A smartphone-integrated ratiometric fluorescence sensor for visual detection of cadmium ions.

A novel fluorescence sensing platform was fabricated for visual detection of cadmium ions (Cd2+) with excellent stability and portability. In this protocol, dual-emission ratiometric fluorescence probe were constructed based on silicon oxide-coated copper nanoclusters (CuNCs@SiO2) as a signal reference and cadmium telluride quantum dots (CdTe QDs) as signal response, thereby greatly improving the accuracy of test results. The level of Cd2+ can be reported within a wide linear range from 0.010 mg·L-1 to 2.0 mg·L-1 with a sensitive detection limit of 1.1 μg·L-1 (2.75 μg·kg-1) and a quick sample-to-answer monitoring time of 6 min, which was quite qualified for regularly monitoring Cd2+. Moreover, aiming to attain portable analysis, the smartphone as colorimetric reader and analyzer were also utilized for rapidly analyzing Cd2+ by capturing the change in fluorescence color. Additionally, benefiting from the strong combination of 1, 10-phenanthroline (Phen) and Cd2+, the fluorescence probe showed excellent anti-interference activities for Cd2+ assay in complex oyster matrix. Overall, the sensing platform had significant stability, specificity and sensitivity, offering a promising potential for conveniently evaluating the quality of marine bivalves polluted with Cd2+.