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Title

Equipment-Free Detection of K + on Microfluidic Paper-Based Analytical Devices Based on Exhaustive Replacement with Ionic Dye in Ion-selective Capillary Sensors

Authors
Citterio, Daniel
Published in ACS Sensors. 2019
Abstract A distance-based analysis of potassium ion (K⁺) is introduced that is performed on a microfluidic paper-based analytical device (μPAD) coupled to an ion-selective capillary sensor. The concept is based on two sequential steps, the selective replacement of analyte ion with an ionic dye, and the detection of this dye in a distance-based readout on paper. To achieve the first step, the capillary sensor holds a poly(vinyl chloride) (PVC) membrane film layer plasticized by dioctyl sebacate (DOS) that contains the potassium ionophore valinomycin, a lipophilic cation-exchanger and the ionic indicator Thioflavin T (ThT) on its inner wall. Upon introduction of the sample, K⁺ in the aqueous sample solution is quantitatively extracted into the film membrane and replaced with ThT. To convert the ion exchange signal into a distance-based analysis, this solution was dropped onto the inlet area of a μPAD to flow the ThT along a channel defined by wax printing, resulting in the electrostatic binding of ThT to the cellulose carboxylic groups. The initial amount of K⁺ determines the amount of ThT in the aqueous solution after ion-exchange, and consequently the distance of ThT-colored area reflects the sample K⁺ concentration. The ion exchange reaction was operated in a so-called “exhaustive sensing mode” and gave a distinct response in a narrow range of K⁺ concentration (1–6 mM) that cannot be achieved by the classical optode sensing mode. The absence of hydrogen ions from the equilibrium competition of the capillary sensor contributed to a complete pH-independence, unlike conventional optodes that contain a pH sensitive indicator. A very high selectivity for K⁺ over Na⁺ and Ca²⁺ has been confirmed in separate solutions and mixed solutions tests. K⁺ measurements in pooled serum samples at concentrations between 2 and 6 mM are successfully demonstrated on a temperature controlled support.
Keywords Capillary sensorIon-selective membranePaper-based analytical devicesPotassium detectionSerum measurement
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Other version: http://pubs.acs.org/doi/10.1021/acssensors.8b01521
Structures
Research group Groupe Bakker
Project FNS: 200021_175622
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(ISO format)
SODA, Yoshiki, CITTERIO, Daniel, BAKKER, Eric. Equipment-Free Detection of K + on Microfluidic Paper-Based Analytical Devices Based on Exhaustive Replacement with Ionic Dye in Ion-selective Capillary Sensors. In: ACS Sensors, 2019. https://archive-ouverte.unige.ch/unige:114491

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Deposited on : 2019-02-22

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