Sulfur quantum dots: A novel fluorescent probe for sensitive and selective detection of Fe3+ and phytic acid

Exploring an effective sensor to detect Fe 3+ and phytic acid (PA) is of great importance because the levels of Fe 3+ and PA have a vital impact on human health. Herein, we report a metal-free fluorescent nanoprobe for sensitive and selective sensing of Fe 3+ and PA based on the sulfur quantum dots (SQDs). The SQDs with high fluorescence quantum yield (17.6%) and low cytotoxicity can be directly synthesized from cheap elemental sulfur by one-pot reaction. The SQDs display responsive and selective fluorescence “on–off-on” behavior towards Fe 3+ and PA based on the introduction and elimination of electron transfer effect. The addition of Fe 3+ can cause non-radiative electron transfer associated with fluorescence quenching of SQDs, while the addition of PA enables SQDs/Fe 3+ complex release Fe 3+ to recover the fluorescence of SQD S . By utilizing these SQDs as a fluorescent nanoprobe, it shows good linear relationship for Fe 3+ and PA in the range of 0.05–120 µM and 0–12 µM, respectively. Moreover, its limit of detection (LOD) for Fe 3+ and PA can reach as low as 102 and 73.5 nM, respectively, which compares favorably to many reported fluorescent probes. Additionally, the use of this SQDs-based sensor to detect PA in fresh carrot and lettuce samples was examined with satisfactory performance.