A ratiometric fluorescence sensor based on carbon dots and two-dimensional porphyrinic MOFs for on-site monitoring of sulfide

Sulfide is a widespread environmental contaminant present in nature and can cause damage to human beings even in microscale amounts. Despite the success of existing point-of-care testing (POCT) techniques, on-site accurate and sensitive detection of sulfide remains a challenge. Herein, we proposed a ratiometric fluorescent probe based on carbon dots (CDs) and two-dimensional porphyrin MOFs. Further, a sensitive, economical and visual potable device with smartphone was developed for the real-time and accurate detection of sulfide. Using Color Identifier App, the fluorescent image information captured by the smartphone was converted to color intensity (RGB values), with limit of detection (LOD) of 6.75 μM for sulfide. This portable smartphone-based sensor was successfully used for the highly sensitive detection of sulfide in lake and tap water samples. The advantages of simple operation, low cost, and good selectivity make the sensing platform suitable for on-site sulfide monitoring.