Quantitative Determination of Triiodothyronine by Electrochemical Impedance Spectroscopic Biosensor Using Gold Nanoparticle-Modified Electrode

A label-free electrochemical impedimetric immunosensor for the detection of Triiodothyronine—a thyroid hormone that functions as the biomarker for monitoring for thyroid dysfunction was developed. The gold nanoparticle-modified electrode was employed to achieve the sensitive determination of Triiodothyronine at a low concentration level. The gold nanoparticle layer on the gold electrode was generated by chronoamperometry method and its resulting characteristics were investigated by scanning electron microscopy. Redox probe [Fe(CN)6]3−/4− and electrochemical impedance spec-troscopy was used for both evaluation of the immobilization of anti-Triiodothyronine antibody on the electrode surface and quantitative determination of target Triiodothyronine in different concentrations. The electrode with absorbed antibodies showed significant changes in charge transfer resistance upon binding the antigen, which resulted in an increase in normalized impedance change as the addition of antigen concentrations over a dynamic linear range of 0.01–100 ng/ml. These results indicated that the proposed immunosensor could be a potential alternative method for determination of Triiodothyronine in clinics with the advantage of low cost and less time-consuming.

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Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

10.26434/chemrxiv.7991129 ◽

2019 ◽

Author(s):

Charlys Bezerra ◽

Géssica Santos ◽

Marilia Pupo ◽

Maria Gomes ◽

Ronaldo Silva ◽

...

Keyword(s):

Thermal Decomposition ◽

Polyvinyl Alcohol ◽

High Efficiency ◽

Electrochemical Impedance ◽

Pechini Method ◽

Low Cost ◽

Charge Transfer Resistance ◽

Transfer Resistance ◽

Calcination Temperatures ◽

Service Lifetime

Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO2–IrO2 anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO2 and IrO2 have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO2–IrO2 anodes with improved properties that can be further extended to synthesise other MMO compositions.

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Breast cancer detection using charge sensors coupled to DNA monolayer

MRS Proceedings ◽

10.1557/opl.2015.671 ◽

2015 ◽

Vol 1793 ◽

pp. 19-26

Author(s):

Marina R. Batistuti ◽

Marcelo Mulato ◽

Paulo R. Bueno

Keyword(s):

Breast Cancer ◽

Dna Sequence ◽

Dna Sequences ◽

Electrochemical Impedance ◽

Redox System ◽

Charge Transfer Resistance ◽

Label Free ◽

Self Assembled Monolayer ◽

Transfer Resistance ◽

Complementary Dna

ABSTRACTWe report the development of a label-free biosensors based on DNA hybridization, using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). This study uses DNA sequences based on microRNA related with breast cancer. The biosensor was fabricated by immobilizing a self-assembled monolayer of single-stranded 23-mer oligonucleotide (ssDNA) via a thiol linker on gold work electrodes. Residual binding places were filled with 6 -mercaptohexanol (MCH). The electrode was electrochemicaly characterized in the presence of a redox system ferri/ferrocyanide. Different concentrations of complementary DNA sequence for hybridization were incubated; an increase of charge transfer resistance (Rct) was observed, used as sensor parameter and correlated with concentrations of complementary DNA sequence. A debate was presented on the effect of the MgCl2 influence on ssDNA immobilization solution.

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Electrochemical properties and thermal stability of epoxy coatings electrodeposited on aluminium and modified aluminium surfaces

Journal of the Serbian Chemical Society ◽

10.2298/jsc0112871m ◽

2001 ◽

Vol 66 (11-12) ◽

pp. 871-880 ◽

Cited By ~ 1

Author(s):

Vesna Miskovic-Stankovic ◽

Zorica Lazarevic ◽

Zorica Kacarevic-Popovic

Keyword(s):

Thermal Stability ◽

Electrochemical Impedance ◽

Corrosion Behaviour ◽

Charge Transfer Resistance ◽

Epoxy Coatings ◽

Transfer Resistance ◽

Protective Properties ◽

Chemically Modified ◽

Thermal Stability Of

The corrosion behaviour of epoxy coatings electrodeposited on aluminium, as well as on electrochemically and chemically modified aluminium were investigated during exposure to 3 % NaCl. Electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA) were used for the determination of the protective properties of epoxy coatings on aluminium, anodized aluminium, phosphatized and chromatized-phosphatized aluminium. The protective properties of epoxy coatings on anodized and chromatized-phosphatized aluminium are significantly improved with respect to the same epoxy coatings on aluminium and phosphatized aluminium: higher values of the pore resitance and charge-transfer resistance, lower values of the coating capacitance, double-layer capacitance and relative permittivity (from EIS) smaller amount of absorbed water inside the coating (From TGA). On the other hand, the lower values of the ipdt temperature indicate a lower thermal stability of the epoxy coatings on anodized and chromatized-phosphatized aluminium.

