Printed Carbon Electrode Research Articles

Construction of Metal-Organic Framework as a Novel Platform for Ratiometric Determination of Cyanide.

Metal-organic frameworks (MOFs) are frequently utilized as sensing materials. Unfortunately, the low conductivity of MOFs hinder their further application in electrochemical determination. To overcome this limitation, a novel modification strategy for MOFs was proposed, establishing an electrochemical determination method for cyanides in Baijiu. Co and Ni were synergistically used as the metal active centers, with meso-Tetra(4-carboxyphenyl)porphine (TCPP) and Ferrocenecarboxylic acid (Fc-COOH) serving as the main ligands, synthesizing Ni/Co-MOF-TCPP-Fc through a hydrothermal method. The prepared MOF exhibited improved conductivity and stable ratio signals, enabling rapid and sensitive determination of cyanides. The screen-printed carbon electrodes (SPCE) were suitable for in situ and real-time determination of cyanide by electrochemical sensors due to their portability, low cost, and ease of mass production. A logarithmic linear response in the range of 0.196~44 ng/mL was demonstrated by this method, and the limit of detection (LOD) was 0.052 ng/mL. Compared with other methods, the sensor was constructed by a one-step synthesis method, which greatly simplifies the analysis process, and the determination time required was only 4 min. During natural cyanide determinations, recommended readouts match well with GC-MS with less than 5.9% relative error. Moreover, this electrochemical sensor presented a promising method for assessing the safety of cyanides in Baijiu.

Surface Modification of Screen-Printed Carbon Electrode through Oxygen Plasma to Enhance Biosensor Sensitivity.

The screen-printed carbon electrode (SPCE) is a useful technology that has been widely used in the practical application of biosensors oriented to point-of-care testing (POCT) due to its characteristics of cost-effectiveness, disposability, miniaturization, wide potential window, and simple electrode design. Compared with gold or platinum electrodes, surface modification is difficult because the carbon surface is chemically or physically stable. Oxygen plasma (O2) can easily produce carboxyl groups on the carbon surface, which act as scaffolds for covalent bonds. However, the effect of O2-plasma treatment on electrode performance remains to be investigated from an electrochemical perspective, and sensor performance can be improved by clarifying the surface conditions of plasma-treated biosensors. In this research, we compared antibody modification by plasma treatment and physical adsorption, using our novel immunosensor based on gold nanoparticles (AuNPs). Consequently, the O2-plasma treatment produced carboxyl groups on the electrode surface that changed the electrochemical properties owing to electrostatic interactions. In this study, we compared the following four cases of SPCE modification: O2-plasma-treated electrode/covalent-bonded antibody (a); O2-plasma-treated electrode/physical adsorbed antibody (b); bare electrode/covalent-bonded antibody (c); and bare electrode/physical absorbed antibody (d). The limits of detection (LOD) were 0.50 ng/mL (a), 9.7 ng/mL (b), 0.54 ng/mL (c), and 1.2 ng/mL (d). The slopes of the linear response range were 0.039, 0.029, 0.014, and 0.022. The LOD of (a) was 2.4 times higher than the conventional condition (d), The slope of (a) showed higher sensitivity than other cases (b~d). This is because the plasma treatment generated many carboxyl groups and increased the number of antibody adsorption sites. In summary, the O2-plasma treatment was found to modify the electrode surface conditions and improve the amount of antibody modifications. In the future, O2-plasma treatment could be used as a simple method for modifying various molecular recognition elements on printed carbon electrodes.

The first demonstration of entirely roll-to-roll fabricated perovskite solar cell modules under ambient room conditions

The rapid development of organic-inorganic hybrid perovskite solar cells has resulted in laboratory-scale devices having power conversion efficiencies that are competitive with commercialised technologies. However, hybrid perovskite solar cells are yet to make an impact beyond the research community, with translation to large-area devices fabricated by industry-relevant manufacturing methods remaining a critical challenge. Here we report the first demonstration of hybrid perovskite solar cell modules, comprising serially-interconnected cells, produced entirely using industrial roll-to-roll printing tools under ambient room conditions. As part of this development, costly vacuum-deposited metal electrodes are replaced with printed carbon electrodes. A high-throughput experiment involving the analysis of batches of 1600 cells produced using 20 parameter combinations enabled rapid optimisation over a large parameter space. The optimised roll-to-roll fabricated hybrid perovskite solar cells show power conversion efficiencies of up to 15.5% for individual small-area cells and 11.0% for serially-interconnected cells in large-area modules. Based on the devices produced in this work, a cost of ~0.7 USD W−1 is predicted for a production rate of 1,000,000 m² per year in Australia, with potential for further significant cost reductions.

