Highly-dispersed copper microparticles on the active gold substrate as an amperometric sensor for glucose

Non-enzymatic glucose sensor with electrodeposited silver/carbon nanotubes composite electrode

Diabetes mellitus is a debilitating disease that affects each and every organ of human body. Hence it is important to continuously monitor the glucose level throughout the day and night. Glucose sensors are in great demand due to a rapid increase in diabetic community. A strategy has been implemented here to fabricate silver nanoparticles (AgNPs) with the support of functionalized carbon nanotubes (f-CNTs). Silver/carbon nanotubes (Ag/CNTs) nanocomposite electrode have been prepared by electrochemical process on Fluorine doped tin oxide (FTO) glass, by varying silver (Ag) concentrations for non-enzymatic glucose sensor. The variable Ag concentration in the morphology of Ag/CNTs nanocomposite has influenced the electrical conductivity, oxidation and reduction potential and electrochemical activity of glucose. Highest current density and good electrocatalytic activity for electrodes are obtained at 70 mM concentration of silver in Ag/CNTs composite. The present study indicates that the Ag/CNTs electrode is a possible substitute of the expensive glassy carbon electrode for enzyme-free glucose sensors.

Biosensors Incorporating Bimetallic Nanoparticles

This article presents a review of electrochemical bio-sensing for target analytes based on the use of electrocatalytic bimetallic nanoparticles (NPs), which can improve both the sensitivity and selectivity of biosensors. The review moves quickly from an introduction to the field of bio-sensing, to the importance of biosensors in today's society, the nature of the electrochemical methods employed and the attendant problems encountered. The role of electrocatalysts is introduced with reference to the three generations of biosensors. The contributions made by previous workers using bimetallic constructs, grouped by target analyte, are then examined in detail; following which, the synthesis and characterization of the catalytic particles is examined prior to a summary of the current state of endeavor. Finally, some perspectives for the future of bimetallic NPs in biosensors are given.

Facile preparation of a highly sensitive nonenzymatic glucose sensor based on multi-walled carbon nanotubes decorated with electrodeposited metals

Preparation of Ni/CuAg/MWCNT hybrid composite modified electrode: (a) bare, (b) MWCNT, (c) CuAg/MWCNT, and (d) Ni/CuAg/MWCNT modified electrodes.

A novel non-enzymatic glucose sensor based on Cu nanoparticle modified graphene sheets electrode

A novel, stable and sensitive non-enzymatic glucose sensor was developed by potentiostatically electrodepositing metallic Cu nanoparticles on graphene sheets. The electrochemical performance of the Cu-graphene sheets electrode for detection of glucose was investigated by cyclic voltammetry and chronamperometry. The Cu-graphene sheets electrode displayed a synergistic effect of copper nanoparticles and graphene sheets towards the oxidation of glucose in alkaline solution, showing higher oxidation current and negative shift in peak potential. At detection potential of 500 mV, the Cu-graphene electrode sensor presented a wide linear range up to 4.5mM glucose with a detection limit of 0.5 μM (signal/noise=3). In addition, the sensor responds very quickly (<2s) with addition of glucose. Furthermore, the Cu-graphene sheets electrode exhibits high stability and selectivity to glucose, and the poisoning by chloride ion as well as interference from the oxidation of common interfering species (ascorbic, dopamine, uric acid and carbohydrate) are effectively avoided. The Cu-graphene sheets electrode allows highly selective and sensitive, stable and fast amperometric sensing of glucose, which is promising for the development of non-enzymatic glucose sensor.

