Graphene Quantum Dots Electrochemistry and Development of Ultrasensitive Enzymatic Glucose Sensor

AbstractGraphene quantum dots (GQDs) - zero-dimensional materials - are sheets of a few nanometers in lateral dimension and exhibit quantum confinement and edge site effects where sp2-bonded carbon nanocore surrounded with edged plane functional moieties is promising as advanced electroactive sensing platforms. In this work, GQDs are synthesized by solvothermal and hydrothermal techniques, with optimal size of 5 nm. Their potential in fundamental (direct electron transfer) and applied (enzymatic glucose biosensor) electrochemistry are demonstrated. Glucose oxidase (GOx) immobilized on glassy carbon (GC) electrodes modified with GQDs are investigated by means of cyclic voltammetry, differential pulse voltammetry, and amperometry. Well-defined quasi-reversible redox peaks observed under various electrochemical parameters helped to determine diffusion coefficient (D) and first-order electron transfer rate (kET). The cyclic voltammetry curves showed homogeneous ion transport for GQD with D ranging between 8.45 × 10−9 m2 s−1 and 3 × 10−8 m2 s−1 following GO < rGO < GQD < GQD (with FcMeOH as redox probe) < GOx/rGO < GOx/GO < HRP/GQDs < GOx/GQDs. The developed GOx-GQDs biosensor responds efficiently and linearly to the presence of glucose over concentrations ranging 10 μM and 3 mM with limit of detection 1.35 μM and sensitivity 0.00769 μA μM−1·cm−2 as compared with rGO (0.025 μA μM−1 cm−2, 4.16 μM) and GO (0.064 μA μM−1 cm−2, 4.82 μM) nanosheets. The high performance and stability of GQDs is attributed to sufficiently large surface-to-volume ratio, excellent biocompatibility, abundant hydrophilic edge site density, and partially hydrophobic planar sites that favors GOx adsorption on the electrode surface and versatile architectures to ensure rapid charge transfer and electron/ion conduction (<10 ms). We also carried out similar studies with other enzymatic protein biomolecules on electrode surfaces prepared from GQD precursors for electrochemical comparison, thus opening up potential sensing applications in medicine as well as bio-nanotechnology.

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Development of Graphene Quantum Dots-Based Optical Sensor for Toxic Metal Ion Detection

Sensors ◽

10.3390/s19183850 ◽

2019 ◽

Vol 19 (18) ◽

pp. 3850 ◽

Cited By ~ 14

Author(s):

Nur Ain Asyiqin Anas ◽

Yap Wing Fen ◽

Nur Alia Sheh Omar ◽

Wan Mohd Ebtisyam Mustaqim Mohd Daniyal ◽

Nur Syahira Md Ramdzan ◽

...

Keyword(s):

Quantum Dots ◽

Metal Ions ◽

Optical Sensors ◽

Metal Ion ◽

Limit Of Detection ◽

Graphene Quantum Dots ◽

Toxic Metal ◽

Human Beings ◽

Toxic Metal Ions ◽

Sensing Applications

About 71% of the Earth’s surface is covered with water. Human beings, animals, and plants need water in order to survive. Therefore, it is one of the most important substances that exist on Earth. However, most of the water resources nowadays are insufficiently clean, since they are contaminated with toxic metal ions due to the improper disposal of pollutants into water through industrial and agricultural activities. These toxic metal ions need to be detected as fast as possible so that the situation will not become more critical and cause more harm in the future. Since then, numerous sensing methods have been proposed, including chemical and optical sensors that aim to detect these toxic metal ions. All of the researchers compete with each other to build sensors with the lowest limit of detection and high sensitivity and selectivity. Graphene quantum dots (GQDs) have emerged as a highly potential sensing material to incorporate with the developed sensors due to the advantages of GQDs. Several recent studies showed that GQDs, functionalized GQDs, and their composites were able to enhance the optical detection of metal ions. The aim of this paper is to review the existing, latest, and updated studies on optical sensing applications of GQDs-based materials toward toxic metal ions and future developments of an excellent GQDs-based SPR sensor as an alternative toxic metal ion sensor.

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The electron-transfer based interaction between transition metal ions and photoluminescent graphene quantum dots (GQDs): A platform for metal ion sensing

Talanta ◽

10.1016/j.talanta.2013.08.055 ◽

2013 ◽

Vol 117 ◽

pp. 152-157 ◽

Cited By ~ 73

Author(s):

Hongduan Huang ◽

Lei Liao ◽

Xiao Xu ◽

Mingjian Zou ◽

Feng Liu ◽

...