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.

Understanding the electrochemical interaction between the hybrid bilayer lipid membranes and amyloid‐β

AbstractBackgroundBiomimetic membrane systems can be deposited onto conductive metal surfaces to study the physical properties of membranes as well as the behaviour of proteins within these membranes using electrochemical and surface analytical techniques [1]. Although there are several types of biomimetic membrane, hybrid bilayer lipid membranes (HBLMs) have attracted wide interest. Traditionally, HBLMs have been developed by electrodepositing alkanethiol self‐assembled monolayers onto gold surfaces, which can then be further modified by depositing a secondary phospholipid layer to form the HBLM. Although HBLMs have been widely regarded due to them being robust, relatively straightforward to make, as well as being easy to modify according to the users needs, several concerns surround HBLMs including their reduced fluidity compared to true cell membranes. This is due to the alkanethiol layer being crystalline in nature and more densely packed, resulting in difficulty to reconstitute transmembrane proteins within them.MethodScreen‐printed carbon electrodes are modified with diazonium based phenyl alkyl groups using different protocols to evaluate the biomimetic differences of these novel HBLMs. 2,2‐diphenyl‐1‐picrylhydrazyl is used to prevent the formation of polyaryl layers on the surface of the electrode, hence limiting the electrodeposition to a monolayer. The HBLMs are formed by depositing the second layer in the form of dihexadecyl phosphate, which are analyzed using differential pulse voltammetry, ellipsometry, and X‐ray photoelectron spectroscopy.ResultThe different HBLMs presented are embedded with amyloid‐β1‐42 (Aβ42), the hallmark protein implicated in Alzheimer’s Disease, to assess the protein‐membrane interactions using HBLMs. Aβ42 is known to aggregate to form dimers, oligomers, fibrils, and plaques. Hence using electrochemical techniques, we are able to monitor the aggregation of Aβ42 in the HBLMs. The aggregation process was accelerated by the presence of the bilayer membrane.ConclusionThe electrochemical platform presented here enables us to understand how the interaction of amyloid‐β with the bilayer membrane can alter the aggregation pathways and also affect the formation of toxic oligomer species.

Application of electrochemical sensor modified by SBA-15 /Fe3O4/polyaniline nanocomposite for determination of tyrosine in milk samples

In this study, a selective SBA-15 /Fe3O4/Polyaniline /Chitosan nanocomposite was successfully electrodeposited on Screen- Printed Carbon Electrode (SPCE) and used for L-Tyrosine (Tyr) detection.Biological diagnostic probes such as artificial receptors are one of the important diagnostic layers for the identification of vital biomolecules, including essential amino acids like Tyr. A new electrochemical sensing platform based on differential pulse voltammetry was prepared for selective determination of Tyr in milk samples.SBA-15 nanoparticles were synthesized from corn leaves as a source of silica. These high-absorbance nanoparticles have been used for surface modification of SPCE. The morphology and electrochemical performance of the modified electrode were characterized by X-ray diffraction, scanning electron microscopy (SEM), transition electron microscopy (TEM), Furrier transform infrared spectroscopy (FTIR), Brunauer-Emmett–Teller techniques, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry(CV).As a novel modified electrode, the catalytic activity of the modified SPCE towards electro-oxidation of Tyr was measured by differential pulse voltammetry (DPV). The experimental conditions, including the adsorption time, scan rates, the ratio of SBA-15, pH value, and applied potential, are investigated in detail.Electrochemical sensor based on SBA-15 (SPCE/SBA-15/Fe3O4/Polyaniline /Chitosan) Compared with SPCE/Fe3O4/Polyaniline/Chitosan shows good sensitivity, repeatability, reproducibility, low detection limit and high selectivity.In addition, a linear correlation between oxidation peak current and concentration of Tyr in the ranges 0.1–250 μM with a detection limit of 0.05 μM (S/N = 3) was obtained. Eventually, the suggested sensor was used for quantification of Tyr in real samples, by adding standard solutions to the milk samples.

