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

Exploring an effective sensor to detect Fe3+ and phytic acid (PA) is of great importance because the levels of Fe3+ and PA have a vital impact on human health. Herein, we report a metal-free fluorescent nanoprobe for sensitive and selective sensing of Fe3+ 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 Fe3+ and PA based on the introduction and elimination of electron transfer effect. The addition of Fe3+ can cause non radiative electron transfer associated with fluorescence quenching of SQDs, while the addition of PA enables SQDs/Fe3+ complex release Fe3+ to recover the fluorescence of SQDS. By utilizing these SQDs as a fluorescent nanoprobe, it shows good linear relationship for Fe3+ and PA in the range of 0.05-120 mu M and 0-12 mu M, respectively. Moreover, its limit of detection (LOD) for Fe3+ 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 SQDsbased sensor to detect PA in fresh carrot and lettuce samples was examined with satisfactory performance.

Automated summary

Exploring an effective sensor for detecting Fe3+ and phytic acid (PA) is crucial for human health, and a metal-free fluorescent nanoprobe based on sulfur quantum dots (SQDs) has been developed for this purpose. The SQDs show responsive and selective fluorescence behavior towards Fe3+ and PA, with a good linear relationship and low limits of detection. The sensor was successfully used to detect PA in fresh carrot and lettuce samples.