Low-cost flow cell for multiplexed electrochemical detection of magneto-inmunoassays.

Abstract

This work describes the design and fabrication of a miniaturized flow cell for the chronoamperometric detection of Mieloperoxidase (MPO), a cardiac biomarker. The flow cell consists of a microfluidic cartridge made of a series of cyclo-olefin polymer (COP) and pressure sensitive adhesive (PSA) layers, featuring four independent channels and their corresponding sets of gold microband electrodes. The cartridge is inserted into a holder that provides microfluidic and electrical connections, and presents a row of switchable magnets (Figure 1). Except for the microelectrodes, which are microfabricated, the system has been produced using rapid prototyping techniques outside a clean room environment. This lowered its production costs drastically. In order to assess the device performance, two MPO assays were performed in parallel using immunofunctionalized magnetic beads. While one of them consists of MPO immunocapture and straightforward detection of MPO endogenous peroxidase activity (MPOACTIV), the other one is based on a sandwich immunoassay using an HRP-labeled antibody for detection of total MPO (MPOMASS). Working under flow conditions allowed us to compare the efficiency of two different detection strategies: measurement of steady state currents and generation of stop-flow peaks (in which flow retention for a fixed time results in building up of the enzymatic product, improving detection significantly). The results obtained show that the microfluidic platform described here is capable of multiplexed biomarker determination, which is crucial for diagnosis and stratification of heart diseases.

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Title:
Dual chronoamperometric detection of enzymatic biomarkers using magnetic beads and a low-cost flow
cell
Authors & affiliations:
Llibertat Abad
1
, J. Moral-Vico
1
, Jaume Barallat
2
, Rosa Olivé-Monllau
1
, Francesc Xavier Muñoz-
Pascual
1,3
, Amparo Galán Ortega
4
, Javier del Campo
1
, Eva Baldrich
1,5
1
Institut de Microelectrònica de Barcelona (IMB-CNM, CSIC), Campus Universitat Autònoma de
Barcelona, Bellaterra 08193, Spain.
2
Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol. Badalona, Spain.
3
Hospital Germans Trias i Pujol, Badalona, Spain.
4
MATGAS A. I. E. Campus UAB, 08193 Bellaterra, Spain
5
Diagnostic Nanotools. Molecular Biology and Biochemistry Research Center for Nanomedicine
(Cibbim-Nanomedicine). Vall d’Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona,
Passeig de la Vall d’Hebron 119-129,08035 Barcelona, Spain
Abstract: (Your abstract must use Normal style and must fit in this box. Your abstract should be no longer than 300 words. The
box will ‘expand’ over 2 pages as you add text/diagrams into it.)
This work describes the design and fabrication of a miniaturized flow cell for the chronoamperometric
detection of Mieloperoxidase (MPO), a cardiac biomarker. The flow cell consists of a microfluidic
cartridge made of a series of cyclo-olefin polymer (COP) and pressure sensitive adhesive (PSA) layers,
featuring four independent channels and their corresponding sets of gold microband electrodes. The
cartridge is inserted into a holder that provides microfluidic and electrical connections, and presents a row
of switchable magnets (Figure 1). Except for the microelectrodes, which are microfabricated, the system
has been produced using rapid prototyping techniques outside a clean room environment. This lowered its
production costs drastically. In order to assess the device performance, two MPO assays were performed
in parallel using immunofunctionalized magnetic beads. While one of them consists of MPO
immunocapture and straightforward detection of MPO endogenous peroxidase activity (MPO
ACTIV
), the
other one is based on a sandwich immunoassay using an HRP-labeled antibody for detection of total MPO
(MPO
MASS
). Working under flow conditions allowed us to compare the efficiency of two different
detection strategies: measurement of steady state currents and generation of stop-flow peaks (in which
flow retention for a fixed time results in building up of the enzymatic product, improving detection
significantly). The results obtained show that the microfluidic platform described here is capable of

Important notes:
Do NOT write outside the grey boxes. Any text or images outside the boxes will
be deleted.
Do NOT alter the structure of this form. Simply enter your information into the boxes. The form will be
automatically processed – if you alter its structure your submission will not be processed correctly.
Do not include keywords – you can add them when you submit the abstract online.
multiplexed biomarker determination, which is crucial for diagnosis and stratification of heart diseases.
Fig. 1. (a) Images of the microfluidic chip and holder reported in this work. From left to right, holder
cover displaying electric and fluidic connections, holder base with the array of magnets and alignment
pins, and a microfluidic cartridge. (b) Image of the same device after assembly. (c) Scheme of the
different components of the cartridge. The red dashed lines correspond to the fluid path across the chip
and over the electrodes for one of the four channels.