Trace assay of insulin in a pharmacy drug with a paste electrode.

This paper describes the development of a voltammetric assay of insulin using a DNA immobilized onto a carbon nanotube paste electrode (CNPE), the peak potential of which was 0.2 V, vs. Ag/AgCl on the CNPE. The cyclic voltammetry (CV) and square-wave (SW) stripping voltammetry parameters of the optimized conditions were determined. Low analytical working ranges of 10-80 ugL-1 CV and 0.01-0.1 ngL-1 SW were attained. The precision of the insulin concentration of 0.01 ugL-1 was 0.14 (n = 15) RSD using the optimum conditions, in which the detection limit was 0.004 ngL-1 (6.9 × 10-12 M) (S/N = 3) using only an accumulation time of 400 s. The developed method was applied to determine insulin in a pharmacy drug from analytical-grade chemicals (from Aldrich).

Analysis of Staphylococcus aureus Molecules in Non-Treated Blood Using Mercury Immobilized Carbon Nanotube Sensor.

Staphylococcus aureus bacteria is a ubiquitous Gram-positive microorganism that causes infections related to the sudden infant death syndrome. Recently, basic detection methods depend on complicated PCR amplification, electric separation, spectric adsorption and other detection systems. However, in this study, simplified sensitive voltammetric skills are developed. To identify an effective diagnostic method for Staphylococcus aureus (SA), a voltammetric sensing probe was sought using mercury immobilized on a carbon nanotube sensor (MCN). The voltammetric MCN conditions were optimized through stripping and cyclic voltammetry. Diagnostic electrolyte was used on non-treated blood sera as an electrolyte solution. The optimum cyclic and stripping analytical working range was 0.5-4.0 mL (3 × 102~5 × 102 CFU/0.5 mL) SA. The statistic relative standard deviation of 0.1 mL SA was observed to be 0.0078 (n = 5). Using the optimum parameters, a diagnostic test was performed by the direct assay of SA in non-treated human blood and patient sera. Here, the developed results can be used for the direct assay of non-treated blood sera, organ monitoring, in-vivo diagnosis, and other assays requiring SA detection.

Detection of Toxic Heavy Metal, Co(II) Trace via Voltammetry with Semiconductor Microelectrodes.

The cobalt (Co(II)) ion is a main component of alloys and considered to be carcinogenic, especially due to the carcinogenic and toxicological effects in the aquatic environment. The toxic trace of the Co(II) detection was conducted using the infrared photodiode electrode (IPDE) using a working electrode, via the cyclic and square-wave anodic stripping voltammetry. The results indicated a sensitive oxidation peak current of Co(II) on the IPDE. Under the optimal conditions, the common-type glassy carbon, the metal platinum, the carbon paste, and the carbon fiber microelectrode were compared with the IPDE in the electrolyte using the standard Co(II). The IPDE was found to be far superior to the others.

Toxic Effect of Cadmium Assay in Contaminated Soil Earthworm Cell Using Modified Sensor.

A voltammetric toxic metal of cadmium detection was studied using a fluorine doped graphite pencil electrode (FPE) in a seawater electrolyte. In this study, square wave (SW) stripping and chronoamerometry were used for determination of Cd(II) in seawater. Affordable pencils and an auxiliary electrode were used as reference. All experiments in this study could be performed at reasonable cost by using graphite pencil. The application was performed on the tissue of contaminated soil earthworm. The results show that the method can be applicable for vegetables and in vivo fluid or medicinal diagnosis.

Diagnostic recognition of Escherichia coli septicemia in in vivo vascular blood.

