Facile fabrication of FeN nanoparticles/nitrogen-doped graphene core-shell hybrid and its use as a platform for NADH detection in human blood serum

Non-enzymatic biosensor based on F,S-doped carbon dots/copper nanoarchitecture applied in the simultaneous electrochemical determination of NADH, dopamine, and uric acid in plasma

This work presents the synthesis and characterization of an innovative F,S-doped carbon dots/CuONPs hybrid nanostructure obtained by a direct mixture between F,S-doped carbon dots obtained electrochemically and copper nitrate alcoholic solution. The hybrid nanostructures synthesized were characterized by absorption spectroscopy in the Ultraviolet region (UV-vis), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and different electrochemical techniques. The fluoride and sulfur-doped carbon dots/CuONPs nanostructures were used to prepare a non-enzymatic biosensor on a printed carbon electrode, exhibiting excellent electrocatalytic activity for the simultaneous determination of NADH, dopamine, and uric acid in the presence of ascorbic acid with a detection limit of 20, 80, and 400 nmol L-1, respectively. The non-enzymatic biosensors were also used to determine NADH, dopamine, and uric acid in plasma, and they did not suffer significant interference from each other.

Zinc nitride quantum dots as an efficient probe for simultaneous fluorescence detection of Cu2+ and Mn2+ ions in water samples

The exceptional ascending heights of graphene (carbon) and boron nitride nanostructures have invited scientists to explore metal nitride nanomaterials. Herein, Zn3N2 quantum dots (QDs) were prepared via a simple hydrothermal route from the reaction between zinc nitrate hexahydrate and ammonia solution that possess efficient strength towards sensing applications of metal ions (Cu2+ and Mn2+). The as-prepared Zn3N2 QDs show bright fluorescence, displaying an emission peak at 408 nm upon excitation at 320 nm, with a quantum yield (QY) of 29.56%. It was noticed that the fluorescence intensity of Zn3N2 QDs linearly decreases with the independent addition of Cu2+ and Mn2+ ions, displaying good linearity in the ranges 2.5-50 µM and 0.05-5 µM with detection limits of 21.77 nM and of 63.82 nM for Cu2+ and Mn2+ ions, respectively. The probe was successfully tested for quantifying Cu2+ and Mn2+ in real samples including river, canal, and tap water, providing good recoveries with a relative standard deviation  < 2%. Furthermore, the masking proposition can successfully eliminate the interference if the two metal ions exist together. It was found that thiourea is efficiently able to mask Cu2+ and selectively quenches Mn2+, and L-cysteine is able to halt the quenching potential of Mn2+ and is selectively able to sense Cu2+. The Zn3N2 QDs provide a simple way for the simultaneous detection of both Cu2+ and Mn2+ ions in environmental samples at low sample preparations requirements.

Tamarindus indica seed-shell nanoparticles‑silver nanoparticles-Ceratonia silique bean gum composite for copper-micro mesh grid electrode fabrication and its application for glucose detection in artificial salivary samples

This study used a new approach to fabricate a glucose detection system based on nano-engineered biomaterials. The fabrication steps included strategic synthesis, integration and stabilization of biological and metal nanoparticles in superabsorbent hydrogel gum matrix. The design of the high-performance electrochemical biosensor platform includes copper-micro mesh grid electrode modified with polymer phase comprising of silver nanoparticles surface coroneted with Ceratonia silique locust bean gum (LBG), Tamarindus indica seed-shell nanoparticles and glucose oxidase (GOx). Fundamental assessment of catalytic properties of the nanobiocomposite films on copper grid probe were performed by cyclic voltammetry, amperometry, differential pulse voltammetry. Probes showed good repeatability, reproducibility, selectivity, and long-term stability. The GOx was well-immobilized and stabilized by C. siliqua nano-matrix, with 85% and 98% activity retention when stored at different condiions for 6 month and 3 months, respectively. The fabricated grid-platform exhibited linear response in a wide range of glucose concentration, with detection limit of 1.0 nM (S/N = 3) and sensitivity 38.7 mA nM^-1 cm^-2. The bionanomaterial-based sensor was successfully applied for ultra-low glucose detection in artificial salivary samples. The designed sensor, perhaps with further modifications, has potential for the next generation of sensing platform in various biological fluids especially for non-invasive glucose detection for diabetic patients.

