Preparation And Application Of Sulfur Quantum Dots Based On Different Types Of Hydroxyl Ligand

Sulfur quantum dots（SQDs）are an emerging class of pure elemental quantum dots,which have attracted much attention due to their unique optical properties,excellent stability and non-toxicity.The main research is the synthesis of SQDs by solvothermal and reflux methods and functionalized with ligand passivation strategies to modulate their optical properties,achieving tunable tunable fluorescence emission from green to blue and solid-state fluorescence emission.The optical properties and luminescence mechanism of SQDs are characterized and discussed,and applied to the fields of drugs,dyes and antibiotics fluorescence sensing and optical devices are discussed.The research content mainly includes the following parts:1.The solid-state SQDs with resistance to self-quenching were obtained by increasing the spatial potential resistance between SQDs with polyethylene glycol（PEG）.Green fluorescent G-SQDs were prepared directly by the solvent method using sublimated sulfur,PEG as the precursor.After further H₂O₂ assisted etching,blue fluorescent B-SQDs were obtained.The tunable fluorescence emission and solid-state luminescence mechanism of SQDs were investigated by experiments and theoretical calculations.In addition,B-SQDs can be used for the specific detection of berberine hydrochloride in coptis chinensis extract.Solid-state SQDs have been successfully applied to the manufacturing of fluorescent films,fingerprint imaging and light-emitting diodes.2.The detection of the dye acridine orange（AO）was achieved by the dual response ofβ-SQDs ratiometric fluorescence(I₄₆₀/I₅₅₅)and scattered light(I₇₀₈).Blue fluorescentβ-SQDs were synthesized rapidly by a solvothermal method using sublimated sulfur as the sulfur source andβ-cyclodextrin（β-CD）as the passivator.Theβ-CD reduced the aggregation-induced quenching effect.Based on this,β-SQDs can be used as fluorescent sensors for AO and a series of characterizations demonstrate that the reaction between the two is caused by both internal filtration and static quenching.There was a good linear relationship between the AO concentration and the fluorescence intensity ofβ-SQDs,with detection limits as low as 0.41μM（0-60μL）and 2μM（60-90μL）derived from ratiometric fluorescence and 1.95μM（0-90μL）calculated from the scattered signal.3.Based on the strong affinity between the side hydroxyl groups of polyvinyl alcohol（PVA）and the surface of SQDs,the sublimated sulfur was dissolved in PVA solution and blue fluorescent A-SQDs were prepared by reflux method.A-SQDs showed excellent monodispersity,water solubility and fluorescence stability.A-SQDs exhibited unique fluorescence selectivity for oxytetracycline hydrochloride（OTC）with a detection limit of 3.38μM.Experiments confirmed that the sensing mechanism between the two is fluorescence resonance energy transfer.The A-SQDs were successfully applied to the determination of OTC in water,milk and pork samples with satisfactory recoveries and good relative standard deviations.