A method of detecting Escherichia coli (EC) in in vivo blood with septicemia was sought using a handmade macro three-electrode (ME) system. Towards this end, an analytical ME probe was prepared using mercury immobilized on a carbon nanotube working electrode, and two graphite pencils were used as counter and reference electrodes instead of the expensive Ag/AgCl standard and Pt counter electrode. Under the optimum conditions, the cyclic potential was obtained at a 0.05 V anodic, then the square-wave stripping working range was obtained at 0.5-3.5 ml (3x10(2)~4x10(2)CFU/1ml) EC. Also under the optimum conditions, the statistic stability was examined in 1 ml EC 15(th) repeat anodic, with a relative standard deviation of RSD=0.98x10(-2). The developed method was applied to non treated blood, using only one drop. The patient blood with septicemia had a fast accumulation time (30 sec). A diagnostic detection limit of 0.06 ml EC was obtained. The recognition methods can be applied to in vivo vascular blood and real organic fluids, and can be used for poisoning control.

Diagnosis of trace toxic uranium ions in organic liver cell.

Uranium is toxic and radioactive traces of it can be found in natural water and soils. High concentrations of it in biological systems cause genetic disorders and diseases. For the in vivo diagnosis, micro and nano range detection limits are required. Here, an electrochemical assay for trace toxic uranium was searched using stripping voltammetry. Renewable and simplified graphite pencils electrode (PE) was used in a three-electrode cell system. Seawater was used instead of an electrolyte solution. This setup can yield good results and the detection limit was attained to be at 10 µgL(-1). The developed skill can be applied to organic liver cell.

Real-time Detection of Trace Copper in Brain and Kidney of Fish for Medical Diagnosis.

For the detection of trace copper to be used in medical diagnosis, a sensitive handmade carbon nanotube paste electrode (PE) was developed using voltammetry. Analytical optimized conditions were found at 0.05 V anodic peak current. In the same conditions, various common electrodes were compared using stripping voltammetry, and the PE was found to be more sharply sensitive than other common electrodes. At optimum conditions, the working ranges of 3~19 µgL(-1) were obtained. The relative standard deviation of 70.0 µgL(-1) was determined to be 0.117% (n = 15), and the detection limit (S/N) was found to be 0.6 µgL(-1) (9.4 × 10(-9) M). The results were applied in detecting copper traces in the kidney and the brain cells of fish.

Implementation of a biocircuit implants for neurotransmitter release during neuro-stimulation.

Neurotransmitter assay of epinephrine (EP) was sought using a modified carbon nanotube paste electrode (PE). Using optimum conditions, cyclic voltammetry (CV) and the square wave (SW) stripping voltammetric working ranges were attained to 10-100 mgL(-1) (CV) and 20-140 ngL(-1) (SW). The relative standard deviation of 0.0549 (n=15) was obtained at 20.0 mgL(-1) EP constant. Here, the analytical detection limit (S/N) was reached with 4.60 ngL(-1) (2.5×10(-11) molL(-1)) EP. The hand-made electrode was implanted into the in-vivo brain core of the animals and was used in chronoamperometric neurodetection. The results obtained are applicable in neurosensing, physiological control, and other neuroscience fields.

Detection of trace cobalt ions in in vivo plant cells using a voltammetric interlocking system.

This experiment was conducted to establish a system for detecting trace cobalt ions in water and plant tissues using a voltammetric in vivo sensor. Cyclic and stripping voltammetry was devised from hand-made, macro-type implantable three-electrode systems. The results reached micro and nano working ranges at 100 sec accumulation time. The statistical detection limit (S/N) was attained at 6.0 ng L(-1). For the in vivo application, direct assay of cobalt ions was carried out in Eichhornia crassipes (EC) deep tissue in real time with a preconcentration time of 100 s. Interfaced techniques can be interlocked with other control systems.

Detection of trace metal in distilled alcoholic drinks.

The presence of trace metal cadmium assay was investigated with a copper immobilized on a graphite carbon electrode (GPC), the modified property of which was determined with handheld voltammetric systems. Following the determination of the analytical stripping conditions of 0.45 V amplitude, 30 Hz frequency, -1.4 V initial potential, and 4.0 mV increment potential, only a 60-s experimental accumulation time was used. Using these conditions, the analytical detection limit approached the nano range. At this condition, the analytical application was performed on distilled alcoholic drinks for food manufacturing systems. This developed technique is faster and less costly than the common voltammetric and spectrophotometric methods.