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Rapid Determination of Ochratoxin A in Grape and Its Commodities Based on a Label-Free Impedimetric Aptasensor Constructed by Layer-by-Layer Self-Assembly

Toxins ◽

10.3390/toxins11020071 ◽

2019 ◽

Vol 11 (2) ◽

pp. 71 ◽

Cited By ~ 8

Author(s):

Mina Nan ◽

Yang Bi ◽

Huali Xue ◽

Sulin Xue ◽

Haitao Long ◽

...

Keyword(s):

Ochratoxin A ◽

Self Assembly ◽

Electrochemical Impedance ◽

Rapid Determination ◽

Grape Juice ◽

High Sensitivity ◽

Layer By Layer ◽

Label Free ◽

Transfer Resistance

A simple and sensitive label-free impedimetric aptasensor for rapid determination of ochratoxin A (OTA) has been developed, which was based on the combination between thiolated aptamer and gold nanoparticles by layer-by-layer self-assembly. Because of the interaction between aptamer and OTA, the relative normalized electron-transfer resistance (ΔRct) values obtained by electrochemical impedance spectroscopy (EIS) was proportional to the concentration of OTA and showed a good linear relationship from 0.1 to 10.0 ng/mL, with a lower detection limit (0.030 ng/mL) than one-step thiolated DNA aptasensor. The established method was successfully applied to detect and analyze OTA in table wine and grape juice, and the recovery was 90.56%–104.21% when PVP effective removed of phenolic substances. The label-free impedimetric aptasensor was used for rapid detection and quantitation of OTA in the inoculated grapes with the Aspergillus Nigri (H1), and the production of OTA (62.4 μg/kg, 20 μg/kg) far exceeded the maximum levels of 2 μg/kg after inoculation for three days. The developed method exhibited a good specificity, high sensitivity, time-efficient, and it could be applied to detect the OTA concentration in grape and its commodities.

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Electrochemical Resistive DNA Biosensor for the Detection of HPV Type 16

Molecules ◽

10.3390/molecules26113436 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3436

Author(s):

José R. Espinosa ◽

Marisol Galván ◽

Arturo S. Quiñones ◽

Jorge L. Ayala ◽

Verónica Ávila ◽

...

Keyword(s):

Modified Electrode ◽

Point Of Care ◽

Low Cost ◽

Relaxation Method ◽

Charge Transfer Resistance ◽

Dna Biosensor ◽

Complementary Sequence ◽

Transfer Resistance ◽

20 Nm ◽

Current Relaxation

In this work, a low-cost and rapid electrochemical resistive DNA biosensor based on the current relaxation method is described. A DNA probe, complementary to the specific human papillomavirus type 16 (HPV-16) sequence, was immobilized onto a screen-printed gold electrode. DNA hybridization was detected by applying a potential step of 30 mV to the system, composed of an external capacitor and the modified electrode DNA/gold, for 750 µs and then relaxed back to the OCP, at which point the voltage and current discharging curves are registered for 25 ms. From the discharging curves, the potential and current relaxation were evaluated, and by using Ohm’s law, the charge transfer resistance through the DNA-modified electrode was calculated. The presence of a complementary sequence was detected by the change in resistance when the ssDNA is transformed in dsDNA due to the hybridization event. The target DNA concentration was detected in the range of 5 to 20 nM. The results showed a good fit to the regression equation ΔRtotal(Ω)=2.99 × [DNA]+81.55, and a detection limit of 2.39 nM was obtained. As the sensing approach uses a direct current, the electronic architecture of the biosensor is simple and allows for the separation of faradic and nonfaradaic contributions. The simple electrochemical resistive biosensor reported here is a good candidate for the point-of-care diagnosis of HPV at a low cost and in a short detection time.

