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

Synthesis of Fluorescent Sulfur Quantum Dots for Bioimaging and Biosensing

“…This is because O 2 can oxidize Sx 2− ions to zero-valent S atoms ( Figure 1D ). Under the condition of oxygen acceleration, they also synthesized SQDs by using different stabilizers such as carboxymethyl cellulose (CMC) ( Duan et al, 2020 ), polyvinyl alcohol (PVA) ( Lei et al, 2021 ), and hydroxypropyl-β-cyclodextrin (HP-β-CD) ( Huang et al, 2021a ). It was found that different stabilizers can endow the SQDs with distinct surface properties.…”

“…For instance, Zhou’s groups examine the toxicity of different SQDs using MTT assay based on 293T normal cells and HeLa cancer cells. They found that SQDs stabilized with different capping agents (e.g., PEG, CMC, PVA, and HP-β-CD) displayed high cell viability (90%) both for 293T and HeLa cells when the concentration of SQDs was relatively low (0–50 μg/ml) ( Duan et al, 2020 ; Huang et al, 2021a ; Lei et al, 2021 ; Song et al, 2020 ). When the concentration of SQDs was up to 200 μg/ml, the cell viability still exceeded 80%, suggesting the low cytotoxicity of SQDs ( Figure 2A ).…”

“…In this regard, fluorescent SQDs are expected to be attractive fluorescent nanoprobe for biosensing applications because of their excellent fluorescence performance, unique composition, and low toxicity. Until now, the utilization of SQDs as a fluorescent probe for sensing bio-related molecules and metal ions has been intensively studied ( Arshad and Palashuddin, 2020 ; Huang et al, 2021a ; Ma et al, 2021 ; Sheng et al, 2021 ; Lu et al, 2022 ; Yan et al, 2022 ).…”

“…For sensing metal ions, SQDs synthesized under different reaction conditions have presented sensitive and selective fluorescence detection properties for a variety of metal ions, such as Cr(VI) ( Duan et al, 2020 ; Zhang et al, 2020 ), Fe 3+ ( Huang et al, 2021a ; Lei et al, 2021 ), Co 2+ ( Wang S. et al, 2019 ), Hg 2+ ( Qiao et al, 2020 ), and Zn 2+ ions ( Zhao and Fan, 2020 ). For example, Zhou and co-workers found that the CMC-capped SQDs showed sensitive fluorescence quenching behavior toward Cr(VI) due to the existence of strong IFE.…”

“…Great progress has been made in the synthesis of SQDs since it was first reported in 2018 ( Shen et al, 2018 ) that SQDs could be synthesized directly from cheap and abundant elemental S. Many researchers have devoted themselves to exploiting the application potential of SQDs. Up to now, SQDs have exhibited application potential in numerous fields, such as fluorescence detection ( Huang et al, 2021a ; Sheng et al, 2021 ), bioimaging ( Arshad et al, 2021 ; Zhang et al, 2019 ), light-emitting diodes ( Wang H. et al, 2019 ), fluorescent polymer composites ( Song et al, 2020 ), photocatalysis ( Li et al, 2014 ), and antibacterial materials ( Wang et al, 2021 ). Among them, SQDs have received special attention in bioimaging and biosensing because of their good biocompatibility, low toxicity, and unique surface properties.…”