Keyword(s):

Quantum Dots ◽

Electron Transfer ◽

Transition Metal ◽

Metal Ions ◽

Metal Ion ◽

Graphene Quantum Dots ◽

Transition Metal Ions ◽

Ion Sensing ◽

Metal Ion Sensing

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Conjugation of Carboxylated Graphene Quantum Dots with Cecropin P1 for Bacterial Biosensing Applications

10.26434/chemrxiv.12116175.v2 ◽

2020 ◽

Author(s):

Jonathan Bruce ◽

Jude Clapper

Keyword(s):

Quantum Dots ◽

Structural Modification ◽

Light Emission ◽

Limit Of Detection ◽

Graphene Quantum Dots ◽

Strong Light ◽

E Coli ◽

Cecropin P1 ◽

Compact Field ◽

Test Kit

Quantum dots have proven to be strong candidates for biosensing applications in recent years, due to their strong light emission properties and their ability to be modified with a variety of functional groups for the detection of different analytes. Here, we investigate the use of conjugated carboxylated graphene quantum dots (CGQDs) for the detection of E. coli, using a biosensing procedure that focuses on measuring changes in fluorescence quenching. We have also further developed this biosensing assay into a compact, field-deployable test kit focused on rapidly measuring changes in absorbance to determine bacterial concentration. Our CGQDs were conjugated with cecropin P1, a naturally-produced antibacterial peptide that facilitates the attachment of CGQDs to E. coli cells. We also confirm the structural modification of these conjugated CGQDs in addition to analyzing their optical characteristics. Our findings have the potential to be used in situations where rapid, reliable detection of bacteria in liquids, such as drinking water, is required, especially given our biosensor’s relatively low observed limit of detection (LOD).

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In Vitro Evaluation of Miniaturized Amperometric Enzyme Sensor Based on the Direct Electron Transfer Principle for Continuous Glucose Monitoring

Journal of Diabetes Science and Technology ◽

10.1177/19322968211070614 ◽

2022 ◽

pp. 193229682110706

Author(s):

Yutaro Inoue ◽

Yasuhide Kusaka ◽

Kotaro Shinozaki ◽

Inyoung Lee ◽

Koji Sode

Keyword(s):

Electron Transfer ◽

Continuous Glucose Monitoring ◽

Glucose Sensor ◽

Direct Electron Transfer ◽

Glucose Dehydrogenase ◽

Glucose Monitoring ◽

Reference Electrode ◽

Enzyme Sensor

Background: The bacterial derived flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase (FADGDH) is the most promising enzyme for the third-generation principle-based enzyme sensor for continuous glucose monitoring (CGM). Due to the ability of the enzyme to transfer electrons directly to the electrode, recognized as direct electron transfer (DET)-type FADGDH, although no investigation has been reported about DET-type FADGDH employed on a miniaturized integrated electrode. Methods: The miniaturized integrated electrode was formed by sputtering gold (Au) onto a flexible film with 0.1 mm in thickness and divided into 3 parts. After an insulation layer was laminated, 3 openings for a working electrode, a counter electrode and a reference electrode were formed by dry etching. A reagent mix containing 1.2 × 10−4 Unit of DET-type FADGDH and carbon particles was deposited. The long-term stability of sensor was evaluated by continuous operation, and its performance was also evaluated in the presence of acetaminophen and the change in oxygen partial pressure (pO2) level. Results: The amperometric response of the sensor showed a linear response to glucose concentration up to 500 mg/dL without significant change of the response over an 11-day continuous measurement. Moreover, the effect of acetaminophen and pO2 on the response were negligible. Conclusions: These results indicate the superb potential of the DET-type FADGDH-based sensor with the combination of a miniaturized integrated electrode. Thus, the described miniaturized DET-type glucose sensor for CGM will be a promising tool for effective glycemic control. This will be further investigated using an in vivo study.

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Electrochemical detection of white spot syndrome virus with a silicone rubber disposable electrode composed of graphene quantum dots and gold nanoparticle-embedded polyaniline nanowires

Journal of Nanobiotechnology ◽

10.1186/s12951-020-00712-4 ◽

2020 ◽

Vol 18 (1) ◽

Author(s):

Kenshin Takemura ◽

Jun Satoh ◽

Jirayu Boonyakida ◽

Sungjo Park ◽

Ankan Dutta Chowdhury ◽

...

Keyword(s):

Quantum Dots ◽

White Spot Syndrome Virus ◽

Graphene Quantum Dots ◽

High Sensitivity ◽

White Spot ◽

Sensing Matrix ◽

Disposable Electrode ◽

Sensing Applications ◽

Doped Graphene ◽

White Spot Syndrome

Abstract Background With the enormous increment of globalization and global warming, it is expected that the number of newly evolved infectious diseases will continue to increase. To prevent damage due to these infections, the development of a diagnostic method for detecting a virus with high sensitivity in a short time is highly desired. In this study, we have developed a disposable electrode with high-sensitivity and accuracy to evaluate its performances for several target viruses. Results Conductive silicon rubber (CSR) was used to fabricate a disposable sensing matrix composed of nitrogen and sulfur-co-doped graphene quantum dots (N,S-GQDs) and a gold-polyaniline nanocomposite (AuNP-PAni). A specific anti-white spot syndrome virus (WSSV) antibody was conjugated to the surface of this nanocomposite, which was successfully applied for the detection of WSSV over a wide linear range of concentration from 1.45 × 102 to 1.45 × 105 DNA copies/ml, with a detection limit as low as 48.4 DNA copies/ml. Conclusion The engineered sensor electrode can retain the detection activity up to 5 weeks, to confirm its long-term stability, required for disposable sensing applications. This is the first demonstration of the detection of WSSV by a nanofabricated sensing electrode with high sensitivity, selectivity, and stability, providing as a potential diagnostic tool to monitor WSSV in the aquaculture industry.

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