Indium Tin Oxide Electrode Surface Research Articles

Multiplexed electrochemical nucleic acid sensor based on visible light-mediated metal-free thiol-yne click reaction for simultaneous detection of different nucleic acid targets

Simultaneous detection of multiple tumor biomarkers with a simple and low-cost assay is crucial for early cancer detection and diagnosis. Herein, we presented a low-cost and simple assay for multiplexed detection of tumor biomarkers using a spatially separated electrodes strategy. The sensor is fabricated based on a metal-free thiol-yne click reaction, which is mediated by visible light, on commercially available indium tin oxide (ITO) electrodes. Four biomarkers, including p53 DNA, Brca2 DNA, K-ras DNA, and MicroRNA-204 RNA, were used as model analytes, and the corresponding oligonucleotide probes were modified on the desired electrode units sequentially with 530 nm irradiation light in the presence of photosensitizer Eosin Y. By this visible light-mediated coupling reaction, oligonucleotide probe densities of up to 9.2 ± 0.7 × 1010 molecules/cm2 were readily obtained on the ITO electrode surface. The proposed multiplexed E-NA sensor could detect four different nucleic acid targets concurrently without crosstalk among adjacent electrodes and was also successfully applied for detecting targets in a 20% fetal calf serum sample. The detection limits for p53 DNA, Brca2 DNA, K-ras DNA, and MicroRNA-204 RNA were 0.72 nM, 0.97 nM, 2.15 nM, and 1.73 nM, respectively. The developed approach not only has a great potential for developing cost-effective biosensors on affordable substrates for nucleic acid target detection, but also be easily extended to detect other targets by modifying the specific oligonucleotide probes anchored on the electrode.

Iodine-doped reduced graphene oxide and titanium dioxide nanocomposite as effective amperometric glucose biosensor

The current study fabricated a non-enzymatic glucose sensor based on iodine-doped reduced graphene oxide with titanium dioxide (I-rGO@TiO2) nanocomposite. Initially, the sol-gel and thermal reduction methods synthesized titanium dioxide (TiO2) nanoparticles and reduced graphene oxide (rGO). Then, the hydrothermal technique was utilized to synthesize a composite of I-rGO@TiO2 by combining I-rGO and TiO2 in a 1:4 ratio. The XRD spectrum and TEM images revealed that in the I-rGO@TiO2 nanocomposite, nanocrystalline anatase titanium is randomly distributed on the I-rGO sheets. Fourier transforms the infrared spectrum of nanocomposite shows the presence of titanium and oxygen bond characteristics peak between 400 and 850 cm−1. Iodine molecules peak at 100 cm−1 were obtained in Raman spectra. The AC conductivity and dielectric properties of the nanocomposite were analyzed. For the sensor fabrication, the indium tin oxide electrode surface is modified by I-rGO@TiO2, and the electrochemical performance was examined. At room temperature, the sensor demonstrated a wider linear detection range (0.5−10 mM). The lower detection limit of the sensor was 0.23 μM (S/N = 3), and the sensitivity was 221.69 μA mM−1 cm−2. The I-rGO@TiO2 nanocomposite shows a positive temperature coefficient via the thermal activation of charge carriers and a conductivity of 3.82 × 10−5 Ω−1m−1 at 200 °C. Additionally, the antibacterial properties was evaluated, and dose-dependent properties were observed towards E. coli and Bacillus subtilis bacterium.

Ti3C2TxMXene modified indium tin oxide (ITO) electrode for electrochemical sensing of bilirubin based on a molecularly imprinted pyrrole polymer

In this study for the first time we are developing Ti3C2TxMXene-based molecularly imprinted electrochemical sensor for the detection of bilirubin (BR). Firstly, Ti3C2TxMXene is synthesized by chemical etching and deposited at the ITO electrode surface by drop casting. After that, pyrrole as a monomer is electropolymerized in the presence of a sodium acetate buffer solution containing the BR template to prepare a BR-imprinted electrode. The modification of ITO electrode with Ti3C2TxMXene has not only imparted binding properties to the substrate that are very important for MIP formation but has also rendered excellent electrochemical characteristics to the electrode as monitored by CV, DPV, and EIS techniques. The sensing studies have been performed with synthetic samples that reveal the potential of prepared molecular imprinted electrochemical sensors toward BR detection. The linearity range, limit of detection, and limit of quantification are calculated as 10 μM to 90 μM, 0.197 μM and 0.598 μM, respectively. Selectivity, stability, and reproducibility are also reported for the prepared MIP sensor.

