Magnetoplasmonic photonic arrays for rapid and selective colorimetric detection of chloride ions in water

The rapid and efficient detection of chloride (Cl-) ions is crucial in a variety of fields, making the development of advanced sensing methods such as colorimetric sensors an imperative advancement in analytical chemistry. Herein, a novel, selective, and straightforward paper-based colorimetric sensing platform has been developed utilizing an amorphous photonic array (APA) of magnetoplasmonic Ag@Fe3O4 nanoparticles (MagPlas NPs) for the detection of Cl- in water. Taking advantage of the highly responsive APA, the key principle of this sensing method is based on the chemical reaction between Ag+ and Cl-, which results in the precipitation of high-refractive index (RI) AgCl. This assay, distinct from typical plasmonic sensors that rely heavily on nanoparticle aggregation/anti-aggregation, is premised on the precipitation reaction of Ag+ and Cl-. In the presence of Cl-, a rapid, distinctive color alteration from royal purple to a dark sky blue is visually observable within a short time of a few minutes, eliminating the necessity for any surface modification procedures. Comprehensive assessments substantiated that these sensors display commendable sensitivity, selectivity, and stability, thereby establishing their effective applicability for Cl- analysis in various technological fields. Introducing a rapid, color-changing assay for Cl- detection in water, this study showcases high sensitivity, selectivity, and stability, suitable for both environmental and biomedical applications, and offers versatility in detecting various anions for on-site screening.

Automated summary

This study introduces a novel, selective, and straightforward paper-based colorimetric sensing platform for the detection of chloride ions in water. The method utilizes magnetoplasmonic nanoparticles and is based on the chemical reaction between silver ions and chloride ions. The assay demonstrates high sensitivity, selectivity, and stability, making it applicable for chloride analysis in various technological fields.