Showing papers in "Electroanalysis in 2013"
TL;DR: This article reviews recent advances and developments in the field of wearable sensors with emphasis on a subclass of these devices that are able to perform highly-sensitive electrochemical analysis, and identifies potential implications of this new sensing paradigm in the healthcare, fitness, security, and environmental monitoring domains.
Abstract: This article reviews recent advances and developments in the field of wearable sensors with emphasis on a subclass of these devices that are able to perform highly-sensitive electrochemical analysis Recent insights into novel fabrication methodologies and electrochemical techniques have resulted in the demonstration of chemical sensors able to augment conventional physical measurements (ie heart rate, EEG, ECG, etc), thereby providing added dimensions of rich, analytical information to the wearer in a timely manner Wearable electrochemical sensors have been integrated onto both textile materials and directly on the epidermis for various monitoring applications owing to their unique ability to process chemical analytes in a non-invasive and non-obtrusive fashion In this manner, multi-analyte detection can easily be performed, in real time, in order to ascertain the overall physiological health of the wearer or to identify potential offenders in their environment Of profound importance is the development of an understanding of the impact of mechanical strain on textile- and epidermal (tattoo)-based sensors and their failure mechanisms as well as the compatibility of the substrate employed in the fabrication process We conclude this review with a retrospective outlook of the field and identify potential implications of this new sensing paradigm in the healthcare, fitness, security, and environmental monitoring domains With continued innovation and detailed attention to core challenges, it is expected that wearable electrochemical sensors will play a pivotal role in the emergent body sensor networks arena
595 citations
TL;DR: In this paper, a review on the recent progress of square-wave voltammetry is presented, covering the period of the last five years, addressing the new theoretical development of the technique as well as its application for mechanistic purposes, electrode kinetic measurements, biochemical and analytical applications.
Abstract: A review on the recent progress of square-wave voltammetry is presented, covering the period of the last five years. The review addresses the new theoretical development of the technique as well as its application for mechanistic purposes, electrode kinetic measurements, biochemical and analytical applications. Besides, a few novel methodological modifications are proposed that might expand the scope and application of the technique.
172 citations
TL;DR: Biocatalytic electrodes made of buckypaper were modified with PQQ-dependent glucose dehydrogenase on the anode and with laccases on the cathode for implanted biofuel cell operation and achieved steady-state open circuitry voltage and short circuitry current in the in vivo operatingBiofuel cell.
Abstract: Biocatalytic electrodes made of buckypaper were modified with PQQ-dependent glucose dehydrogenase on the anode and with laccase on the cathode. The enzyme modified electrodes were assembled in a biofuel cell which was first characterized in human serum solution and then the electrodes were placed onto exposed rat cremaster tissue. Glucose and oxygen dissolved in blood were used as the fuel and oxidizer, respectively, for the implanted biofuel cell operation. The steady-state open circuitry voltage of 140±30 mV and short circuitry current of 10±3 µA (current density ca. 5 µA cm−2 based on the geometrical electrode area of 2 cm2) were achieved in the in vivo operating biofuel cell. Future applications of implanted biofuel cells for powering of biomedical and sensor devices are discussed.
123 citations
TL;DR: In this article, a novel nanocomposite has been synthesized by molybdenum disulfide (MoS2) nanosheets and gold nanoparticles (AuNPs) via a microwave-assisted hydrothermal method, which possesses the specific features of both MoS2 and AuNPs.
Abstract: Herein, a novel nanocomposite has been synthesized by molybdenum disulfide (MoS2) nanosheets and gold nanoparticles (AuNPs) via a microwave-assisted hydrothermal method, which possesses the specific features of both MoS2 and AuNPs. The AuNPs@MoS2 nanocomposite modified electrode exhibits excellent electrocatalytic activity toward dopamine (DA). Its oxidation peak current shows a linear dependence over the DA concentration in the range from 0.1 to 200 µM, with a detection limit of 80 nM (S/N=3). More importantly, the AuNPs@MoS2-based sensor can detect DA in the presence of a large excess of ascorbic acid. The AuNPs@MoS2-based sensor shows good sensitivity, reproducibility and selectivity, suggesting that the AuNPs@MoS2 nanocomposite is a promising candidate in electrochemical sensing and other electrocatalytic applications.
