scholarly journals Electrochemical and Fluorescent Properties of Crown Ether Functionalized Graphene Quantum Dots for Potassium and Sodium Ions Detection

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2897
Author(s):  
Daniela Iannazzo ◽  
Claudia Espro ◽  
Angelo Ferlazzo ◽  
Consuelo Celesti ◽  
Caterina Branca ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Crown Ethers ◽  
Biological Fluids ◽  
Graphene Quantum Dots ◽  
Fluorescence Emission ◽  
Fluorescent Properties ◽  
Fluorescent Method ◽  
Basic Body ◽  
Emission Behavior ◽  
K Concentration

The concentration of sodium and potassium ions in biological fluids, such as blood, urine and sweat, is indicative of several basic body function conditions. Therefore, the development of simple methods able to detect these alkaline ions is of outmost importance. In this study, we explored the electrochemical and optical properties of graphene quantum dots (GQDs) combined with the selective chelating ability of the crown ethers 15-crown-5 and 18-crown-6, with the final aim to propose novel composites for the effective detection of these ions. The results obtained comparing the performances of the single GQDs and crown ethers with those of the GQDs-15-crown-5 and GQDs-18-crown-6 composites, have demonstrated the superior properties of these latter. Electrochemical investigation showed that the GQDs based composites can be exploited for the potentiometric detection of Na+ and K+ ions, but selectivity still remains a concern. The nanocomposites showed the characteristic fluorescence emissions of GQDs and crown ethers. The GQDs-18-crown-6 composite exhibited ratiometric fluorescence emission behavior with the variation of K+ concentration, demonstrating its promising properties for the development of a selective fluorescent method for potassium determination.

scholarly journals The Synthesis and Application of Nitrogen-Doped Graphene Quantum Dots on Brilliant Blue Detection

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Li Jin ◽  
Ying Wang ◽  
Fengkai Yan ◽  
Jianpo Zhang ◽  
Fangli Zhong
Keyword(s):  
Quantum Dots ◽  
Emission Spectrum ◽  
Graphene Quantum Dots ◽  
Fluorescence Emission ◽  
Fluorescence Decay ◽  
Brilliant Blue ◽  
Fluorescence Emission Spectrum ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Nitrogen-doped graphene quantum dots had been successfully synthesized and characterized by using transmission electron microscope, X-ray photoelectron spectroscopy, absorbance spectrum, fluorescence emission spectrum, and fluorescence decay curve. TEM results indicated that the diameters of the as-prepared nitrogen-doped graphene quantum dots were in the range of 2 - 5 nm and the lattice space is about 0.276 nm; Raman spectrum result indicated that there were two characteristic peaks, generally named D (~1408 cm−1) and G (~1640 cm−1) bands; both TEM and Raman spectrum results indicated that the as-synthesized product was graphene quantum dots. Deconvoluted high resolution XPS spectra for C1s, O1s, and N1s results indicated that there are -NH-, -COOH, and -OH groups on the surface of nitrogen-doped graphene quantum dot. Fluorescence emission spectrum indicated that the maximum fluorescence emission spectrum of nitrogen-doped graphene quantum dots was blue shift about 30.1 nm and the average fluorescence decay time of nitrogen-doped graphene quantum dots increased about 2 ns, compared with graphene quantum dots without doping of nitrogen. Then, the as-prepared nitrogen-doped graphene quantum dots were used to quantitatively analyze brilliant blue based on the fluorescent quenching of graphene quantum dots, and the effect of pH and reaction time on this fluorescent quenching system was also obtained. Under selected condition, the linear regression equations were F0/F=0.0087 (brilliant blue) + 0.9553 and F0/F=0.01205 (brilliant blue) + 0.6695, and low detection limit was 3.776 μmol/L (3.776 nmol/mL). Once more diluted N-GQDs (0.05 mg/mL) were used, the low detection limit could reach 94.87 nmol/L. Then, temperature-dependent experiment, absorbance spectra, and dynamic fluorescence quenching rate constant were used to study the quenching mechanism; all results indicated that this quenching process was a static quenching process based on the formation of complex between nitrogen-doped graphene quantum dots and brilliant blue through hydrogen bond. Particularly, this method was used to quantitatively analyze the wine sample, of which results have a high consistence with the results of the spectrophotometric method; demonstrating this fluorescence quenching method could be used in practical sample application.

