is based on optical measurements of the rotation dynamics of functionalized magnetic nanobeads (MNBs) in an oscillating uniaxial magnetic field. The system has been demonstrated both for antibody based protein detection, aptamer based ATP detection and amplified oligonucleotide detection. The readout method is based on the light modulation due to the formation and disruption of chains of MNBs. As in traditional latex particle-based immuno-agglutination assays, the MNBs form clusters if the target is present in the sample. Since the beads are magnetic the agglutination process can be accelerated and the optically detected MNB response to an external AC field is used instead of traditional turbidimetric variation. This provides higher sensitivity, as the detection of few MNB-clusters is not interfered by background signals from single MNBs. Figure 1 shows the set-up configuration, where a Sony blu-Ray pickup head (the same as in Playstation 3) is used as a laser source (?=405nm) and as a reader, as the light beam is reflected back through a mirror. Two electromagnets are used to produce the AC modulated field and a data acquisition card is used to analyze the signal. The process of blood separation on-disk is shown in. The plasma is mixed with MNBs in the detection chamber and the optomagnetic signal is measured after a magnetic incubation step.We present two different readout approaches. In the first case, antibody coated MNBs agglutinate due to the presence of an antigen and the amount of clusters is then quantified and related to the target protein concentration. In the second case, a reverse approach is used to detect small molecules as adenosine-5'-triphosphate (ATP). Aptamer-functionalized MNBs and