Controlled electrodeposition of brookite TiO2 for photoelectroanalysis at printed carbon electrodes

TiO2-based photoelectrochemical (PEC) (bio)sensors have high photoactivity, chemical stability, and biocompatibility. However, their performance depends on multiple factors, including deposition method, morphology, and interaction with the target analyte. Herein, we describe a PEC platform based on TiO2 electrodeposition directly onto printed carbon electrodes (without heat treatment), designed for point-of-care (POC) applications. Brookite TiO2 nanocrystals were synthesized via electrodeposition in an acidic solution containing TiCl3, and parameters such as pH and temperature were optimized to improve photoelectrocatalytic activity. Photoelectrooxidation of ascorbic acid (AA) with electrodes prepared under optimal conditions (pH 2.5, 80 °C) had 10.5 times higher photocurrents than electrodes modified with commercial TiO2 nanoparticles via drop casting. The resulting sensor was highly sensitive and selective for AA, with a linear range from 10 to 1000 µM and a limit of detection of 3.25 µM (S/N = 3). Since brookite TiO2 electrodeposition does not require thermal treatment, printed carbon electrodes on polymer substrates can be used in producing miniaturized devices for sensitive, selective PEC (bio)sensors.

Organic Bromide Salts Interface Modification for High‐Efficiency Perovskite Solar Cells with Printed Carbon Electrode

Perovskite solar cells (PSCs) using carbon as the counter electrode fabricated through a low‐temperature full solution‐process method can significantly simplify the preparation process and reduce production cost. Herein, a high‐performance PSC is presented with printed carbon electrode and dopant‐free poly(3‐hexylthiophene) (P3HT) is employed as hole transport materials. Different organic bromide salts are employed to modify the perovskite/P3HT interface to further enhance the performance. As a result, methylammonium bromide (MABr) modification significantly enhances the device open‐voltage (Voc) and fill factor (FF) by reducing interface defects and facilitates charge transport. A champion power conversion efficiency (PCE) of 19.22% (Voc of 1.118 V, FF of 0.765, and short‐circuit current of 22.48 mA cm−2) is achieved with MABr modification. The unencapsulated devices maintain 96% of the initial efficiency after storage for 3600 h and 88% after thermal treatment at 70 °C for 1200 h. Additionally, perovskite solar modules are also prepared based on printing and interface passivation route with PCE reaches 13.20%. These results represent an important progress in the enhancement of device PCE and up‐scaling of PSCs with cost‐effective, stable, and printed carbon electrode.

Sequential injection analysis for mercury ion with modified screen – printed carbon electrode

In this study, we developed a simple high-throughput and cost-effective method for monitoring toxic metal ion in an environmental aqueous sample. Mercury ion determination with Sequential Injection Analysis system (SIAs) coupled with the electrochemical detection on the modified screen-printed carbon working electrode (SPCE) is an alternative green analysis of mercury ion. The gold film was used as the modified material for improved mercury ion analysis in the automated system without memory effect on the electrode. Mercury oxidation signal was found at the potential of 0.7 V in 0.1 M HNO3 and 1.0 M HCl with the concentration low to 0.25 ± 0.18 mg×L-1. Online sample preparation and separation will study in the further experiment.

Electrophysiological investigation of intact retina with soft printed organic neural interface

Objective. Understanding how the retina converts a natural image or an electrically stimulated one into neural firing patterns is the focus of on-going research activities. Ex vivo, the retina can be readily investigated using multi electrode arrays (MEAs). However, MEA recording and stimulation from an intact retina (in the eye) has been so far insufficient. Approach. In the present study, we report new soft carbon electrode arrays suitable for recording and stimulating neural activity in an intact retina. Screen-printing of carbon ink on 20 µm polyurethane (PU) film was used to realize electrode arrays with electrodes as small as 40 µm in diameter. Passivation was achieved with a holey membrane, realized using laser drilling in a thin (50 µm) PU film. Plasma polymerized 3.4-ethylenedioxythiophene was used to coat the electrode array to improve the electrode specific capacitance. Chick retinas, embryonic stage day 13, both explanted and intact inside an enucleated eye, were used. Main results. A novel fabrication process based on printed carbon electrodes was developed and yielded high capacitance electrodes on a soft substrate. Ex vivo electrical recording of retina activity with carbon electrodes is demonstrated. With the addition of organic photo-capacitors, simultaneous photo-electrical stimulation and electrical recording was achieved. Finally, electrical activity recordings from an intact chick retina (inside enucleated eyes) were demonstrated. Both photosensitive retinal ganglion cell responses and spontaneous retina waves were recorded and their features analyzed. Significance. Results of this study demonstrated soft electrode arrays with unique properties, suitable for simultaneous recording and photo-electrical stimulation of the retina at high fidelity. This novel electrode technology opens up new frontiers in the study of neural tissue in vivo.