107 citations
TL;DR: In this paper, the reduced graphene oxide-nickel nanoparticles composite (RGO-NiNPs) was synthesized using both electrochemical reduction and electrodeposition methods for electrochemical sensing.
Abstract: Electrochemical reduction and electrodeposition are two effective methods for the preparation of new nanomaterials for electrochemical sensing. In this work, the reduced graphene oxide-nickel nanoparticles composite (RGO-NiNPs) was synthesized using both methods mentioned above. The fabrication process was simple and easily performed. Then, the RGO-NiNPs composite was characterized by SEM, EDS, and XRD. Furthermore, for the strong catalytic ability of the high-valent oxyhydroxide species (NiOOH) formed in alkaline media, the composite was used as the matrix for nonenzymatic detection of glucose. Comparing with NiNPs modified glassy carbon electrode (NiNPs/GCE), the RGO-NiNPs/GCE showed better sensitivity and stability. A low detection limit of 0.1 mu M with a wide linear range from 2 mu M to 2.1mM (R=0.996) was obtained.
98 citations
TL;DR: In this article, some simple approaches are briefly reviewed, based on some well-known books and guidelines, which allow a better estimation of the most frequently reported figures of merit, but the results would benefit from an easier acceptance by the scientific community.
Abstract: A description of the performances of new electrochemical sensors is important for evaluating their novelty and potential applicability to the analysis of real samples. However, it was noticed that quite often some figures of merit were ill-defined or reported in an inadequate format. Based on some well-known books and guidelines, some simple approaches are briefly reviewed which allow a better estimation of the most frequently reported figures of merit. Adopting these approaches implies a certain increase of cost and time of the given investigations. But the results would benefit from an easier acceptance by the scientific community.
72 citations
TL;DR: In this paper, a simple method is described to discriminate between analytes comigrating under on-plate separation conditions, whose electrochemical behavior displays different reversible characters, based on the use of dual electrode detectors pencil-drawn at the end of paper-based fluidic channels defined by hydrophobic barriers.
Abstract: A simple method is described to discriminate between analytes comigrating under on-plate separation conditions, whose electrochemical behavior displays different reversible characters. It is based on the use of dual electrode detectors pencil-drawn at the end of paper-based fluidic channels defined by hydrophobic barriers. Simultaneous detection of comigrating species is achieved by applying to the upstream pencil-drawn working electrode a potential for the oxidation (or reduction) of both analytes, while to the downstream pencil-drawn working electrode a potential is imposed for the reverse process involving the product of the sole analyte undergoing a reversible enough electrochemical process. The performance of these inexpensive devices was preliminarily optimized by adopting hexacyanoferrate(II) as prototype species undergoing a reversible anodic process at carbon electrodes. They were then used as dual electrode detectors for thin-layer chromatographic runs conducted on paper-based microfluidic devices. Two types of synthetic solutions, one containing different contents of dopamine (DA) and ascorbic acid (AA) and the other of paracetamol (PA) and AA, were chosen as model samples. This choice was prompted us by the fact that in both cases these analytes comigrated under the adopted experimental conditions and required similar enough oxidation potentials. Nevertheless, DA and PA underwent reversible enough anodic processes while an irreversible electrochemical reaction is involved in the AA oxidation. Satisfactory results were found for both couples of target analytes, whose simultaneous detection was achieved within 230 s and was characterized by good enough repeatability and sensitivity. In particular, this approach appears to be well suited for the rapid and inexpensive assembling of electrochemical detectors for flow analysis systems.
