Magnetic bead actuated microfluidic immunoassay platform for sensitive detection of biomarkers and pathogens

• Auf magnetischen Partikeln basierte mikrofluidische Immunoassay-Plattform für den empfindlichen Nachweis von Biomarkern und Krankheitserreger

Gottheil, Raiah; Mokwa, Wilfried (Thesis advisor)

Aachen : Publikationsserver der RWTH Aachen University (2014)
Dissertation / PhD Thesis

Aachen, Techn. Hochsch., Diss., 2014

Abstract

Laboratory diagnostics are an essential and indispensible component of modern medicine. Large central laboratories have led to vast improvements in health care and now play a key role in the diagnosis and monitoring of therapy. Recent trends, however, indicate a rising need for on-site testing, for instance, in medical practices, operating theatres, outpatient clinics or emergency rooms. Cleverly engineered, compact products made possible due to advances in nanotechnology, molecular diagnostics, information technology and microfluidics can now meet this demand. These portable devices offer immediate access to a range of diagnostic parameters and thus help the medical caregiver to diagnose a case faster and make timely decisions about therapy. The commercial availability of compact and portable diagnostic devices has led to the widespread practice of what is now termed ‘Point-of-Care Testing’ (POCT). In this work, a microfluidic based platform for sensitive and quantitative detection of diagnostic targets suitable for POCT is reported. The analyte particles are detected through a magnetic bead based fluorescence sandwich immunoassay. The beads constitute both the solid phase for immobilization of capture molecules and enable active manipulation by external magnetic fields. Rather than pumping various assay buffers into a chamber, the solid phase is moved through stationary aqueous buffer contained in several chambers. This is done by focusing the beads into a tiny aggregate, which then is moved through capillary stop valve structures separating the chambers. After traversing such a valve, the bead aggregate is re-dispersed to form pearl-chain microstirrers using rotating magnetic field actuation. In this way efficient and fast incubation and washing procedures are enabled. The assay scheme includes i) incubation of the sample with beads, ii) washing, iii) labeling with fluorescence detection antibody and iv) fluorescence detection. The cartridge itself is manufactured by cost effective microinjection molding and the periphery consist of magnets mounted onto translational stages. The assays chosen for the evaluation included a biomarker (Interleukin-8) and a viral pathogen (Hepatitis A Virus), which yielded detection limits of 1.49 pg/mL (0.188 pM) for the biomarker assay and 104 virus particles/ml for the virus assay. The biomarker assay run on the platform was as sensitive as the reference method (Luminex) and the virus assay showed an improvement in sensitivity in comparison to the employed reference (ELISA). With the biomarker assay though the assay time was not decreased, the total hands-on time and handling was reduced due to the automatisation. The virus assay demonstrated a 17.5 times increase in sensitivity compared to the reference method and was three times faster.

Institutions

• Chair of Materials in Electrical Engineering I and Institute of Materials in Electrical Engineering [611510]