Functionalized multi walled carbon nanotubes nano biocomposite film for the amperometric detection of L-cysteine.

The development of nano biocomposite film (f-MWCNTs-Au-GO(x)) for L-cysteine (LC) detection is proposed by using glassy carbon electrode (GCE). The proposed nano biocomposite film has been fabricated on ITO for scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. Next, the f-MWCNTs-Au-GO(x) nano biocomposite film modified GCE's surface was examined by scanning electrochemical microscopy (SECM). The proposed nano biocomposite film has been successfully applied for the detection of LC using cyclic voltammetry (CV) and amperometry. The f-MWCNTs-Au-GO(x) film modified GCE exhibited a linear response for LC detection in the lower and higher concentrations ranges of 2 to 42 x 10(-6), 0.1 to 1.08 x 10(-3) mol L(-1). Also, the proposed nano biocomposite film possesses high sensitivity and good repeatability for LC detection.

Detection of melamine in milk powder and human urine.

Detection of melamine has been developed by employing oxidized polycrystalline gold electrode (poly GE). The poly GE was directly utilized for the detection of melamine using differential pulse voltammetry (DPV) and impedimetry. Poly GE successfully showed the oxidation peak for melamine adsorption at 1.1 V is purely based on the detection of adsorption signals of melamine at the electrode surface. Furthermore, the melamine adsorbed poly GE surface has been studied using atomic force microscopy (AFM). Poly GE successfully detects the oxidation signals of melamine in the linear range of 0.05-1.31 ppm in laboratory samples. The proposed poly GE successfully detects the melamine signal (0.06-0.85 ppm) in tainted milk powder samples. It also exhibits two well-separated anodic oxidation peaks for urine and melamine in melamine-spiked human urine samples. Gas chromatography-mass spectrometry (GC-MS) was also employed for the successful detection of melamine in the above proposed real samples.

Palladium nanoparticles modified electrode for the selective detection of catecholamine neurotransmitters in presence of ascorbic acid.

Palladium (Pd) nanoparticles are directly fabricated on glassy carbon electrode (GCE) and indium tin oxide electrode (ITO) by simple electrochemical deposition process. The Pd nanoparticles modified ITO electrode surface has been studied in detail using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The electrodeposited nano Pd particles are found as spherical shaped in the size range of 39-78 nm. The X-ray diffraction (XRD) analysis reveals that the electrodeposited nano Pd film possesses the face centered cubic crystalline structure. This nano Pd film modified GCE effectively exhibits the electro oxidation signals for the detection of catecholamines epinephrine (EP), norepinephrine (NEP) and dopamine (DA). Especially, the proposed nano Pd film modified GCE successfully showed two well separated anodic oxidation peaks for the detection of catecholamines and ascorbic (AA) in mixture solution. The proposed nano Pd film modified electrode also retains the advantage of easy fabrication, high sensitivity and good repeatability. Finally, this type of nano Pd film modified electrode supports the selective detection of catecholamines in injection solutions.

Easy modification of glassy carbon electrode for simultaneous determination of ascorbic acid, dopamine and uric acid.

A glassy carbon electrode (GCE) has been modified by electrochemical oxidation in mild acidic media (0.1 mol l(-1) H(2)SO(4)) and could be applied for individual and simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Oxidized GCE shows a single redox couple (E(0)'=-2.5 mV) which is based on the formation functional groups during the electrochemical pretreatment process. Proposed GCE successfully decreases the over potentials for the oxidation process of these species (AA, DA and UA) comparing with bare GCE. The oxidized GCE has its own simplicity, stability, high sensitivity and possesses the potential for simultaneous determination of AA, DA and UA.

Recent Updates of DNA Incorporated in Carbon Nanotubes and Nanoparticles for Electrochemical Sensors and Biosensors.

Innovations in the field of electrochemical sensors and biosensors are of much importance nowadays. These devices are designed with probes and micro electrodes. The miniaturized designs of these sensors allow analyses of materials without damaging the samples. Some of these sensors are also useful for real time analysis within the host system, so these sensors are considered to be more advantageous than other types of sensors. The active sensing materials used in these types of sensors can be any material that acts as a catalyst for the oxidation or reduction of particular analyte or set of analytes. Among various kinds of sensing materials, deoxyribonucleic acid (DNA), carbon nanotubes (CNTs) and nanoparticles have received considerable attraction in recent years. DNA is one of the classes of natural polymers, which can interact with CNTs and nanoparticles to form new types of composite materials. These composite materials have also been used as sensing materials for sensor applications. They have advantages in characteristics such as extraordinary low weight and multifunctional properties. In this article, advantages of DNA incorporated in CNT and nanoparticle hybrids for electrochemical sensors and biosensors are presented in detail, along with some key results noted from the literature.

Nanocomposite of functionalized multiwall carbon nanotubes with nafion, nano platinum, and nano gold biosensing film for simultaneous determination of ascorbic acid, epinephrine, and uric acid.

A unique bimetallic, nano platinum (Pt) with nano gold (Au) on nafion (NF) incorporated with functionalized multiwall carbon nanotubes (f-MWCNTs) composite film (f-MWCNTs-NF-PtAu) was developed by the potentiostatic method. The composite film exhibits promising efficient catalytic activity towards the oxidation of mixture of biochemical compounds and simultaneous measurement of ascorbate anion, epinephrine and urate anion in aqueous buffer solution (pH 6.75). Both, the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used for the measurement of electroanalytical properties of neurotransmitters by means of composite film modified electrodes. Well-separated voltammetric peaks were obtained for ascorbate, epinephrine and urate anions with the peak separations of 0.222 and 0.131V. The composite film can also be produced on gold and transparent semiconductor indium tin oxide electrodes for different kinds of studies such as electrochemical quartz crystal microbalance (EQCM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The incorporation of Pt and Au onto the f-MWCNTs-NF was revealed by the EQCM technique and the morphology of the film was studied using SEM, AFM and scanning electrochemical microscopy (SECM) techniques. Further, extensive studies were carried out using SECM for obtaining the surface current topographic images of composite film modified electrodes, and these indicated the presence of f-MWCNTs-NF-PtAu composite film on the electrode.

Preparation and characterization of PtAu hybrid film modified electrodes and their use in simultaneous determination of dopamine, ascorbic acid and uric acid.

A novel biosensor was fabricated by electrochemical deposition of platinum and gold nanoparticles (nanoAu) with l-Cysteine on glassy carbon electrode. It was found that the nanoAu particle size distribution range was (50-80 nm), and the platinum particle size range was (200-300 nm). The hybrid film could be produced on gold and transparent indium tin oxide electrodes for different kind of studies such as electrochemical quartz crystal microbalance (EQCM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) and electrochemical studies. The PtAu hybrid film was applied to the electro catalytic oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA) at pH 4.0 using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified electrode was quite effective not only to detect DA, AA and UA individually but also in simultaneous determination of these species in a mixture. The overlapping anodic peaks of DA, AA and UA were resolved into three well-defined voltammetric peaks in CV and DPV. The catalytic peak currents obtained from CV and DPV increased linearly with concentration. The relative standard deviation (% R.S.D., n=10) for AA, DA and UA were less than 2.0% and DA, AA and UA can be determined in the ranges of 0.103-1.65, 0.024-0.384 and 0.021-0.336 mM, respectively. In addition, the modified electrode also shows good sensitivity, and stability. Satisfactory results were achieved for the determination of DA, AA and UA in dopamine injection solution, vitamin C tablets and human urine samples.