Innovative polymer engineering for the investigation of electrochemical properties and biosensing ability.

Subtle engineering for the generation of a biosensor from a conjugated polymer with the inclusion of fluorine-substituted benzothiadiazole and indole moieties is reported. The engineering includes the electrochemical copolymerization of the indole-6-carboxylic acid (M1) and 5-fluoro-4,7-bis(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (M2) on the indium tin oxide and graphite electrode surfaces for the investigation of both their electrochemical properties and biosensing abilities with their copolymer counterparts. The intermediates and final conjugated polymers, Poly(M1) [P-In6C], Poly(M2) [P-FBTz], and copoly(M1 and M2) [P-In6CFBTz], were entirely characterized by 1H NMR, 13C NMR, CV, UV-Vis-NIR spectrophotometry, and SEM techniques. HOMO energy levels of electrochemically obtained polymers were calculated from the oxidation onsets in anodic scans as -4.78 eV, -5.23 eV, and -4.89 eV, and optical bandgap (Egop) values were calculated from the onset of the lowest-energy π-π* transitions as 2.26 eV, 1.43 eV, and 1.59 eV for P-In6C, P-FBTz, and P-In6CFBTz, respectively. By incorporation of fluorine-substituted benzothiadiazole (M2) into the polymer backbone by electrochemical copolymerization, the poor electrochemical properties of P-In6C were remarkably improved. The polymer P-In6CFBTz demonstrated striking electrochemical properties such as a lower optical band gap, red-shifted absorption, multielectrochromic behavior, a lower switching time, and higher optical contrast. Overall, the newly developed copolymer, which combined the features of each monomer, showed superior electrochemical properties and was tested as a glucose-sensing framework, offering a low detection limit (0.011 mM) and a wide linear range (0.05-0.75 mM) with high sensitivity (44.056 μA mM-1 cm-2).

Homogeneous Electrochemical Aptasensor for Sensitive Detection of Zearalenone Using Nanocomposite Probe and Silica Nanochannel Film.

Developing rapid and efficient analytical methods is of great importance for food safety Herein, we present a novel homogeneous electrochemical aptasensor for ultrasensitive quantitative determination of zearalenone (ZEN) based on a nanocomposite probe and silica nanochannel film. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and UV-Vis characterization techniques confirm that graphene oxide (GO) bears an aromatic conjugated structure, along with hydroxyl and carboxyl groups, facilitating the subsequent adsorption of cationic redox hexa-ammine-ruthenium (III) (Ru(NH3)63+) and anionic ZEN aptamer, to form a Ru(NH3)63+-ZEN aptamer-GO nanocomposite probe in a homogeneous solution. Vertically-ordered mesoporous silica films (VMSF) bearing silanol groups can be simply grown on the solid indium tin oxide (ITO) electrode surface and enable the selective preconcentration of Ru(NH3)63+, eventually leading to signal amplification. Since the detachment of Ru(NH3)63+ from the GO surface by the recognized ZEN aptamer in the presence of ZEN, more free Ru(NH3)63+ is released in solution and produces enhanced redox signals at the VMSF modified ITO electrode, allowing quantitative detection of ZEN. On the basis of the above sensing strategy, the proposed homogeneity, due to the assistance of graphene, as well as of the signal amplification and anti-fouling effects of VMSF, accurate analysis of ZEN can be realized in maize and Chinese chestnut samples.

Highly sensitive electrochemical immunosensor based on electrodeposited platinum nanostructures confined in silica nanochannels for the detection of the carcinoembryonic antigen.

