Design And Synthesis Of Dual-emissive Fluorescence Probes For Detection Of Water Pollutants

Fluorescence spectroscopy has many advantages,including high sensitivity,good selectivity,and operational simplicity,so it is widely used in environmental testing,biomedicine and other fields.Based on the increasingly serious environmental pollution problem,in this study,we aimed to develop dual-emissive fluorescence probes by using carbon dots and semiconductor nanocrystalline quantum dots for selective detection of Fe³⁺ions,phytic acid?PA?and Cu²⁺ions.Using transmission electron microscope,fluorescence spectrum,infrared spectrum,scanning electron microscope and other testing instruments to characterize the morphology,stability,detection range and detection limit of the dual-emissive ratiometric fluorescent probes.The specific recognition ability of the fluorescent probes were verified by the interference experiment.?1?The water soluble fluorescence carbon dots were prepared via the hydrothermal treatment of citric acid and lysine.The CdSe@SiO₂ were spherical particles and prepared by reversed-phase microemulsion method.The synthesis of the dual-emissive ratiometric fluorescent probe CdSe@SiO₂-CDs relied on the covalent linking of carbon dots to the surface of CdSe@SiO₂.The fluorescence of the carbon dots was effectively quenched by Fe³⁺ions via a photoinduced electron transfer?PET?process.Fe³⁺ions could selectively bind to PA,thus leading to the recovered fluorescence of the carbon dots in the presence of Fe³⁺ions.This probe can realize the specific recognition of Fe³⁺ions and PA.The ratiometric probe enabled the selective detection of Fe³⁺within 9-120?M and a limit of detection of 0.26?M.Besides,it also enabled the selective detection of PA within 0.08-1.6 mM with a limit of detection of1.5?M.The standard addition method can confirm the promising application of the developed dual-emissive ratiometric fluorescent probe.?2?The oil soluble carbon dots with siloxane group were prepared by high temperature pyrolysis method.The CdTe quantum dots was linked to the CDs@SiO₂nanoparticles to form the dual-emissive fluorescence probe CDs@SiO₂-CdTe.This probe could realize the specific recognition of Cu²⁺ions.The ratiometric probe enabled the selective detection of Cu²⁺ions within 0.82-25?M with a limit of detection of 0.053?M.The fluorescent color of the dual-emissive fluorescence probe has changed obviously under the ultraviolet lamp,which proved it can realize visual detection of Cu²⁺ions.