Engineering of onsite point-of-care testing of Fe3+ with visual ratiometric fluorescent signals of copper nanoclusters-driven portable smartphone

Abstract

Development of efficient point-of-care testing (POCT) toward heavy metals is an effective way to establish warning-early mechanisms against environmental and food safety risks, safeguarding public health. Here, we engineered an intelligent smartphone-based POCT platform for detecting of Fe 3+ in environmental and food matrices. We firstly synthesized bovine serum albumin-protected copper nanoclusters (BSA-CuNCs) to assemble [Ru(bpy) 3 ] 2+ for obtaining dual-emission BSA-CuNCs@ [Ru(bpy) 3 ] 2+ via electrostatic attraction. However, Fe 3+ triggered the fluorescence quenching of BSA-CuNCs at 452 nm through aggregation-induced quenching (ACQ) effect, while there was a negligible influence on the emission of [Ru(bpy) 3 ] 2+ at 624 nm, obtaining a ratiometric fluorescent responding to Fe 3+ . By integrating into a smartphone-based gadget, we achieved fluorescence color varies from cyan-blue to red, which were transduced by the Color Picker APP into the RGB values that displayed linear relationship to Fe 3+ concentration among 0.0 – 15.0 μM ( R 2 = 0.995), with a detection limit of 0.086 μM and a response time within 3.0 min. Notably, this portable platform has been used to gauge Fe 3+ in tap water and spirits, whose results agreed with ICP-MS analysis, proving its practicability for onsite determination of Fe 3+ in safeguarding environmental and food safety. • Designing a copper nanoclusters-based ratiometric fluorescent nanoprobe for precisely recognizing Fe 3+ . • Developing smartphone-based intelligent automatic POCT platform for onsite traceability analysis of Fe 3+ . • Exhibiting good practicability of smartphone-based POCT platform for Fe 3+ in environmental and food analysis.