In this study, we report a highly sensitive electrochemical immunosensor for carcinoembryonic antigen (CEA) detection based on the electrodeposited platinum nanoparticles (Pt NPs) confined in the ultrasmall nanochannels of vertically ordered mesoporous silica film (VMSF). VMSF bearing amine groups (NH2-VMSF) can be prepared on the indium tin oxide electrode surface via a one-step co-condensation route using an electrochemically assisted self-assembly method, which renders a strong electrostatic effect for [PtCl6]2- and leads to the spatial confinement of Pt NPs inside the silica nanochannels after electrodeposition. The external surface of NH2-VMSF is functionalized with CEA antibodies using glutaraldehyde as a coupling agent, resulting in an electrochemical immunosensing interface with good specificity for CEA detection. Under optimal experimental conditions, high affinity between the CEA antibody and CEA produces a steric hindrance effect for the accessibility of the electrochemical probe ([Fe(CN)6]3-) in the bulk solution to the underlying indium tin oxide surface, eventually resulting in the attenuated electrochemical signal and enabling the detection of the CEA with a wide linear range of 0.01pg/mL∼10ng/mL and a pretty low limit of detection of 0.30fg/mL. Owing to the signal amplification ability of Pt NPs and the anti-biofouling property of NH2-VMSF, the as-prepared electrochemical immunosensor based on the Pt NPs@NH2-VMSF displays an accurate analysis of the CEA in human serum samples, holding significant promise for health monitoring and clinical diagnosis.

Hole Injection Characteristics and Annealing Temperature Dependence for Organic Light‐Emitting Diodes Using Spontaneous Polarization

An efficient carrier injection at the electrode/organic semiconductor interface of organic light‐emitting diodes (OLEDs) is challenging. It is well‐known that an electric dipole at the electrode/semiconductor interface improves the carrier injection from the electrode because of a vacuum‐level shift. In this study, poly (vinylidene fluoride‐trifluoroethylene) [P(VDF/TrFE)] is used as a polar polymer with spontaneous polarization. P(VDF/TrFE) is spin‐coated on an indium tin oxide (ITO) electrode surface as a hole injection layer for OLEDs. The P(VDF/TrFE) layer enhances the hole injection from the ITO electrode by causing a vacuum‐level shift. As a result, the device driving voltage can be lowered. In addition, annealing temperature dependence is observed. To investigate the origin of the hole injection effect, the P(VDF/TrFE)‐layered ITO surface and the thin film structure of the P(VDF/TrFE) layer are measured. The P(VDF/TrFE) layers at different annealing temperatures show no difference in surface properties but show significant differences in the thin film structure. The hole injection of OLEDs is significantly enhanced because of the structural change in ultrathin P(VDF/TrFE) layer.

CVD Graphene Electrode for Direct Electrochemical Detection of Double-Stranded DNA

Understanding and regulating DNA interactions with solvents and redox-active centers opens up new possibilities for improving electrochemical signals and developing adequate biosensors. This work reports the development of a modified indium tin oxide (ITO) electrode by chemical vapor deposition (CVD) of graphene for the detection of double-stranded DNA. The modified electrode shows a better electrical conductivity than ITO, as confirmed by electrochemical impedance spectroscopy (EIS), where a drastic decrease in the charge–transfer resistance, Rct, from ~320 to ~60 Ω was observed. Sequences of double-stranded genomic DNA with a different number of base pairs are evaluated through differential pulse voltammetry (DPV), using ferri/ferrocyanide ([Fe(CN)6]3−/4−) as a mediator in the solution. Variations in the electrochemical response of the [Fe(CN)6]3−/4− probe are observed after introducing redox inactive double-stranded DNA ions. The redox-active [Fe(CN)6]3−/4− probe serves as a scaffold to bring DNA into the graphene-modified ITO electrode surface, provoking an increase in the current and a change in the potential when the number of base pairs increases. These results are confirmed by EIS, which shows a variation in the Rct. The calibration of DPV intensity and Rct vs. DNA base pairs (bps) number were linear in the 495–607 bps range. The proposed method could replace the nucleic acid gel electrophoresis technique to determine the presence of a DNA fragment and quantify its size.