Graphene-based nano composites and their applications. A review

The purpose of the current review article is to present a comprehensive understanding regarding pros and cons of graphene related nanocomposites and to find ways in order to improve the performance of nanocomposites with new designs. Nanomaterials including GR are employed in industrial applications such as supercapacitors, biosensors, solar cells, and corrosion studies. The present article has been prepared in three main categories. In the first part, graphene types have been presented, as pristine graphene, graphene oxide and reduced graphene oxide. In the second part, nanocomposites with many graphene, inorganic and polymeric materials such as polymer/GR, activated carbon/GR, metal oxide/GR, metal/graphene and carbon fibre/GR have been investigated in more detail. In the third part, the focus in on the industrial applications of GR nanocomposite, including super capacitors, biosensors, solar cells, and corrosion protection studies.

Electrical Property of Graphene and Its Application to Electrochemical Biosensing

Graphene, a single atom thick layer of two-dimensional closely packed honeycomb carbon lattice, and its derivatives have attracted much attention in the field of biomedical, due to its unique physicochemical properties. The valuable physicochemical properties, such as high surface area, excellent electrical conductivity, remarkable biocompatibility and ease of surface functionalization have shown great potentials in the applications of graphene-based bioelectronics devices, including electrochemical biosensors for biomarker analysis. In this review, we will provide a selective overview of recent advances on synthesis methods of graphene and its derivatives, as well as its application to electrochemical biosensor development. We believe the topics discussed here are useful, and able to provide a guideline in the development of novel graphene and on graphene-like 2-dimensional (2D) materials based biosensors in the future.

A review on graphene-based nanocomposites for electrochemical and fluorescent biosensors

Biosensors with high sensitivity, selectivity and a low limit of detection, reaching nano/picomolar concentrations of biomolecules, are important to the medical sciences and healthcare industry for evaluating physiological and metabolic parameters.

Nitrogen-Doped Graphene-Encapsulated Nickel Cobalt Nitride as a Highly Sensitive and Selective Electrode for Glucose and Hydrogen Peroxide Sensing Applications

To explore a natural nonenzymatic electrode catalyst for highly sensitive and selective molecular detection for targeting biomolecules is a very challenging task. Metal nitrides have attracted huge interest as promising electrodes for glucose and hydrogen peroxide (H₂O₂) sensing applications due to their exceptional redox properties, superior electrical conductivity, and superb mechanical strength. However, the deprived electrochemical stability extremely limits the commercialization opportunities. Herein, novel nitrogen-doped graphene-encapsulated nickel cobalt nitride (Ni _xCo_{3- x}N/NG) core-shell nanostructures with a controllable molar ratio of Ni/Co are successfully fabricated and employed as highly sensitive and selective electrodes for glucose and H₂O₂ sensing applications. The highly sensitive and selective properties of the optimized core-shell NiCo₂N/NG electrode are because of the high synergistic effect of the NiCo₂N core and the NG shell, as evidenced by a superior glucose sensing performance with a short response time of <3 s, a wide linear range from 2.008 μM to 7.15 mM, an excellent sensitivity of 1803 μA mM^-1 cm^-2, and a low detection limit of 50 nM (S/N = 3). Furthermore, the core-shell NiCo₂N/NG electrode shows excellent H₂O₂ sensing performances with a short response time of ∼3 s, a wide detection range of 200 nM to 3.4985 mM, a high sensitivity of 2848.73 μA mM^-1 cm^-2, and ultra-low limit detection of 200 nM (S/N = 3). The NiCo₂N/NG sensor can also be employed for glucose and H₂O₂ detection in human blood serum, promising its application toward the determination of glucose and H₂O₂ in real samples.

Progress in utilisation of graphene for electrochemical biosensors

This review discusses recent graphene (GR) electrochemical biosensor for accurate detection of biomolecules, including glucose, hydrogen peroxide, dopamine, ascorbic acid, uric acid, nicotinamide adenine dinucleotide, DNA, metals and immunosensor through effective immobilization of enzymes, including glucose oxidase, horseradish peroxidase, and haemoglobin. GR-based biosensors exhibited remarkable performance with high sensitivities, wide linear detection ranges, low detection limits, and long-term stabilities. Future challenges for the field include miniaturising biosensors and simplifying mass production are discussed.