Efficient synthesis of rice based graphene quantum dots and their fluorescent properties

RSC Advances ◽  
2016 ◽  
Vol 6 (28) ◽  
pp. 23518-23524 ◽  
Author(s):  
Hemen Kalita ◽  
Jeotikanta Mohapatra ◽  
Lina Pradhan ◽  
Arijit Mitra ◽  
Dhirendra Bahadur ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Carbon Source ◽  
Graphene Quantum Dots ◽  
Efficient Synthesis ◽  
Fluorescent Properties ◽  
Rice Grains ◽  
Green Approach

We present a facile green approach to synthesize monodisperse graphene quantum dots (GQDs) of sizes 2–6.5 nm using rice grains as a carbon source.

A fluorometric and colorimetric dual-mode sensor based on nitrogen and iron co-doped graphene quantum dots for detection of ferric ions in biological fluids and cellular imaging

2018 ◽  
Vol 42 (18) ◽  
pp. 14751-14756 ◽  
Author(s):  
Xue Xia Gao ◽  
Xi Zhou ◽  
Yu Feng Ma ◽  
Chun Peng Wang ◽  
Fu Xiang Chu
Keyword(s):  
Quantum Dots ◽  
Biological Fluids ◽  
Graphene Quantum Dots ◽  
Cellular Imaging ◽  
Ferric Ions ◽  
Dual Mode ◽  
Doped Graphene ◽  
Co Doped

A dual-mode sensing strategy based on N, Fe-GQDs for effective and selective detecting of Fe3+ and cellular imaging was developed.

scholarly journals Highly Fluorescent Nitrogen-Doped Graphene Quantum Dots’ Synthesis and Their Applications as Fe(III) Ions Sensor

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Fei Lu ◽  
Yi-hua Zhou ◽  
Li-hui Wu ◽  
Jun Qian ◽  
Sheng Cao ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Quantum Dots ◽  
Metal Ion ◽  
Graphene Quantum Dots ◽  
Fluorescence Emission ◽  
Blue Fluorescence ◽  
One Pot ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Nitrogen-doped graphene quantum dots (N-GQDs) with strong blue fluorescence and a high quantum yield of 88.9% were synthesized via a facile one-pot hydrothermal treatment with citric acid (CA) and ethylenediamine (EDA) as carbon and nitrogen sources, respectively. The blue fluorescence emission is independent of the excitation wavelengths. These N-GQDs dispersed well in water and ethyl alcohol and showed a highly selective and sensitive detection of hazardous and toxic Fe3+in the range of 1600μmol/L to 6000μmol/L through a fluorescence quenching process with a detection limit of 2.37μmol/L. Based on the excellent sensitivity and selectivity of N-GQDs to heavy metal ions, paper-based sensors can be fabricated by inkjet printing, which are rapid but low cost. So the visual instant on-site identification of heavy metal ion will be realized in the future.

Folic acid-functionalized graphene quantum dots with tunable fluorescence emission for cancer cell imaging and optical detection of Hg2+

2018 ◽  
Vol 42 (6) ◽  
pp. 4352-4360 ◽  
Author(s):  
Ruiyi Li ◽  
Xuan Wang ◽  
Zaijun Li ◽  
Haiyan Zhu ◽  
Junkang Liu
Keyword(s):  
Quantum Dots ◽  
Folic Acid ◽  
Functional Groups ◽  
Cancer Cell ◽  
Cell Imaging ◽  
Optical Detection ◽  
Graphene Quantum Dots ◽  
Fluorescence Emission ◽  
Electrical Characteristics ◽  
Functionalized Graphene

Functional groups may alter the optical and electrical characteristics of graphene quantum dots and lead to unusual properties and related applications.