A sensitive nonenzymatic glucose sensor in alkaline media with a copper nanocluster/multiwall carbon nanotube-modified glassy carbon electrode

Copper (Cu) nanoclusters were electrochemically deposited on the film of a Nafion-solubilized multiwall carbon nanotube (CNTs)-modified glassy carbon electrode (CNTs-GCE), which fabricated a Cu-CNTs composite sensor (Cu-CNTs-GCE) to detect glucose with nonenzyme. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used for the characterization of the distribution of the Cu nanoclusters on the CNTs matrix. The composite of the Cu-CNTs was investigated by the electrochemical characterization of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The preliminary study shows that the nonenzymatic sensor has synergistic electrocatalytic activity to the oxidation of glucose in alkaline media. A well applicable sensor was constructed to use for the analysis of the glucose in real blood serum samples due to the large number of electrons taking part in the oxidation process, the high apparent kinetic rate constant, and the stable operation of the electrode. The linear range for the detection of the glucose is 7.0 x 10(-7) to 3.5 x 10(-3) M with a high sensitivity of 17.76 microA mM(-1), a low detection limit of 2.1 x 10(-7) M, and a fast response time of within 5s. Experiment results also showed that the sensor has good reproducibility and long-term stability and is interference free.

Metallic Nanoparticle−Carbon Nanotube Composites for Electrochemical Determination of Explosive Nitroaromatic Compounds

Metal nanoparticles (Pt, Au, or Cu) together with multiwalled and single-walled carbon nanotubes (MWCNT and SWCNT) solubilized in Nafion have been used to form nanocomposites for electrochemical detection of trinitrotoluene (TNT) and several other nitroaromatics. Electrochemical and surface characterization by cyclic voltammetry, AFM, TEM, SEM, and Raman spectroscopy confirmed the presence of metal nanoparticles on CNTs. Among various combinations tested, the most synergistic signal effect was observed for the nanocomposite modified glassy carbon electrode (GC) containing Cu nanoparticles and SWCNT solubilized in Nafion. This combination provided the best sensitivity for detecting TNT and other nitroaromatic compounds. Adsorptive stripping voltammetry for TNT resulted in a detection limit of 1 ppb, with linearity up to 3 orders of magnitude. Selectivity toward the number and position of the nitro groups in different nitroaromatics was very reproducible and distinct. Reproducibility of the TNT signal was within 7% (n = 8) from one electrode preparation to another, and the response signal was stable (+/-3.8% at 95% confidence interval) for 40 repeated analyses with 10 min of preconditioning. The Cu-SWCNT-modified GC electrode was demonstrated for analysis of TNT in tap water, river water, and contaminated soil.

Electrochemical Biosensing Platforms Using Platinum Nanoparticles and Carbon Nanotubes

Platinum nanoparticles with a diameter of 2-3 nm were prepared and used in combination with single-wall carbon nanotubes (SWCNTs) for fabricating electrochemical sensors with remarkably improved sensitivity toward hydrogen peroxide. Nafion, a perfluorosulfonated polymer, was used to solubilize SWCNTs and also displayed strong interactions with Pt nanoparticles to form a network that connected Pt nanoparticles to the electrode surface. TEM and AFM micrographs illustrated the deposition of Pt nanoparticles on carbon nanotubes whereas cyclic voltammetry confirmed an electrical contact through SWCNTs between Pt nanoparticles and the glassy carbon (GC) or carbon fiber backing. With glucose oxidase (GOx) as an enzyme model, we constructed a GC or carbon fiber microelectrode-based biosensor that responds even more sensitively to glucose than the GC/GOx electrode modified by Pt nanoparticles or CNTs alone. The response time and detection limit (S/N = 3) of this biosensor was determined to be 3 s and 0.5 microM, respectively.

Determination of electroactive organic acids by anion-exchange chromatography using a copper modified electrode

An ion-chromatographic method combined with electrochemical detection at a copper-based chemically modified glassy carbon electrode (Cu-GC) has been shown to provide a simple analytical approach for the determination of some common organic acids in alkaline medium. Under the optimized isocratic chromatographic conditions (i.e. 0.1 M NaOH plus 80 mM CH3COONa), organic acids such as gallic, ascorbic, gluconic, lactobionic, galacturonic and glucuronic acid could be separated in less than 20 min. Under constant potential amperometric detection (i.e. 0.55 V vs. Ag-AgCl) the Cu-GC modified electrode allowed detection limits between 2 and 5 pmol for all investigated organic acids while the linear dynamic range spanned generally over three orders of magnitude. Examples of applications included the separation and quantitation of some common organic acids in vinegar, honey and tea samples, are given.