Investigation of Water Safety in Non-treated Drinking Water with Trace Toxic Metals.

The trace toxic metal copper was assayed using mercury immobilized on a carbon nanotube electrode (MCW), with a graphite counter and a reference electrode. In this study, a macro-scale convection motor was interfaced with a MCW three-electrode system, in which a handmade MCW was optimized using cyclic- and square-wave stripping voltammetry. An analytical electrolyte for tap water was used instead of an expensive acid or base ionic solution. Under these conditions, optimum parameters were 0.09 V amplitude, 40 Hz frequency, 0.01 V incremental potential, and a 60-s accumulation time. A diagnostic working curve was obtained from 50.0 to 350 µg/L. At a constant Cu(II) concentration of 10.0 µg/L, the statistical relative standard deviation was 1.78% (RSD, n = 15), the analytical accumulation time was only 60 s, and the analytical detection limit approached 4.6 µg/L (signal/noise = 3). The results were applied to nontreated drinking water. The content of the analyzed copper using 9.0 and 4.0 µg/L standards were 8.68 µg/L and 3.96 µg/L; statistical values R(2) = 0.9987 and R(2) = 0.9534, respectively. This method is applicable to biological diagnostics or food surveys.

Diagnostic Assay of Trace Mercury in Muscle Cells.

An electrochemical diagnostic assay of a trace mercury was performed using stripping voltammetry, cyclic voltammetry and chronoamperometry. Three graphite pencil electrode systems were used as the working, auxiliary and reference electrodes. Fluorine immobilization was performed on the working electrode to improve the sensitive low detection limit. Clean seawater was used instead of an expensive electrolyte such as buffer solution, acid or base solution. The working ranges are better sensitive then observed for analogous method. The result was applied to the muscle cell of an earthworm that lived in soil contaminated with trace mercury.

Diagnosis of Dopamine in Brain Neuro Cell Using a Nafion-immobilized Carbon Electrode.

Nafion immobilized onto a graphite pencil carbon electrode (NPE) was used to a voltammetric assay of dopamine. The optimum analytical conditions of 150 Hz frequency, 150 mV amplitude, -2.0 V accumulation potential and 15 mV increment potential were obtained. The SW working range was attained to 0.0-80.0 ugL-1 and the CV range of 0.0-90 mgL-1. The statistic relative standard deviation of the 10.0mgL-1 dopamine was 0.041 (n = 20) at the optimum conditions. The analytical detection limit (S/N) was attained to 0.49 ugL-1 (2.62×10-9 M). The developed method was applied to diagnostic assay at the fish brain core and diluted nerve tissue within a pre-concentration time of 60 sec.

Detection of Helicobacter pylori DNA in preliminary stage gastric cancer cells.

AIMS: Helicobacter pylori (HP) DNA was assayed using a newly fabricated voltammetric handheld circuit equipped with an interfaced graphite pencil electrode (PE) sensor. METHODS: Under optimum analytical parameters, the square-wave (SW) stripping detection range attained was 0.1-0.7 mg/L. RESULTS: A relative standard deviation of 1.68% (RSD, n = 5) was observed at a 3.2 mg/L HP DNA within a 90 s accumulation time. Under these conditions, the analytical detection limit approached 0.07 mg/L. CONCLUSIONS: The developed methods can be applied to HP assays of preliminary stage gastric cancer patient tissues.

Toxicological investigation of radioactive uranium in seawater.

Trace uranium detection measurement was performed using DNA immobilized on a graphite pencil electrode (DGE). The developed probe was connected to the portable handheld voltammetric systems used for seawater analysis. The sensitive voltammogram was obtained within only 30 s accumulation time, and the anodic stripping working range was attained at 100~800 µg/l U and 10~50 µg/l. The statistic relative standard deviation of 30.0 mg/l with the 15(th) stripping was 0.2115. Here, toxicological and analytical application was performed in the seawater survey in a contaminated power plant controlling water. The results were found to be applicable for real-time toxicological assay for trace control.