A Strategy for Microwave-Controlled Release of Anticancer Drugs: (Fe3O4/nGO)@mSiO2/GQDs Nanocomposite Carrier Jointly Enhanced by nGO and GQDs

NANO ◽  
2020 ◽  
Vol 15 (06) ◽  
pp. 2050071
Author(s):  
Lian Huan Wang ◽  
Yu Mei Bu ◽  
Ye Liu ◽  
Ya Ping Yao ◽  
Zhen Feng Yang ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Quantum Dots ◽  
Controlled Release ◽  
Microwave Irradiation ◽  
Loading Rate ◽  
Drug Carrier ◽  
Graphene Quantum Dots ◽  
Fluorescence Emission ◽  
Magnetic Core ◽  
Magnetic Performance

We constructed a multifunctional (Fe3O4/nGO)@mSiO2/GQDs drug carrier for loading and microwave-controlled release of an etoposide (VP16) as the anticancer drug. This nanocomposite consisted of magnetic core Fe3O4, microwave-absorbing nanographene oxide (nGO), fluorescent graphene quantum dots (GQDs) and intermediate barrier layer (mesoporous silica). It has a large surface area of 359.8[Formula: see text]m2/g, excellent fluorescence emission and ample magnetic performance of 36.00[Formula: see text]emu/g. After microwave irradiation for 140 s, the temperature of (Fe3O4/nGO)@mSiO2/GQDs nanoparticles rapidly went up to 90∘C. The loading rate of VP16 was as high as 68%, the release rate reached 87% within 280[Formula: see text]min under microwave irradiation. Therefore, the functionalized (Fe3O4/nGO)@mSiO2/GQDs nanoparticles will have potential application for clinical treatment as drug delivery system.

scholarly journals Recycling Oxacillin Residues from Environmental Waste into Graphene Quantum Dots

2019 ◽  
Vol 5 (4) ◽  
pp. 68 ◽  
Author(s):  
Soriano ◽  
Cárdenas
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Fluorescence Emission ◽  
Waste Recycling ◽  
Primary Amines ◽  
Beta Lactam ◽  
Emerging Pollutant ◽  
Lactam Antibiotic ◽  
Potential Applications ◽  
Ir And Raman

Of great concern are the residual antibiotics from dirt that can be found in farm soil and wastewater. This kind of emerging pollutant into engineered nanomaterials is riveting. This work proposes the elimination and transformation of a beta-lactam antibiotic, oxacillin, from environmental waste to graphene quantum dots (GQDs). Two protocols were followed in which the use of ethylenediamine (EDA) in the transformation leads to GQDs with excellent optical properties. Therefore, two types of GQDs were synthesized in a Teflon-lined stainless autoclave by a thermal procedure using oxacillin in the absence and presence of EDA. The ensuing e-GQDs from oxacillin and EDA display a stronger fluorescence emission in comparison to those synthesized without EDA (o-GQDs). The combination of Kaiser test analyses, infrared (IR) and Raman measurements revealed the presence of oxygen-containing groups and primary amines at the edges of the graphitic nanolayer for e-GQDs. This straightforward strategy brings hope and opens a new interest in waste recycling by means of extracting residual contaminants from the environment for their further transformation into adequate non-toxic graphitic nanomaterials with potential applications.

One-Step Preparation of Green Fluorescent Graphene Quantum Dots from Petroleum Asphalt

2017 ◽  
Vol 45 ◽  
pp. 76-83 ◽  
Author(s):  
Pin Hui Zhao ◽  
Yi Luo ◽  
Ling Yun Kong
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Green Light ◽  
Average Diameter ◽  
Chemical Oxidation ◽  
Fluorescent Properties ◽  
Petroleum Asphalt ◽  
One Step ◽  
Bright Green ◽  
Green Fluorescent

Inherently benefiting from the natural nanosize graphene-structure in raw asphalt material. Asphalt-derived graphene quantum dots ( GQDs ) are prepared through, a facile route, one-step chemical oxidation of cheap petroleum asphalt. The as-prepared GQD sample may be well dissolved in water with a good homogeneous size at an average diameter of 2.44 nm, luminescing bright green light by excitation of 365 nm with a high quantum yield up to 16.13%. Furthermore, they are much smaller and thinner than most of the reported GQDs, presenting excellent fluorescent properties, such as excitation-tuned photoluminescence and good resistance to photobleaching. They are much smaller and thinner than most of the reported GQDs

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