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Developing Activated Carbon Veil Electrode for Sensing Salivary Uric Acid

Biosensors ◽

10.3390/bios11080287 ◽

2021 ◽

Vol 11 (8) ◽

pp. 287

Author(s):

Maria A. Bukharinova ◽

Natalia Yu. Stozhko ◽

Elizaveta A. Novakovskaya ◽

Ekaterina I. Khamzina ◽

Aleksey V. Tarasov ◽

...

Keyword(s):

Uric Acid ◽

Electrochemical Impedance ◽

Linear Sweep Voltammetry ◽

Cost Effective ◽

Human Saliva ◽

Charge Transfer Resistance ◽

Oxidation Potential ◽

Transfer Resistance ◽

Highly Sensitive

The paper describes the development of a carbon veil-based electrode (CVE) for determining uric acid (UA) in saliva. The electrode was manufactured by lamination technology, electrochemically activated and used as a highly sensitive voltammetric sensor (CVEact). Potentiostatic polarization of the electrode at 2.0 V in H2SO4 solution resulted in a higher number of oxygen and nitrogen-containing groups on the electrode surface; lower charge transfer resistance; a 1.5 times increase in the effective surface area and a decrease in the UA oxidation potential by over 0.4 V, compared with the non-activated CVE, which was confirmed by energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, chronoamperometry and linear sweep voltammetry. The developed sensor is characterized by a low detection limit of 0.05 µM and a wide linear range (0.09–700 µM). The results suggest that the sensor has perspective applications for quick determination of UA in artificial and human saliva. RSD does not exceed 3.9%, and recovery is 96–105%. UA makes a significant contribution to the antioxidant activity (AOA) of saliva (≈60%). In addition to its high analytical characteristics, the important advantages of the proposed CVEact are the simple, scalable, and cost-effective manufacturing technology and the absence of additional complex and time-consuming modification operations.

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Impedimetric Determination of Kanamycin in Milk with Aptasensor Based on Carbon Black-Oligolactide Composite

Sensors ◽

10.3390/s20174738 ◽

2020 ◽

Vol 20 (17) ◽

pp. 4738 ◽

Cited By ~ 1

Author(s):

Tatiana Kulikova ◽

Vladimir Gorbatchuk ◽

Ivan Stoikov ◽

Alexey Rogov ◽

Gennady Evtugyn ◽

...

Keyword(s):

Carbon Black ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

3D Structure ◽

Cationic Polyelectrolyte ◽

Charge Transfer Resistance ◽

Transfer Resistance ◽

Chitosan Matrix ◽

Negative Effect

The determination of antibiotics in food is important due to their negative effect on human health related to antimicrobial resistance problem, renal toxicity, and allergic effects. We propose an impedimetric aptasensor for the determination of kanamycin A (KANA), which was assembled on the glassy carbon electrode by the deposition of carbon black in a chitosan matrix followed by carbodiimide binding of aminated aptamer mixed with oligolactide derivative of thiacalix[4]arene in a cone configuration. The assembling was monitored by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. In the presence of the KANA, the charge transfer resistance of the inner interface surprisingly decreased with the analyte concentration within 0.7 and 50 nM (limit of detection 0.3 nM). This was attributed to the partial shielding of the negative charge of the aptamer and of its support, a highly porous 3D structure of the surface layer caused by a macrocyclic core of the carrier. The use of electrostatic assembling in the presence of cationic polyelectrolyte decreased tenfold the detectable concentration of KANA. The aptasensor was successfully tested in the determination of KANA in spiked milk and yogurt with recoveries within 95% and 115%.

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An Electrochemical Immunosensor Based on a Self-Assembled Monolayer Modified Electrode for Label-Free Detection of α-Synuclein

Sensors ◽

10.3390/s20030617 ◽

2020 ◽

Vol 20 (3) ◽

pp. 617 ◽

Cited By ~ 2

Author(s):

Chuang-Ye Ge ◽

Md. Mahbubur Rahman ◽

Wei Zhang ◽

Nasrin Siraj Lopa ◽

Lei Jin ◽

...