Diagnostic Assay of Toxic Zinc in an Ex vivo Cell Using Voltammetry.

Voltammetric detection of the toxic Zn ion was investigated using a fluorine-doped graphite pencil electrode (FPE). It is notable from the study that pencils were used as reference and working electrodes. In all the experiments, a clean seawater electrolyte solution was used to yield good results. The analytical working range was attained to 10 µgL(-1). The optimized voltammetric condition was examined to maximize the effect of the detection of trace Zn. The developed sensor was applied to an earthworm's tissue cell. It was found that the methods can be applicable to in vivo fluid or agriculture soil and plant science.

Diagnosis of Helicobacter pylori bacterial infections using a voltammetric biosensor.

The voltammetric assay of Helicobacter pylori DNA was investigated using a bismuth-immobilized carbon nanotube electrode (BCNE). The analytical cyclic voltammetry (CV) peak potential was obtained at a 0.4V reduction scan, where the diagnostic optimum square-wave (SW) stripping working range was achieved at 0.72-7.92 µg/mL H. pylori DNA (11 points). A relative standard deviation of 1.68% (RSD, n=5) was obtained with 3.2 mg/mL H. pylori DNA using a 240 s accumulation time. Under optimum conditions, detection limit was 0.06 µg/mL. The developed sensors can be used for clinical application in the 15th doubted human gastric tissues, since the patient's peak current increased a hundred times more than the negative healthy tissue did. The sensing time obtained was only two minutes, and the process was simpler compared to common PCR amplification and electrophoresis photometric detection systems.

Diagnostic assay of trace lead in an ex vivo tissue using a combination electrode.

A voltametric diagnosis of trace lead was performed using macro type combination sensors of fluorine-doped graphite pencil electrodes (FPE). Two pencils were used as the reference and auxiliary instead of expensive Ag/AgCl standards and Pt counters. Under optimized conditions, a square wave (SW) stripping working curve was attained at 10-70 mg/L and a micro range of 10-70 µg/L. The developed sensor was not only inexpensive but also had a fast (90-s) accumulation time. An analytical detection limit of 10 µg/L was obtained. The results were applied to an ex vivo tissue and an artificial turf.

Diagnostic assay of carcinoembryonic antigen tumor markers using a fluorine immobilized biosensor with handmade voltammetric circuit.

The tumor marker carcinoembryonic antigen (CEA) was investigated using a graphite pencil electrode (PE) and fluorine immobilized onto a graphite pencil carbon electrode (FPE). The optimum diagnostic conditions for square wave (SW) stripping voltammetry and cyclic voltammetry were searched. The voltammograms indicated three other detection ranges of 0.4-1.6 µg/l cyclic voltammetry (PE) seven points, 0.2-1.2 µg/l SW (PE) cathodic six points, and better sensitive ranges of 0.05-0.45 µg/l SW (FPE). These were obtained within a diagnostic accumulation time of 120 s in 0.1 mol/l ammonium phosphate electrolyte solution of pH 5.0. Under optimum SW conditions, the detection limit (S/N) approached 0.08 µg/l CEA, and the relative standard deviation at 10 mg/l CEA was 0.074% in 15 measurements. The proposed method can be applied in tumor assay using cancer patient urine.

Radioactive uranium measurement in vivo using a handheld interfaced analyzer.

A trace uranium (U) detection method was developed with a handheld voltammetric analyzer that was the size of a mobile phone, with working sensors made of simple graphite pencil electrode (PE). The optimum stripping voltammetric conditions were sought, and the following results were obtained: 0.0 to 0.08 ng/L working ranges and a statistically relative standard deviation of 1.78% (RSD; n=15) at a 10.0 microg/L U spike. The experiment accumulation time used was only 150 s. Under this condition, the diagnostic detection limit approached 0.007 ng/L. The method was applied to soil of a natural rock in a radioactive mineralogy site. Earthworms that resided at this site were assayed. The method was found to be applicable in biological diagnosis or in real-time in vivo survey.