Signal-on low background electrochemiluminescence biosensor based on the target-triggered dual signal amplifications and difference of electrostatic attraction

The electrostatic attraction difference between negatively charged report probes and positively charged electrode had been applied to develop a signal-on low background electrochemiluminescence (ECL) biosensor for microRNA-141 (miRNA141, chosen as a model target) detection. Indium tin oxide (ITO) electrode was modified with poly-(allylamine hydrochloride) (PAH) to generate a positively charged surface. The electrostatic repulsion between dichlorotris (1,10-phenanthroline) ruthenium (Ⅱ) hydrate (Ru(phen)32+) and ITO electrode results in the low background signal. The target can trigger an enzyme-free isothermal catalytic hairpin self-assembly (CHA) and hybrid chain reaction (HCR) cascade reaction to generate a large amount of negatively charged long dsDNAs, which can be used to load Ru(phen)32+ (Ru-dsDNA) with high efficiency. Ru-dsDNA complexes are negatively charged and can easily accumulate on ITO electrode surface because of electrostatic attraction, which results in a strong ECL signal detected. The ECL intensity of the system was linearly correlated with the logarithm of microRNA-141 concentration in the range of 1 fM ∼ 5 pM with a detection limit of 0.17 fM (S/N = 3). The reliability of the proposed biosensor had been verified through the detection of targets in cell lysates.

Pronounced thickness effect of permanent charge-introduced branched poly(ethylene imine) surface-modifying layers in polymer:nonfullerene solar cells

Modification of electrode surfaces in polymer:nonfullerene solar cells have attracted keen interest because it greatly affects the device performance. In this study, we tried to modify the indium-tin oxide (ITO) electrode surface by introducing a branched poly(ethylene imine) (bPEI) nanolayer, which is doped with 3-hydroxypropane-1-sulfonic acid (HPSA), and investigated the thickness effect of HPSA-doped branched PEI layers on the performance of inverted-type polymer:nonfullerene solar cells. The doping ratio of HPSA to bPEI was set to 20 mol% to secure sufficient room for dipole formation, while the bPEI:HPSA thickness was varied between 0 and 5.5 nm. Results showed that the open circuit voltage of devices was remarkably increased by coating the 1.0–3.1 nm-thick bPEI:HPSA layers on the ITO electrodes. The efficiency of solar cells was strongly dependent on the bPEI:HPSA thickness and exhibited the highest efficiency (12.13 %) at 1.5 nm, which is much higher than ca. 7.7 % in the case of 1.5 nm-thick pristine bPEI layers. The improved performance of solar cells was correlated with surface morphology and wetting characteristics, electrode work function change and coverage effect by X-ray photoelectron spectroscopy, and device stability after 60-day storage.

Probe-Integrated Label-Free Electrochemical Immunosensor Based on Binary Nanocarbon Composites for Detection of CA19-9.

Convenient and sensitive detection of tumor biomarkers is crucial for the early diagnosis and treatment of cancer. Herein, we present a probe-integrated and label-free electrochemical immunosensor based on binary nanocarbon composites and surface-immobilized methylene blue (MB) redox probes for detection of carbohydrate antigen 199 (CA19-9), which is closely associated with gastric malignancies. Nanocarbon composites consisting of electrochemically reduced graphene oxides and carbon nanotubes (ErGO-CNT) are electrodeposited onto an indium tin oxide (ITO) electrode surface to form a 3D nanocomposite film, which could provide high surface area to immobilize abundant MB probes, facilitate the electron transfer of MB, and therefore, improve sensitivity. Polydopamine (PDA) served as a bifunctional linker is able to immobilize anti-CA19-9 antibodies and stabilize the inner probe, conferring the sensing interface with specific recognition capacity. Electrochemical detection of CA19-9 is achieved based on the decrease of the redox signal of MB after specific binding of CA19-9 with a wide linear range of 0.1 mU/mL to 100 U/mL and a limit of detection (LOD) of 0.54 nU/mL (S/N = 3). The constructed electrochemical immunosensor has good selectivity, repeatability, reproducibility, and stability. Furthermore, determination of CA19-9 in human serum samples is also realized.