Flow injection amperometric sensing of hydroxylamine at a Cu(ii)–neocuproine-functionalized multiwalled carbon nanotube/screen printed carbon electrode

In the electrocatalytic oxidation mechanism of NH2OH at modified electrode, firstly NH2OH reacted with [Cu(Ncp)2]2+and oxidized to N2O. The formed [Cu(Ncp)2]+was reoxidized by giving electrons to electrode resulting in enhancement of anodic current.

Block Iodide, Save Perovskite Modules

Stability of small area perovskite solar cells has been notably improved, but large area modules have not been proven stable. Recently in Joule, E. Bi and coworkers present a highly stable perovskite module that kept 90% of its initial efficiency after 1,000 h operation under illumination. The secret is an iodide diffusion blocking layer (DBL) added at the module interconnection. The DBL with 2D graphitic carbon nitride (g-C3N4) flakes can suppress iodide diffusion at the interconnection and prevent electrode corrosion.

A disposable electrochemical sensor based on electrospinning of molecularly imprinted nanohybrid films for highly sensitive determination of the organotin acaricide cyhexatin.

Nanofibrous polyporous membranes imprinted with cyhexatin (CYT) were formed via the ordered distribution of the imprints in electrospun nanofibers. The MIPs have a high mass transfer rate and enhanced adsorption capacity. In addition, a printed carbon electrode with enhanced sensitivity was developed via electrochemical fabrication of reduced graphene oxide (rGO) and gold nanoparticles (AuNPs). The molecularly imprinted sensor exhibits excellent selectivity and sensitivity for CYT. The structure and morphology of the nanohybrid films were characterized by using scanning electron microscopy, atomic force microscopy and chronoamperometry. The sensing performances were evaluated by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy by using hexacyanoferrate(IV) as an electrochemical probe. The electrode, best operated at a working potential of around 0.16V (vs. Ag/AgCl), has a linear response in the1-800ngmL-1 CYT concentration range and a detection limit of 0.17ngmL-1 (at S/N = 3). The sensor demonstrated satisfactory recoveries when applied to the determination of CYT in spiked pear samples. Graphical abstract Schematic presentation of the electrochemical sensor for detection of CYT.

Dextran modified magnetic nanoparticles based solid phase extraction coupled with linear sweep voltammetry for the speciation of Cr(VI) and Cr(III) in tea, coffee, and mineral water samples

A simple and fast solid phase microextraction method using magnetic dextran (Sephadex G-150) as a sorbent was developed for the extraction, separation and speciation analysis of chromium ions. The retained Cr(VI) ions on the magnetic dextran sorbents were eluted and detected by linear sweep voltammetry at the gold nanoparticles modified screen- printed carbon electrode. The linear range, detection limit, quantification limit, and preconcentration factor of the established method for Cr(VI) and Cr(III) were calculated to be 0.5–10 μM, 0.01 μM, 0.1 μM, and 40, respectively. Chromium(III) concentration was determined after conversion of Cr(III) to Cr(VI) by H2O2 in alkaline media (NH4OH). The method was successfully applied to the speciation and determination of Cr(VI) and Cr(III) in artificial water and food samples using the standard addition method. The applicability of the method was confirmed by analysis of real food samples yielding good recovery values (92% and 102%).