71 citations
TL;DR: In this article, graphite electrodes modified by a thin DNA-imprinted polypyrrole layer, which was able to bind specific target-DNA, are used for electrochemical determination of target DNA by differential pulse voltammetry.
Abstract: In this study graphite electrodes modified by a thin DNA-imprinted polypyrrole layer, which was able to bind specific target-DNA, are reported. For this aim, electrochemical synthesis of polypyrrole was performed on a pencil graphite electrode by cyclic voltammetry (CV) or by potential pulse sequences (PPS). The modified electrode surface was used for electrochemical determination of target-DNA by differential pulse voltammetry. According to our best knowledge this is a first report on the application of DNA-imprinted polymer for the determination of target-DNA. The results showed that the molecularly imprinted polypyrrole (MIPPy) layer that formed on the carbon electrode surface was sensitive for target-DNA, while the nonimprinted polypyrrole layer was not sensitive to the same target-DNA. Comparison of electrodes modified using PPS and CV techniques is presented.
67 citations
TL;DR: In this paper, a photoelectrochemical (PEC) sensor is proposed to detect endocrine disruptor bisphenol A (BPA) based on vertically aligned TiO2 nanotubes (TiO2 NTs) with surface molecularly imprinted polypyrrole (PPy) for the first time.
Abstract: A novel and simple photoelectrochemical (PEC) sensor is proposed to detect endocrine disruptor bisphenol A (BPA) based on vertically aligned TiO2 nanotubes (TiO2 NTs) with surface molecularly imprinted polypyrrole (PPy) for the first time The developed PEC analytical method towards BPA successfully overcomes the high oxidation overvoltage required in sole electrochemical (EC) method, which may lead to electrochemical polymerization of BPA and accumulation of intermediate products and then bring the passivation of the electrode Under a very low potential (50 mV vs SCE), a highly sensitive PEC response for BPA is obtained in the linear range from 45 to 108 nM with a limit of detection (LOD) as low as 20 nM Simultaneously, by combining the surface molecularly imprinted polymer (MIP) technique with PEC method, specific recognition of BPA can be realized on the PEC sensor, even in coexisting systems containing 100-fold concentration of other substances with similar structures or chemical properties, such as hydroquinone, 1-naphthol or triphenylcarbino The PEC sensor also presents good applicability and high stability in real water samples The sensitive and selective recognition mechanisms are further discussed
65 citations
TL;DR: An electroanalytical method for the simultaneous determination of paracetamol (PAR), caffeine (CAF), and orphenadrine (ORPH) using the square-wave voltammetry (SWV) and a cathodically pretreated boron-doped diamond electrode was developed as mentioned in this paper.
Abstract: An electroanalytical method for the simultaneous determination of paracetamol (PAR), caffeine (CAF), and orphenadrine (ORPH) using the square-wave voltammetry (SWV) and a cathodically pretreated boron-doped diamond electrode was developed. The method exhibits linear responses to PAR, CAF, and ORPH in the concentration ranges 5.4×10−7–6.1×10−5 M, 7.8×10−7–3.5×10−5 M, and 7.8×10−7–3.5×10−5 M, respectively, with detection limits of 2.3×10−7 M, 9.6×10−8 M, and 8.4×10−8 M, respectively. The proposed method was successfully applied in the simultaneous determination of these analytes in pharmaceutical formulations.
64 citations
TL;DR: In this article, the electrochemical detection of hydrogen peroxide and nitrite, as important representatives of reactive reactive oxygen/nitrogen (ROS, RNS) species released during cellular oxidative bursts, is reported in microfluidic devices.
Abstract: The electrochemical detection of hydrogen peroxide and nitrite, as important representatives of cytotoxic reactive oxygen/nitrogen (ROS, RNS) species released during cellular oxidative bursts, is reported in microfluidic devices. Platinum-black coated platinum (Pt/Pt-black) electrodes were microfabricated and optimized to achieve optimal detection performances. In parallel, oxidation mechanisms of hydrogen peroxide and nitrite at these microelectrodes were investigated and electrode responses were compared to theoretical predictions based on convective mass transport at microchannel electrodes. In both cases, the active surface area of Pt/Pt-black electrodes allowed to avoid inhibition effect leading to long term stability in contrast to bare Pt electrodes. Such highly sensitive Pt/Pt-black electrodes allowed almost five decades of concentration range and detection limits down to 10 nM, a range suitable for detection of ROS and RNS released by a few cells.
