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We present a biosensing platform for the detection of proteins based on agglutination of aptamer coated magnetic nano- or microbeads. The assay, from sample to answer, is integrated on an automated, low-cost microfluidic disc platform. This ensures fast and reliable results due to a minimum of manual steps involved. The detection of the target protein was achieved in two ways: (1) optomagnetic readout using magnetic nanobeads (MNBs); (2) optical imaging using magnetic microbeads (MMBs). The optomagnetic readout of agglutination is based on optical measurement of the dynamics of MNB aggregates whereas the imaging method is based on direct visualization and quantification of the average size of MMB aggregates. By enhancing magnetic particle agglutination via application of strong magnetic field pulses, we obtained identical limits of detection of 25pM with the same sample-to-answer time (15min 30s) using the two differently sized beads for the two detection methods. In both cases a sample volume of only 10µl is required. The demonstrated automation, low sample-to-answer time and portability of both detection instruments as well as integration of the assay on a low-cost disc are important steps for the implementation of these as portable tools in an out-of-lab setting., (Copyright © 2016 Elsevier B.V. All rights reserved.)

There is an increasing need for portable and low-cost diagnostic devices for detecting inflammatory/infectious diseases in a rapid and user-friendly fashion. Here, we present a lab-on-a-disc solution, which performs automated sample pre-treatment and combinedly detects small molecules and counts cells in a whole blood sample with a volume of 8.75 μL with a sample to answer time of 14 min. It is used to detect two common inflammation/infection biomarkers, C-reactive protein (CRP) and peripheral blood mononuclear cell (PBMC) count. The whole blood sample was separated into plasma and PBMC fractions using density gradient centrifugation and centrifugo-pneumatic valving. On-disc CRP detection was performed in the extracted plasma using a CRP-antibody-functionalized magnetic nanobead (MNB)-based agglutination assay and a Blu-ray-based optomagnetic detection unit. On-disc PBMC scanning and quantification was performed using an optical imaging unit. Both detection units were integrated on the centrifugal platform and the entire study was automated in order to ensure reliability of the assay and user-friendliness of the method. We measured the CRP level of subjects with different CRP levels and obtained approximately 73% PBMC extraction efficiency compared to hospital results. The concurrent/combined detection of these two common biomarkers in an automated microfluidic platform with integrated detection units and with a low sample-to-answer time is a significant step forward towards a low-cost, out-of-lab, and portable tool to detect multiple biomarkers of significantly different nature (molecules and cells). [ABSTRACT FROM AUTHOR]