Renewable magnetic ion-selective colorimetric microsensors based on surface modified polystyrene beads

Sutasinee Apichai; Lu Wang; Kate Grudpan; Eric Bakker

doi:10.1016/j.aca.2019.10.011

Renewable magnetic ion-selective colorimetric microsensors based on surface modified polystyrene beads

Anal Chim Acta. 2020 Jan 15:1094:136-141. doi: 10.1016/j.aca.2019.10.011. Epub 2019 Oct 10.

Authors

Sutasinee Apichai¹, Lu Wang², Kate Grudpan³, Eric Bakker⁴

Affiliations

¹ Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211, Geneva, Switzerland; Center of Excellence for Innovation in Analytical Science and Technology, Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand.
² Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211, Geneva, Switzerland.
³ Center of Excellence for Innovation in Analytical Science and Technology, Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand.
⁴ Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211, Geneva, Switzerland. Electronic address: eric.bakker@unige.ch.

PMID: 31761040
DOI: 10.1016/j.aca.2019.10.011

Abstract

Magnetic ion-selective colorimetric microspheres based on surface modification of polystyrene beads (0.8 μm diameter) are reported for the first time. The common components of ion-selective optode sensing (chromoionophore, ion-exchanger and ionophore) and magnetic nanoparticles are adsorbed onto the surface of the polystyrene particles using a simple mixed solvent method. The average diameter of the magnetic microspheres is evaluated by dynamic light scattering as 0.79 ± 0.06 μm. The reversible microsensors are circulated by flow and accumulated at a single spot by an applied magnet to become observable by digital camera. Hue signals are extracted from the recorded images to quantify the ratio of protonated and deprotonated form of the chromoionophore, which is the basis for optode response. The resulting magnetic microsensors respond to K⁺ with excellent selectivity over the range of 10^-6 M to 10^-2 M and a response time of t₉₉ < 2.6±0.5 min above 10^-5 M. The use of solvatochromic dyes as pH independent transducers was not successful in this application.

Keywords: Colorimetry; Ion-selective optical sensor; Magnetic nanoparticle; Microspheres; Polystyrene bead; Potassium ion.