Label-Free and Homogeneous Electrochemical Biosensor for Flap Endonuclease 1 Based on the Target-Triggered Difference in Electrostatic Interaction between Molecular Indicators and Electrode Surface.

Target-induced differences in the electrostatic interactions between methylene blue (MB) and indium tin oxide (ITO) electrode surface was firstly employed to develop a homogeneous electrochemical biosensor for flap endonuclease 1 (FEN1) detection. In the absence of FEN1, the positively charged methylene blue (MB) is free in the solution and can diffuse onto the negatively charged ITO electrode surface easily, resulting in an obvious electrochemical signal. Conversely, with the presence of FEN1, a 5′-flap is cleaved from the well-designed flapped dumbbell DNA probe (FDP). The remained DNA fragment forms a closed dumbbell DNA probe to trigger hyperbranched rolling circle amplification (HRCA) reaction, generating plentiful dsDNA sequences. A large amount of MB could be inserted into the produced dsDNA sequences to form MB-dsDNA complexes, which contain a large number of negative charges. Due to the strong electrostatic repulsion between MB-dsDNA complexes and the ITO electrode surface, a significant signal drop occurs. The signal change (ΔCurrent) shows a linear relationship with the logarithm of FEN1 concentration from 0.04 to 80.0 U/L with a low detection limit of 0.003 U/L (S/N = 3). This study provides a label-free and homogeneous electrochemical platform for evaluating FEN1 activity.

Vertically-Ordered Mesoporous Silica Films for Electrochemical Detection of Hg(II) Ion in Pharmaceuticals and Soil Samples.

Rapid and simple determination of mercury ion (Hg2+) in pharmaceuticals and soil samples is vital for human health and the environmental monitoring. Vertically-ordered mesoporous silica films (VMSF) supported by the indium tin oxide (ITO) electrode surface were prepared by electrochemically assisted self-assembly method and utilized for electrochemical detection of Hg2+. Owing to the negatively charged channel walls and ultrasmall pore diameter, VMSF displays obvious cationic selectivity and has highly electrostatic interaction for Hg2+, giving rise to the strong electrochemical signals. By recording the anodic stripping signals of adsorbed Hg2+ using differential pulse voltammetry, quantitative detection of Hg2+ was achieved with a wide linear range (0.2 μM–20 μM) and a low limit of detection (3 nM). Furthermore, considering the anti-fouling and anti-interference capacity of VMSF, the proposed VMSF/ITO sensor has been successfully applied to detect Hg2+ in pharmaceuticals and soil samples without tedious pretreatment processes of samples.

Electrochemiluminescence Biosensor for Hyaluronidase Based on the Adjustable Electrostatic Interaction between the Surface-Charge-Controllable Nanoparticles and Negatively Charged Electrode.

A novel electrochemiluminescence (ECL) biosensor for hyaluronidase (HAase) based on the adjustable electrostatic interaction between the surface-charge-controllable nanoparticles and negatively charged electrode has been devised. Hyaluronic acid (HA)-coated amino-modified ruthenium bipyridine-doped silica nanoparticles (Ru@SiO2-NH2@HA NPs) have been synthesized and act as ECL indicators, and the surface of this particle is negatively charged because HA contains a large amount of OH- and COO-. The strong electrostatic repulsion between the Ru@SiO2-NH2@HA NPs and negatively charged indium tin oxide (ITO) electrode surface leads to the detection of a low-intensity ECL signal. In the presence of HAase, the HA on the surface of the Ru@SiO2-NH2@HA NPs can be decomposed, and the particles can be transformed into positively charged amino-modified ruthenium bipyridine-doped silica nanoparticles (Ru@SiO2-NH2 NPs), which can be concentrated near the surface of the ITO electrode through electrostatic attraction, and result in the detection of an enhanced ECL signal. The ECL of the system has a good linear relationship with HAase concentration in the range of 2.0-60 U/mL, and the limit of detection was 0.37 U/mL. The designed biosensor had been applied to detect the target in real samples with satisfied results.