TL;DR: In this paper, an electrochemical DNA biosensor, based on a dual signal amplified strategy by employing a polyaniline film and gold nanoparticles as a sensor platform and enzyme-linked as a label, for sensitive detection is presented.
Abstract: In this work, an electrochemical DNA biosensor, based on a dual signal amplified strategy by employing a polyaniline film and gold nanoparticles as a sensor platform and enzyme-linked as a label, for sensitive detection is presented. Firstly, polyaniline film and gold nanoparticles were progressively grown on graphite screen-printed electrode surface via electropolymerization and electrochemical deposition, respectively. The sensor was characterized by scanning electron microscopy (SEM), cyclic voltammetry and impedance measurements. The polyaniline-gold nanocomposite modified electrodes were firstly modified with a mixed monolayer of a 17-mer thiol-tethered DNA probe and a spacer thiol, 6-mercapto-1-hexanol (MCH). An enzyme-amplified detection scheme, based on the coupling of a streptavidin-alkaline phosphatase conjugate and biotinylated target sequences was then applied. The enzyme catalyzed the hydrolysis of the electroinactive α-naphthyl phosphate to α-naphthol; this product is electroactive and has been detected by means of differential pulse voltammetry. In this way, the sensor coupled the unique electrical properties of polyaniline and gold nanoparticles (high surface area, fast heterogeneous electron transfer, chemical stability, and ease of miniaturisation) and enzymatic amplification. A linear response was obtained over a concentration range (0.2–10 nM). A detection limit of 0.1 nM was achieved.
TL;DR: In this paper, an assessment of twenty years of strategies from a group dedicated to the electrochemical detection of nitric oxide NO in solution, for biological applications is presented, and a brief outlook into the future perspectives of the use of multi electrochemical array sensor is presented.
Abstract: We present an assessment of twenty years of strategies from our group dedicated to the electrochemical detection of nitric oxide NO in solution, for biological applications. We provide a full description of the electrochemical approaches and we summarize the significant research contributions towards the development of sensors. We emphasize the importance of understanding how to improve the performances of the sensors in terms of sensitivity and selectivity. A brief outlook into the future perspectives of the use of multi electrochemical array sensor is presented.
TL;DR: In this paper, two simple and sensitive approaches for CA 125 detection are presented by using antibody immobilized on poly-anthranilic acid modified graphite screen-printed electrodes with subsequent covalently monoclonal antibody anti-CA 125 immobilization.
Abstract: In this paper, two simple and sensitive approaches for CA 125 detection are presented by using antibody immobilized on poly-anthranilic acid modified graphite screen-printed electrodes. The first proposed approach is a label-free impedimetric immunosensor. The immunoassay is based on poly-anthranilic acid (PAA) modified graphite screen-printed electrodes with subsequent covalently monoclonal antibody anti-CA 125 immobilization. The modified screen-printed electrodes are used to capture the protein from the sample solutions. A curve calibration by electrochemical impedance spectroscopy (EIS) was obtained. The second approach is based on a sandwich format. The monoclonal anti-CA 125 antibodies immobilized on poly-anthranilic acid modified graphite screen-printed electrodes is used to capture the protein from the sample solution. The sandwich assay is then performed by adding secondary anti-CA 125 antibodies labeled with gold nanoparticles (AuNPs). The antibody-AuNPs captured onto immunosensor surface induced the silver deposition from a silver enhancer solution. The deposited AgNPs could be measured by anodic stripping analysis (ASV) in acid solution. A curve calibration by ASV was obtained. The experimental conditions were examined and were optimized using electrochemical impedance spectroscopy. The performance of both immunosensors in terms of sensitivity, reproducibility and selectivity were studied.
