Printed colorimetric chemosensor array on a 96-microwell paper substrate for metal ions in river water

Abstract

Here, we propose a printed 96-well microtiter paper-based chemosensor array device (PCSAD) to simultaneously detect metal ions for river water assessment. Colorimetric chemosensors for metal ions have been designed based on molecular self-assembly using off-the-shelf catechol dyes and a phenylboronic acid (PBA) derivative. The colorimetric self-assembled chemosensors consisting of catechol dyes and a PBA derivative on a 96-well microtiter paper substrate demonstrated various color changes according to the disassembly of the ensembles by the addition of nine types of metal ions. An in-house-made algorithm was used to automate imaging analysis and extract color intensities at seven types of color channels from a captured digital image, allowing for rapid data processing. The obtained information-rich inset data showed fingerprint-like colorimetric responses and was applied to the qualitative and quantitative pattern recognition of metal ions using chemometric techniques. The feasibility of the 96-well microtiter PCSAD for environmental assessment has been revealed by the demonstration of a spike-and-recovery test against metal ions in a river water sample.

Methodologies for Spontaneous Preparation of Chemosensors and Their Arrays Using Off‐the‐Shelf Reagents

“…The detection mechanism was also applied to a PCSAD for the on-site detection of metal ions by an imaging analysis, which successfully analyzed the metal ion levels in river water. [54] In a further attempt, a combination of a catechol fluorophore and an optical manipulator was used to fabricate a ratiometric self-assembled chemosensor for the quantification of toxic metal ions. [113] The indicator-release-type displacement assays (Figures 7 (a) and (b)) provide only simple switching profiles with ON-OFF or OFF-ON responses because the indicators do not contribute to target binding units.…”

“…In this assay, a fluorescent ensemble was formed by 53 and 54, with an ON-OFF response derived from PeT. [83,[117][118] In the proposed strategy, the absolute fluorescence spectra of the catechol fluorophore (54) were purposely manipulated by the formation with 53. Owing to the higher binding affinity of the catechol fluorophore to metal ions compared to that of the phenylboronic acid derivative, the release of 53 from the complex of 53 and 54 occurred along with the coordination of 54 and the target metal ion (Figure 15(a)).…”

“…The results of regression analysis using the SVM showed the prediction accuracy of unknown concentrations at the sub‐ppm level. The detection mechanism was also applied to a PCSAD for the on‐site detection of metal ions by an imaging analysis, which successfully analyzed the metal ion levels in river water [54] …”