Fabrication of a novel and ultrasensitive label-free electrochemical aptasensor for detection of biomarker prostate specific antigen

In this study, a novel and efficient aptasensor based on immobilization of thiol terminated prostate specific antigen (PSA) binding DNA aptamer onto Au nanoparticles/fullerene C60-chitosan-ionic liquid/multiwalled carbon nanotubes/screen printed carbon electrode has been fabricated for ultrasensitive aptasensing of biomarker PSA. Formation of PSA-aptamer complex caused a variation in electrochemical impedance spectroscopic (EIS) and differential pulse voltammetric (DPV) responses of the aptasensor which enabled us to aptasensing of the PSA by EIS and DPV methods. Morphology and electrochemical properties of the fabricated aptasensor were examined by scanning electron microscopy (SEM), cyclic voltammetry (CV) and EIS. The aptasensor was successfully applied to the determination of PSA by EIS and DPV in the range of 1–200 pg mL−1 with a limit of detection (LOD) of 0.5 pg mL−1 and 2.5–90 ng mL−1 with a LOD of 1.5 ng mL−1, respectively. This aptasensor exhibited outstanding anti-interference ability towards co-existing molecules with good stability, sensitivity, repeatability and reproducibility. Practical application of the aptasensor was examined with analysis of the PSA levels in serum samples obtained from patients with prostate cancer using both the aptasensor and a reference method. The results revealed the proposed system to be a promising candidate for clinical analysis of PSA.

Development of a nickel oxide/oxyhydroxide-modified printed carbon electrode as an all solid-state sensor for potentiometric phosphate detection

This work describes the preparation, characterization and use of a nickel oxide/oxyhydroxide-printed carbon electrode as an efficient potentiometric phosphate sensor.

Highly active nanostructured water oxidation catalyst electrodeposited from Co(cyclam) complex

The water soluble molecular complex [Co(cyclam)(ClO4)]ClO4 (cyclam = 1,4,8,11-tetraazacyclotetradecane) is utilized as a precursor for deposition of highly active cobalt based nanostructured material on the electrode surface upon electrooxidation. The electrolysis of the complex at +1.1 V vs Ag/AgCl in 0.1 M potassium phosphate at pH 12 leads to the formation of a nanoporous Co(II) hydroxide/phosphate thin film on the printed carbon electrode. The deposited surface was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). The modified electrode (Co-PCE-12) is stable for more than 34 h during the continuous electrolysis. The modified electrode exhibits a high water oxidation catalytic activity of 6.5 mA cm−2 at an overpotential of 580 mV (0.9 V vs Ag/AgCl (3 M KCl) at pH 12) with 98% Faradaic yield.

Electrochemical Behaviour of Nanoscale Ni Modified Screen- Printed Carbon Electrodes in Corrosion Tests and Hydrogen Evolution Electrocatalysis

Electrochemical Behaviour of Nanoscale Ni Modified Screen- Printed Carbon Electrodes in Corrosion Tests and Hydrogen Evolution Electrocatalysis

Protein detecting with smartphone-controlled electrochemical impedance spectroscopy for point-of-care applications

Proteins play crucial roles in biological activities and show close relationship with human diseases as biomarkers. Thus, rapid, sensitive, selective, and portable detection of protein is in high demand for point-of-care (POC) testing. Here, a smartphone-controlled biosensor system is developed with electrochemical impedance spectroscopy (EIS) to detect proteins for POC testing. The system was constituted by miniaturized biosensor, hand-held EIS detector, and smartphone, collectively. Printed carbon electrodes and interdigital gold electrodes, were modified with bio-components and integrated into the system as biosensors for protein detection. Then, detections of bull serum albumin (BSA) and thrombin demonstrated analytical performances of the system for quantification of the protein binding and enzyme activities by special antibodies and peptides immobilized on the electrodes. By the impedance measurement, the system could detect BSA and thrombin as low as 1.78μg/ml and 2.97ng/ml, respectively. The results suggested that the smartphone-controlled biosensor system provided a portable and cost-effective platform that allowed integration of diverse biosensor formats for different kinds of protein quantifications for POC testing.

Biossensor amperométrico para determinação de peróxido de hidrogênio em leite

Um biossensor amperométrico foi desenvolvido para detecção de peróxido de hidrogênio em amostras de leite. O biossensor foi construído a partir da imobilização de enzima peroxidase sobre eletrodo impresso de carbono. Parâmetros de otimização visando um melhor desempenho do biossensor foram avaliados. O biossensor apresentou linearidade no intervalo de 5,0 a 40,0 µ mol L-1 de H2O2 em tampão fosfato. Em amostras de leite sem diluição, os limites de detecção e quantificação foram de 0,42 µmol L-1 e 1,39 µmol L-1, respectivamente. O biossensor mostrou-se uma alternativa sensível e de baixo custo na detecção de H2O2 em amostras adulteradas de leite.