TL;DR: The results of this work show that Zn detection in serum is possible with smaller sample volumes and faster turnaround time as compared with the conventional spectroscopic methods.
Abstract: Zinc (Zn) homeostasis is required for a functional immune system. Critically ill patients often exhibit decreased Zn serum concentrations and could potentially benefit from Zn supplementation as a therapeutic strategy. However, the conventional approaches to monitoring Zn are time consuming and costly. This work reports on detection of Zn by anodic stripping voltammetry (ASV) on bismuth electrodes in a microfabricated electrochemical cell. The working potential window of the electrodeposited bismuth film electrode was investigated by cyclic voltammetry, while square wave ASV was used for measuring Zn in acetate buffer and blood serum. Conditions critical to sensing, such as preconcentration potential, preconcentration time, and buffer pH, were optimized for Zn detection. The sensor was successfully calibrated with pH 6 acetate buffer in the physiologically-relevant range of 5 μM to 50μM Zn and exhibited well-defined and highly repeatable peaks. The sensor was used to demonstrate measurement of Zn in blood serum digested in HCl. The results of this work show that Zn detection in serum is possible with smaller sample volumes (μL vs. μL) and faster turnaround time (hours vs. days) as compared with the conventional spectroscopic methods.
TL;DR: In this paper, a modified carbon electrode was used to facilitate and observe the electrocatalytic oxidation of coenzymes such as NADH, cysteine, and glutathione at different concentrations.
Abstract: A modified electrode was prepared using electrodeposition methods to immobilize caffeic acid (CAF) onto the surface of a glassy carbon electrode (GCE) to create a polymer suitable for biosensor development. The polymer film coverage of the surface bound species was further optimized using electrodeposition methods, thus increasing the surface coverage to ca. 10−9 mol cm−2. Using cyclic voltammetry, the modified carbon electrode was used to facilitate and observe the electrocatalytic oxidation of coenzymes such as NADH, cysteine, and glutathione at different concentrations. A calibration curve was determined in each case within the concentration range; 300 nM to 10 mM, with the limits of detection (LOD) of 246 µM, 99 µM, 2.2 µM for NADH, cysteine, and glutathione respectively.
TL;DR: An electrochemical aptasensor for ochratoxin A (OTA) detection has been developed on the base of a gold electrode covered with electropolymerized neutral red and silver nanoparticles obtained by chemical reduction with macrocyclic ligands bearing catechol fragments as mentioned in this paper.
Abstract: An electrochemical aptasensor for ochratoxin A (OTA) detection has been developed on the base of a gold electrode covered with electropolymerized neutral red and silver nanoparticles obtained by chemical reduction with macrocyclic ligands bearing catechol fragments. Thiolated aptamers against OTA were covalently attached to silver nanoparticles via AgS bonding. The interaction with OTA induced the conformational switch of the aptamer, which caused increase of the charge transfer resistance measured by EIS in the presence of ferricyanide ions. The LOD achieved (0.05 nM) was comparable to other electrochemical aptasensors employing sophisticated assembling technique and enzyme amplification of the signal. The aptasensor was validated in spiked beer samples. The recovery of the OTA determination was found to be 66.3 14.1 % for light beer and 64.3 1.8 % for dark beer.
TL;DR: A novel potentiometric cholesterol bios sensor was fabricated by immobilization of cholesterol oxidase into stabilized lipid films using zinc oxide (ZnO) nanowalls as measuring electrode resulting in a sensitive, selective, stable and reproducible cholesterol biosensor.