Bistable Silver Electrodeposition‐Based Electrochromic Device with Reversible Three‐State Optical Transformation By Using WO3 Nanoislands Modified ITO Electrode

AbstractA bistable electrochromic (EC) device which can reversibly transform between transparent, mirror, and black states based on reversible metal Ag electrodeposition is achieved by introducing 1) a (3‐mercaptopropyl) trimethoxysilane (MPTMS)‐treated indium‐tin‐oxide (ITO) glass electrode modified with WO3 nanoislands (WNs) as the rough surface and 2) ionic liquids (IL) into electrolyte to form an anion‐blocking layer, toward achieving long‐term memory performance. Typically, the EC cell is packaged by sandwiching gel electrolyte between the flat and WNs‐modified ITO electrodes. Under opposite voltages, this smart device can transfer from transparent to black (+2.5 V/9.4 s) or mirror (−2.5 V/8.3 s) state by depositing Ag on the WNs‐modified or flat ITO electrode surface, respectively. The assembled device exhibits over 80% mirror reflectance and below 10% transmittance of black state. After power off, both the black and mirror states remain bistability for a long time (>30 min) when IL are introduced into electrolyte for the EC device. The electrical double layer in the highly viscous electrolyte with IL contributes to form a barrier to bromide ions, which protects the Ag layer from dissolution at open circuit. This multifunctional energy‐efficient EC device has shown great potential and competitiveness for numerous applications compared to conventional EC devices.

Hierarchical self-constructed biomolecular nanolayers comprising cholesterol and cholesteryl hemisuccinate for automatic alignment of liquid crystals

Hierarchical supramolecular nanostructures are architecturally robust and functionally tunable, and therefore are widely utilized as functional building blocks for optoelectronic and biological applications. Herein, we report a simple and effective fabrication strategy to construct hierarchical biomolecular nanolayers comprising cholesterol and cholesteryl hemisuccinate for automatic alignment of liquid crystals (LCs) by using the programmed interfacial self-assembly of biomolecular amphiphiles on the polar electrode surface. The spontaneous formation of ultrathin biomolecular nanolayer was successfully achieved by simple doping and in situ self-organization of a small amount of steroid-based amphiphiles in the confined LC cell. The surface analysis demonstrated that the amphiphilic biomolecules of cholesterol and cholesteryl hemisuccinate formed hydrophobic self-constructed nanolayers with a dense surface coverage on the surface of indium tin oxide (ITO) electrode via hydrogen bonding. These nanolayers, bearing hydrophobic steroid groups and alkyl chains on their surface, induced uniform vertical alignment of LCs via van der Waals forces. Notably, the biomolecular nanolayer containing cholesteryl hemisuccinate exhibited more stably oriented LCs than cholesterol-based nanolayer at the same concentration owing to the strong interfacial hydrogen bonding with polar ITO electrode surface. The electro-optical properties of the LC cells containing the steroid-based amphiphiles revealed that hierarchical self-constructed nanolayers based on the amphiphilic biomolecules afforded low threshold voltage and fast response time comparable to those of conventional polyimide alignment layer.

Electrochemical Eu(III)/Eu(II) behaviors and recovery over terpyridyl-derivatized modified indium tin oxide electrode surfaces

