A highly selective fluorescent biosensor based on sulfur quantum dots for iron (III) detection

In this study, sulfur quantum dots (SQDs) were synthesized via an easy one-step solvothermal approach, and for the first time polyvinylpyrrolidone (PVP) was used as a capping agent that resulted in the synthesized SQDs with ultra-small size (3.57 nm), good photoluminescence, excellent stability, hydrophilicity, and rich functional groups surface. As a result of these features, SQDs were able to detect ferric ions (Fe3+) with fast rate responsiveness in acidic environments (pH=3) and in the existence of interferents with a limit of detection (LOD) of 48 nM and the detection range of 0 to 250 mu M. Moreover, the cytotoxicity of SQDs was examined based on fibroblast normal cells (L929) and cervical cancer cells (HeLa). SQDs showed biocompatibility and extremely low toxicity towards both cell types even at high concentrations (250 mu g/mL). This proposed method showed that SQDs as simple and portable sensors are promising for Fe3+ detection that can be applied in acidic environments and real samples with acceptable results.