Abstract: A novel potentiometric cholesterol biosensor was fabricated by immobilization of cholesterol oxidase into stabilized lipid films using zinc oxide (ZnO) nanowalls as measuring electrode. Cholesterol oxidase was incorporated into the lipid film prior polymerization on the surface of ZnO nanowalls resulting in a sensitive, selective, stable and reproducible cholesterol biosensor. The potentiometric response was 57 mV/ decade concentration. The sensor response had no interferences by normal concentrations of ascorbic acid, glucose, and urea, proteins and lipids. The present biosensor could be implanted in the human body because of the biocompatibility of the lipid film.
TL;DR: In this article, branched polyethyleneimine (PEI) was covalently linked to carboxylic acid functionalized graphene (GO-COOH) to form GO-COH/PEI composites.
Abstract: In this study, branched polyethyleneimine (PEI) was covalently linked to carboxylic acid functionalized graphene (GO-COOH) to form GO-COOH/PEI composites. Transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectra and thermogravimetric analysis were used to characterize the obtained composites. Electrochemical measurements indicated that the modification of the composites on the electrode could efficiently enhance the voltammetric response, suggesting the potential application for making electrochemical sensors. Moreover, our results also indicated that the electrocatalytic oxidation of ammonia could be observed on the GO-COOH/PEI composites modified glassy carbon electrode. Consequently, our observations demonstrated that GO-COOH/PEI composites were excellent materials for electrochemical sensing.
TL;DR: In this paper, the authors reported the ultrasensitive and simultaneous determination of Zn2+, Cd2+ and Pb2+ on a multiwalled carbon nanotubes and Nafion composite modified screen-printed electrodes with in situ plated bismuth film.
Abstract: Screen-printed electrodes (SPEs) are cheap and disposable. But their application for heavy metal detection is limited due to the low sensitivity and poor selectivity. Here we report the ultrasensitive and simultaneous determination of Zn2+, Cd2+ and Pb2+ on a multiwalled carbon nanotubes and Nafion composite modified SPE with in situ plated bismuth film (MWCNTs/NA/Bi/SPE). The linear curves range from 0.5–100 µg L−1 for Zn2+ and 0.5–80 µg L−1 for Cd2+. Uniquely, the linear curve for Pb2+ ranges from 0.05–100 µg L−1 with a detection limit of 0.01 µg L−1. The practical application was verified in real samples with satisfactory results.
TL;DR: A single compartment biofuel cell based on an anode and a cathode powered by the same fuel glucose is reported, and glucose oxidase from Aspergillus niger was applied as a glucose consuming biocatalyst for both anodes and cathode of the BFC.
Abstract: A single compartment biofuel cell (BFC) based on an anode and a cathode powered by the same fuel glucose is reported. Glucose oxidase (GOx) from Aspergillus niger was applied as a glucose consuming biocatalyst for both anode and cathode of the BFC. The 5-amino-1,10-phenanthroline modified graphite rod electrode (GRE) with cross-linked GOx was used as the bioanode, and the GRE with co-immobilised horseradish peroxidase and GOx was exploited as the biocathode of the BFC. The open-circuit voltage of the designed BFC exceeded 450 mV and a maximal power density of 3.5 µW/cm2 was registered at a cell voltage of 300 mV.
TL;DR: In this article, a gold nanoparticle and graphene nanosheet (GN) modified glassy carbon electrode (GCE) was proposed as voltammetric sensor for detecting caffeic acid.
Abstract: A gold nanoparticle (AuNP) and graphene nanosheet (GN) modified glassy carbon electrode (GCE) is proposed as voltammetric sensor for caffeic acid assay. The sensor exhibits a surface-confined and reversible process for oxidation of caffeic acid revealed by cyclic voltammetry. The results show more favorable electron transfer kinetics than the bare GCE. The linear response of the sensor is from 5×10−7 to 5×10−5 M with a detection limit of 5×10−8 M (S/N=3). The AuNP/GN nanocomposite shows more favorable electrochemical activity and should be a kind of more robust and advanced functional material, which provides a promising platform for electrochemical sensors and biosensors. The method was successfully applied to detect caffeic acid in pharmaceutical tablets with satisfactory results.
