Effective Determination of Zn²⁺, Mn²⁺, and Cu²⁺ Simultaneously By Using Dual‐Emissive Carbon Dots as Colorimetric Fluorescent Probe

Abstract

Dual‐emissive fluorescent glutathione carbon dots (GSH‐CDs) have been synthesized by a green hydrothermal method and used as a colorimetric fluorescent probe for the multi‐detection of Zn2+, Mn2+, and Cu2+ individually or simultaneously. The GSH‐CDs exhibit dual fluorescence emission at 460 and 683 nm, which results in cyan fluorescence emission under UV light. The dual‐emissive GSH‐CDs can be used as a multifunctional colorimetric fluorescent nanoprobe for precise and quantitative detection of Zn2+, Mn2+, and Cu2+ through a change in the color of the fluorescence. Upon interaction with Zn2+, the fluorescent color of the GSH‐CDs was transformed from cyan to pink. When exposed to Mn2+ or Cu2+, the fluorescence color was transformed from cyan to blue. When the three ions were present simultaneously, the cyan fluorescence emission changed to a nattier blue. The minimum limits of detection (LODs) for Zn2+, Mn2+, and Cu2+ were calculated to be 9.64, 3.24, and 1.7 nm, respectively. As far as we know, this is the first report of the use of dual‐emissive carbon dots for the multi‐detection of heavy‐metal ions. Moreover, the multi‐detection of Zn2+, Mn2+, and Cu2+ in real environmental water by GSH‐CDs was also investigated. In addition the GSH‐CDs can be applied in cell imaging.

A Review of Dual-Emission Carbon Dots and Their Applications

“…Due to the large variety of precursors and simple/environmentally friendly synthesis process, the hydrothermal/solvothermal method is widely used in DE-CDs synthesis. For instance, Yu et al synthesized cyan fluorescent DE-CDs through the solvothermal treatment of glutathione (GSH) and formamide at 160 • C for 1 h [56]. As shown in Figure 2a, the obtained DE-CDs exhibit dual emission bands at 460 and 683 nm when excited with ultraviolet light (λ = 365 nm), which can be further applied for the multiple detection of heavy metal ions.…”

Synthesis Strategies, Optical Mechanisms, and Applications of Dual-Emissive Carbon Dots

“…For dual-emissive CDs, emission peaks at different wavelengths might show varying optical behaviors, which is of great significance in exploring multiplexed ratiometric sensors. By noticing the various fluorescent responsiveness of glutathionederived dual-emissive CDs towards Zn(II), Mn(II), and Cu(II), Chai's group first devised the ratiometric fluorescent sensor for individual or simultaneous detections of these metal ions [97]. As shown in Figure 8A, due to the selective quenching of blue or red emission, the color of the dual-emissive CDs transformed from cyan to pink and cyan to blue upon the additions of Zn(II) and Mn(II)/Cu(II), respectively.…”

Recent advances in fluorescence probes based on carbon dots for sensing and speciation of heavy metals

“…Fe(II) was detected by quenching effect on blue emitter at 386 nm; Bi(III) and Al(III) were detected and differentiated by the yellow emitter at 530 nm, which showed the decrease of fluorescence with the addition of Bi(III) and the enhancement of fluorescence with blue-shift upon the addition of Al(III). Chai et al [103] synthesized dual-emissive fluorescent GSH-CDs with emission at 460 and 683 nm, and successfully detected Zn(II), Mn(II), and Cu(II) ions based on their different response at two emission wavelengths of GSH-CDs. The addition of Zn(II) only would decrease peak intensities of both 460 and 683 nm, resulting in the fluorescent color turning from cyan to pink under UV light.…”