Multilayer sensing platform: gold nanoparticles/prussian blue decorated graphite paper for NADH and H2O2 detection

An exfoliated graphite paper based multilayer sensing platform was fabricated and applied for sensitive detection of NADH and H₂O₂.

Hierarchical 3D Cobalt-Doped Fe3 O4 Nanospheres@NG Hybrid as an Advanced Anode Material for High-Performance Asymmetric Supercapacitors

Hierarchical nanostructure, high electrical conductivity, extraordinary specific surface area, and unique porous architecture are essential properties in energy storage and conversion studies. A new type of hierarchical 3D cobalt encapsulated Fe₃ O₄ nanosphere is successfully developed on N-graphene sheet (Co-Fe₃ O₄ NS@NG) hybrid with unique nanostructure by simple, scalable, and efficient solvothermal technique. When applied as an electrode material for supercapacitors, hierarchical Co-Fe₃ O₄ NS@NG hybrid shows an ultrahigh specific capacitance (775 F g^-1 at a current density of 1 A g^-1 ) with exceptional rate capability (475 F g^-1 at current density of 50 A g^-1 ), and admirable cycling performance (97.1% capacitance retention after 10 000 cycles). Furthermore, the fabricated Co-Fe₃ O₄ NS@NG//CoMnO₃ @NG asymmetric supercapacitor (ASC) device exhibits a high energy density of 89.1 Wh kg^-1 at power density of 0.901 kW kg^-1 , and outstanding cycling performance (89.3% capacitance retention after 10 000 cycles). Such eminent electrochemical properties of the Co-Fe₃ O₄ NS@NG are due to the high electrical conductivity, ultrahigh surface area, and unique porous architecture. This research first proposes hierarchical Co-Fe₃ O₄ NS@NG hybrid as an ultrafast charge-discharge anode material for the ASC device, that holds great potential for the development of high-performance energy storage devices.

Highly sensitive amperometric biosensor for determination of NADH and ethanol based on Au-Ag nanoparticles/poly(L-Cysteine)/reduced graphene oxide nanocomposite

This work presents the fabrication of a novel nicotinamide adenine dinucleotide (NADH) sensor using gold-silver bimetallic nanoparticles (Au-AgNPs), poly(L-Cysteine) (P(L-Cys)) and electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE/Au-AgNPs/P(L-Cys)-ERGO). The composite electrode exhibited an excellent electrocatalytic response towards NADH at a low oxidation potential (+ 0.35V) and minimization of surface contamination due to the synergistic effects of the Au-AgNPs, polymer and ERGO. Under optimum conditions, modified sensors allowed the detection of NADH with a wide linear range from 0.083µM to 1.05mM with a low detection limit of 9.0nM (S/N = 3). Moreover, this modified electrode was also used as a sensitive ethanol biosensor, which was prepared with alcohol dehydrogenase (ADH) via glutaraldehyde, bovin serum albumin and nafion (Naf). There was a linear response for ethanol in the concentration range from 0.017 to 1.845mM with a low detection limit of 5.0µM (S/N = 3). The GCE/Au-AgNPs/P(L-Cys)-ERGO/ADH/Naf electrode can be successfully used for the determination of ethanol in different commercial beverages.

An Overview of Carbon Nanotubes and Graphene for Biosensing Applications

With the development of carbon nanomaterials in recent years, there has been an explosion of interests in using carbon nanotubes (CNTs) and graphene for developing new biosensors. It is believed that employing CNTs and graphene as sensor components can make sensors more reliable, accurate, and fast due to their remarkable properties. Depending on the types of target molecular, different strategies can be applied to design sensor device. This review article summarized the important progress in developing CNT- and graphene-based electrochemical biosensors, field-effect transistor biosensors, and optical biosensors. Although CNTs and graphene have led to some groundbreaking discoveries, challenges are still remained and the state-of-the-art sensors are far from a practical application. As a conclusion, future effort has to be made through an interdisciplinary platform, including materials science, biology, and electric engineering.

Al-Based porous coordination polymer derived nanoporous carbon for immobilization of glucose oxidase and its application in glucose/O2 biofuel cell and biosensor

Herein, we report the first example of using the Al-based porous coordination polymers (Al-PCP) as a template for preparation of nanoporous carbon through a two-step carbonized method.