TL;DR: In this paper, a molecularly imprinted co-polymer (MIP) was designed for the sensitive detection of streptomycin (STR) in food using enzymes as signal amplification.
Abstract: We have designed a new molecularly imprinted co-polymer (MIP) for the sensitive detection of streptomycin (STR) in food using enzymes as signal amplification. The MIP was fabricated via co-polymerization of aniline and o-phenylenediamine on gold substrate in the presence of STR as template. The assay is based on competitive binding of free STR and glucose oxidase-labeled STR (GOx-STR) to the imprinters on the MIP. On addition of glucose, hydrogen peroxide is formed that is detected by differential pulse voltammetry. Under optimal conditions, the decrease of the catalytic current is proportional to the STR concentration in the range from 0.01 to 10 ng mL−1, with a detection limit (LOD) of 7.0 pg mL−1 STR (at 3sB). Intra- and inter-assay coefficients of variation (CVs) are<10.5 %. The system was further validated and evaluated with STR-spiked samples including honey and milk, and the recovery was between 82 and 124.2 %.
TL;DR: Advances in electrochemical detection of Gunshot Residue indicate great promise for investigating firearm-related crimes, and bring significant changes to the detection of GSR making electroanalysis a powerful tool for decentralized forensic analysis.
Abstract: Current demands for detection of Gunshot Residue (GSR) require a reliable and rapid decentralized detection system with high sensitivity and specificity. This article reviews the use of electrochemical devices for GSR detection over the last 35 years and highlights recent advances associated with the demands of GSR field detection such as portability, speed, cost and power. Anodic stripping voltammetry (ASV) has been widely implemented for the detection of the metallic components of GSR at a variety of working electrodes. Efforts toward the detection of the organic components of GSR have also been reported using cyclic- and square-wave voltammetry. The simultaneous detection of both organic and inorganic GSR constituents has recently been examined to increase the overall information content in a single voltammetric scan. As well as this, exploitation of screen-printing fabrication allows replacement of conventional electrochemical cells with easy-to-use sensor strips Sampling methods for electrochemical GSR analysis are also advancing from acid washes or swabs to simpler abrasive methods which integrate sampling and analysis obviating the need for intermediate processing steps. The latest direction of electrochemical detection of GSR involves chemometric treatment to evaluate data allowing for more objective conclusions and increasing the automation of the system. These advances indicate great promise for investigating firearm-related crimes, and bring significant changes to the detection of GSR making electroanalysis a powerful tool for decentralized forensic analysis.
TL;DR: The authors presentado al 14th International Conference on Electroanalysis (ESEAC 2012) celebrado en Eslovenia., et al. presentado el 14th EESAC 2012.
Abstract: Trabajo presentado al 14th International Conference on Electroanalysis (ESEAC 2012) celebrado en Eslovenia.-- et al.
TL;DR: In this paper, a simple electrochemical method was developed to determine metronidazole based on β-cyclodextrin-functionalized gold nanoparticles/poly(L-cysteine) modified glassy carbon electrode (β-CD-GNPs/poly (L-cys)/GCE).
Abstract: A simple electrochemical method was developed to determine metronidazole based on β-cyclodextrin-functionalized gold nanoparticles/poly(L-cysteine) modified glassy carbon electrode (β-CD-GNPs/poly(L-cys)/GCE). The electropolymerized film of poly(L-cys) provides a stable matrix for the fabrication of a sensing interface. β-CD-GNPs can form inclusion complexes with metronidazole and act as a modifier with catalytic function. The modified electrode exhibited excellent electrocatalytic activity towards metronidazole. The reaction of metronidazole at the modified electrode was an irreversible process controlled by diffusion. Under optimum experimental conditions, the logarithm of catalytic currents shows a good linear relationship with that of the metronidazole concentration in the range of 0.1–600 µmol/L with a low detection limit of 14 nmol/L. In addition, the modified electrode exhibited satisfactory stability, sensitivity and reproducibility, and could be applied to the determination of metronidazole in an injection solution.
