One-Step Synthesis of Label-Free Ratiometric Fluorescence Carbon Dots for the Detection of Silver Ions and Glutathione and Cellular Imaging Applications

Abstract

The construction of ratiometric fluorescence assay has displayed fantastic advantages in improving semi-quantitative visualization capability by presenting successive color changes. Herein, long-wavelength emission nitrogen-doped carbon dots (N-CDs) were developed for intrinsic ratiometric detection of silver ions (Ag+) and glutathione (GSH), accompanied by visualization fluorescence variation of orange and green. The label-free N-CDs were favorably obtained through one-step hydrothermal synthesis and displayed single long-wavelength emission at 618 nm under the excitation wavelength of 478 nm. Interestingly, a ratio rising peak emerges at 532 nm and the emission at 618 nm decreases with the introduction of Ag+, which exhibits ratiometric fluorescence emission characteristics (I 618nm/I 532nm) in the range of 0–140 μM with significant fluorescence varying from orange to green. Furthermore, the fluorescence of CDs@Ag­(I) can be effectively ratiometric recovered by virtue of a specific reaction of GSH with Ag+, which is accompanied by the fluorescence of the solution returning from green to orange. In addition, the N-CDs hold excellent biocompatibility which can be implemented as the visualization biosensing platform for intracellular determination of Ag+ and GSH, demonstrating that proposed N-CDs have tremendous potential in biological systems.

One-step synthesis of red-emitting carbon dots via a solvothermal method and its application in the detection of methylene blue

“…CDs, with their uorescence capability, are an attractive, carbon-based, functional materials aer the appearance of graphene, carbon nanotubes and nanodiamonds, 1 and they are widely used in various elds due to their multiple preparation routes, low toxicity, excellent biocompatibility and chemical stability. 2 In recent years, the long-wavelength emitting CDs have been the focus of researchers because of their promising potential in cell imaging, [3][4][5] in vivo imaging, 6,7 and in vivo labeling and diagnosis. 8,9 The reports and papers on green, yellow and orange emitting CDs [10][11][12] have been widely seen in published journals, but the ones on red-emitting CDs 13 are relatively scarce.…”

Fluorescent carbon dots as intracellular imaging probes

“…They usually have carbonaceous graphitic core of <10 nm with varying degrees of oxidation (Shi, Li, & Ma, ). These fluorescent carbon nanoparticles can be synthesized from various carbon precursors such as citric acid (He et al, ; Khan, Verma, Chethana, & Nandi, ; Lan et al, ; Liu, Tian, Tian, Wang, & Yang, ; Shangguan et al, ; Shi et al, ; Shu et al, ; Wu, Li, Ling, Huang, & Jia, ; Yang et al, ; Zhang et al, ), activated carbon powder (Chai et al, ), hyaluronic acid (Zhang et al, ), phenylene diamine derivative (Cheng et al, ; Hua, Bao, & Wu, ; Liu, Y., Duan, W., et al, 2017; Song, W., Duan, W., et al, 2017; Xia, Chen, Zou, Yu, & Wang, ), flour (Zhang et al, ), 2‐azidoimidazole (Tang, Lin, Li, & Hu, ), thiomalic acid (Safavi, Ahmadi, Mohammadpour, & Zhou, ), aminosalicylic acid (Song, Y., Zhu, C., et al, 2017), sodium alginate‐tryptophan (Zhu et al, ), neutral red‐triethyl amine (Jiao et al, ), capsicum (Chen et al, ), ethanol (Gao, Ding, Zhu, & Tian, ; Qu, Zhu, Shao, Shi, & Tian, ; Zhu, Qu, Shao, Kong, & Tian, ), (3‐aminopropyl) triethoxysilane (Zou et al, ), malic acid (Zhi et al, ), folic acid (Liu et al, ), and so on. Furthermore, various cost‐effective and simple procedures have been established for their preparation that include solvothermal treatment (Chen et al, ; Zhu et al, ), thermal degradation (Shi et al, ), high temperature reflux (Lan et al, ), microwave‐assisted synthesis (He et al, ; Tang et al, ), pyrolysis (Zhang et al, , ), and oxidative acid treatment (Safavi et al, ).…”

“…Furthermore, various cost‐effective and simple procedures have been established for their preparation that include solvothermal treatment (Chen et al, ; Zhu et al, ), thermal degradation (Shi et al, ), high temperature reflux (Lan et al, ), microwave‐assisted synthesis (He et al, ; Tang et al, ), pyrolysis (Zhang et al, , ), and oxidative acid treatment (Safavi et al, ). Following these approaches, fluorescent carbon nanoparticles are synthesized with wide range of emission from ultraviolet to visible to near‐infrared (Cheng et al, ; Jiao et al, ; Lan et al, ). In particular, the fluorescence property of these carbon nanoparticles has been tuned by varying chemical composition, particle size, and introducing surface defects.…”

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

“…The NIR emission of 678 nm was a signal peak quenching by Hg(II), while an emission peak of 470 nm was constant to Hg(II) used as a reference. Dong et al [82] constructed a ratiometric fluorescence assay with N-CDs to detect Ag(I) based on the ratio (I 618 /I 532 ) of rising peak emerges at 532 nm and the decreasing peak at 618 nm with the introduction of Ag(I). Ding et al [83] prepared multicolor CDs with tunable fluorescence emissions from violet to red without obvious compromising the fluorescence intensities.…”