Understanding the electrochemical behaviors of lanthanide (Ln) ions is essential for the treatment, separation, and recovery of radioactive materials and Ln-containing industry waste. Herein, the electrochemical behavior of Eu(III)/Eu(II) ions and their recovery were studied over terpyridine-functionalized indium tin oxide (ITO) electrodes. Two different functionalization processes were performed via Au-S bonding on Au nanoparticle-loaded ITO and amide bonding on an amino alkoxysilane-functionalized ITO. Cyclic voltammetry was performed for the electrodes, with and without surface functionalization, in electrolytes containing NaClO4 and H2SO4. Electrodeposition by amperometry was performed to recover Eu ions as EuSO4 on the developed electrodes at a reduction potential of ~1.0 V (vs. Ag/AgCl), which is an irreversible reduction potential in NaClO4 electrolyte. The electrodes were fully characterized by scanning electron microscopy, X-ray diffraction crystallography, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and fluorescence lifetime measurements. Density functional theory calculations at the B3LYP/GENECP level of theory were employed for geometry optimization and the electronic energy state calculation for the complexation of Eu(III) and Eu(II) ions with the functionalized groups. The results obtained herein provide valuable information on the development of electrodes for the treatment of Ln and other related elements.

Construction of a novel photoelectrochemical sensor for detecting trace amount of copper (II) ion

A photoelectrochemical (PEC) sensor for determination of copper (II) ion has been developed. The indium tin oxide (ITO) electrode modified by ZnS quantum dots (QDs) was used as working electrode and dopamine (DA) as detection solution. When different amounts of Cu2+ were added, the polydopamine-copper (II) complex (PDA-Cu (II)) was in suit formed and attached tightly to the surface of ITO electrode based on the interaction between copper (II) and dopamine (DA) under weakly alkaline (pH 8.00) solution. The detection of Cu2+ was achieved by means of the decreasing photocurrent. The linear range of 1 - 1000 pM and sensitivity of 0.45 pM were obtained. In addition, the formation of PDA-Cu (II) was characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Thus, a PEC sensor based on the change of electrode surface state can realize the sensitive detection of Cu2+.

A novel electrochemical immunosensor based on acetylene black/epoxy-substituted-polypyrrole polymer composite for the highly sensitive and selective detection of interleukin 6

An ultrasensitive immunosensor based on acetylene black (AB)/epoxy-substituted-poly(pyrrole) polymer (EpxS-PPyr) composite coated disposable indium tin oxide (ITO) electrode was fabricated for interleukin 6 (IL 6) detection. The EpxS-PPyr polymer was a promising matrix material to increase the loading capacity of immunosensor owing to its large surface area and abundance of epoxy groups. EpxS-PPyr polymer was synthesized by an esterification reaction and used to attach IL 6 receptor owing to its excellent biocompatibility and good conductivity. The electrochemical signals of the electrodes during the immunosensor fabrication were performed with electrochemical impedance spectroscopy and cyclic voltammetry techniques. Additionally, the changes formed on ITO electrode surfaces were followed by scanning electron microscopy and atomic force microscopy analyses. Under optimized conditions, the designed biosensor illustrated an ultra-sensitive signal towards IL 6 antigen at a broad concentration range from 0.01 pg/mL to 50 pg/mL. The detection limit and sensitivity were found as 3.2 fg/mL and 0.29 pg−1mLkΩ cm−2, respectively. Acceptable reproducibility, good storage-stability and excellent selectivity were found for IL 6 determination. Moreover, the proposed biosensor was applied to human serums and the recovery rates were ranged from 99.5 to 100.5 indicating acceptable accuracy. The results illustrated that this immunosensor were suitable for detection of IL 6 in clinical samples.

Different Electrochemical Sensor Designs Based on Diazonium Salts and Gold Nanoparticles for Pico Molar Detection of Metals.

We report a comparison of sensors’ performance of different hybrid nanomaterial architectures modifying an indium tin oxide (ITO) electrode surface. Diazonium salts and gold nanoparticles (AuNPs) were used as building units to design hybrid thin films of successive layers on the ITO electrode surface. Different architectures of hybrid thin films were prepared and characterized with different techniques, such as TEM, FEG-SEM, XPS, and EIS. The prepared electrodes were used to fabricate sensors for heavy metal detection and their performances were investigated using the square wave voltammetry (SWV) method. The comparison of the obtained results shows that the deposition of AuNPs on the ITO surface, and their subsequent functionalization by diazonium salt, is the best performing architecture achieving a high sensitivity in terms of the lower detection limit of pico molar.