TL;DR: In this paper, the advances of nanostructured materials for DET of redox proteins in recent years, and is divided into applications in biosensors and biofuel cells, are discussed.
Abstract: Direct electrochemistry of redox proteins provides exciting platforms for performance improvement of biosensors and power enhancement of biofuel cells. Nanomaterials with tailored structures and unique properties are promising building blocks to promote direct electron transfer (DET) between redox-active cofactors of proteins and electrodes. This paper reviews the advances of nanostructured materials for DET of redox proteins in recent years, and is divided into applications in biosensors and biofuel cells. Both of them focus on the performance improvement, together with discussion on major challenges and opportunities for future research. The enhancement mechanism for direct electrochemistry is also reviewed for fundamental insights.
TL;DR: In this paper, molecularly imprinted polymeric films were prepared on the surface of a gold electrode by reductive electrochemical co-polymerization of 3-acrylamidophenylboronic acid (AABA), acrylamide (as spacer monomer), and N,N′-methylenebisacryamide(as crosslinker monomer).
Abstract: Molecularly imprinted polymeric films were prepared on the surface of a gold electrode by reductive electrochemical co-polymerization of 3-acrylamidophenylboronic acid (AABA), acrylamide (as spacer monomer), and N,N′-methylenebisacrylamide (as crosslinker monomer) in the presence of dopamine in water. The analytical determination of dopamine was investigated with this molecularly imprinted poly(AABA) film-modified gold electrode using cyclic voltammetry, electrochemical quartz crystal balance, and differential pulse voltammetry. The covalent nature of dopamine-boronic acid interaction as well as the negative charge on the molecularly imprinted polymeric film at physiological pH allowed excellent selectivity against ascorbic acid and other structurally similar interferents. The sensitivity of molecularly imprinted poly(AABA)-modified electrode was further improved by depositing a thin layer of multiwalled carbon nanotubes on the gold electrode surface prior to electropolymerization. The increased surface area due to the presence of carbon nanotubes improved the dopamine sensor’s detection limit to ∼20 nM as determined by differential pulse voltammetry. A linear dependence of peak current in the differential pulse voltammograms was obtained over the dopamine concentration range from 50 nM to 2 µM.
TL;DR: In this paper, ultrathin graphene (GN) nanosheets were uniformly decorated with nickel (Ni) nanoparticles, as confirmed by scanning electron microscopy and transmission electron microscope.
Abstract: In this paper, ultrathin graphene (GN) nanosheets were uniformly decorated with nickel (Ni) nanoparticles, as confirmed by scanning electron microscopy and transmission electron microscopy. This GNNi hybrid exhibited excellent accumulation and catalytic capacity for the simultaneous detection of sunset yellow and tartrazine, two colorants commonly found mixed in foodstuffs. The electrochemical reaction mechanism of sunset yellow and tartrazine were studied in detail on the GNNi nanocomposite modified glassy carbon electrode. In square wave voltammetry measurements, the oxidation peak potentials of sunset yellow and tartrazine were separated by about 250 mV. This novel proposed voltammetric method has good selectivity which was successfully applied for the simultaneous determination of sunset yellow and tartrazine in some food sample extracts.
TL;DR: In this article, the electrochemical oxidation of ibuprofen at a boron-doped diamond electrode (BDDE) and its voltammetric determination is reported for the first time.
Abstract: The electrochemical oxidation of ibuprofen at a boron-doped diamond electrode (BDDE) and its voltammetric determination is reported for the first time. A well-defined oxidation peak was observed at around 1.6 V in 0.1 mol L−1 H2SO4 solution with 10 % (v/v) ethanol at the BDDE surface activated by either cathodic or anodic pretreatments. A differential-pulse voltammetric method for the determination of ibuprofen in pharmaceutical formulations was optimized with a detection limit of 5 µmol L−1 and compared with the British Pharmacopeia method.