Keyword(s):

Dynamic Range ◽

Electrochemical Impedance ◽

Charge Transfer Resistance ◽

Label Free ◽

Serum Samples ◽

Self Assembled Monolayer ◽

Electrochemical Impedance Spectra ◽

Transfer Resistance ◽

Label Free Detection ◽

Self Assembled

This research demonstrated the development of a simple, cost-effective, and label-free immunosensor for the detection of α-synuclein (α-Syn) based on a cystamine (CYS) self-assembled monolayer (SAM) decorated fluorine-doped tin oxide (FTO) electrode. CYS-SAM was formed onto the FTO electrode by the adsorption of CYS molecules through the head sulfur groups. The free amine (–NH2) groups at the tail of the CYS-SAM enabled the immobilization of anti-α-Syn-antibody, which concurrently allowed the formation of immunocomplex by covalent bonding with α-Syn-antigen. The variation of the concentrations of the attached α-Syn at the immunosensor probe induced the alternation of the current and the charge transfer resistance (Rct) for the redox response of [Fe(CN)6]3−/4−, which displayed a linear dynamic range from 10 to 1000 ng/mL with a low detection limit (S/N = 3) of ca. 3.62 and 1.13 ng/mL in differential pulse voltammetry (DPV) and electrochemical impedance spectra (EIS) measurements, respectively. The immunosensor displayed good reproducibility, anti-interference ability, and good recoveries of α-Syn detection in diluted human serum samples. The proposed immunosensor is a promising platform to detect α-Syn for the early diagnose of Parkinson’s disease, which can be extended for the determination of other biologically important biomarkers.

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Au-Pd Bimetallic Nanoparticle Electrodes for Direct Electroreduction of Hexavalent Chromium Complexes

Australian Journal of Chemistry ◽

10.1071/ch15660 ◽

2016 ◽

Vol 69 (4) ◽

pp. 423 ◽

Cited By ~ 8

Author(s):

Roozbeh Siavash Moakhar ◽

Mohiedin Bagheri Hariri ◽

Ajay Kushwaha ◽

Abolghasem Dolati ◽

Mohammad Ghorbani ◽

...

Keyword(s):

Indium Tin Oxide ◽

Electrochemical Impedance ◽

Low Cost ◽

Charge Transfer Resistance ◽

Glass Electrode ◽

Au Nanoparticle ◽

Electrochemical Technique ◽

Transfer Resistance ◽

Pd Nanoparticle ◽

Bimetallic Nanoparticle

This paper reports a simple, low-cost, and effective electrochemical technique for sensing and reducing CrVI based on a Au-Pd bimetallic nanoparticle (BNP)-decorated indium tin oxide (ITO) conducting glass electrode. It was observed that the Au-Pd BNP-decorated ITO electrode could significantly boost the electrochemical reduction of CrVI when compared with either Au nanoparticle- or Pd nanoparticle-decorated ITO electrodes. These BNP-decorated electrodes exhibited a wide linear concentration range of 0.001–100 μM, a very low detection limit (signal-to-noise ratio = 3) of 0.3 nM, and a high sensitivity of 1.701 μA μM–1. From electrochemical impedance spectroscopy, it was revealed that this significant improvement was mainly due to the reduction in the charge-transfer resistance, which leads to faster free exchange of the reaction intermediates. The proposed Au-Pd BNP electrode also demonstrated excellent stability, selectivity, repeatability, and reproducibility.

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The Experimental Verification of a Generalized Model of Equivalent Circuits

Hungarian Journal of Industry and Chemistry ◽

10.33927/hjic-2021-01 ◽

2021 ◽

Vol 49 (1) ◽

pp. 1-8

Author(s):

Zoltán Lukács ◽

Dávid Baccilieri ◽

Tamás Kristóf

Keyword(s):

Charge Transfer ◽

Electrochemical Impedance ◽

Charge Transfer Resistance ◽

Mathematical Treatment ◽

Frequency Range ◽

Transfer Resistance ◽

Generalized Model ◽

Fitting In ◽

Adsorption Desorption

The determination of typical parameters of electrochemical systems, e.g. the polarization or charge transfer resistances, can be critical with regard to the application of Electrochemical Impedance Spectroscopy (EIS) if the lower frequency range is biased as a result of transport and/or adsorption/desorption processes. In such cases, the charge transfer resistance should be assessed from the higher frequency range which is typically inadequate in itself as an input for nonlinear parameter fitting. In earlier publications, an alternative mathematical treatment of both the Equivalent Circuit (EC) and of the parameter dispersion was provided using a generalized model of ECs and also a dispersion-invariant model of the electrochemical interface. In the present work, the previously presented experimental EIS results were crosschecked to verify the performance of the generalized model against a series of redox and corrosion systems. The results proved that the applied method is consistent and provides a fairly good correlation between the principal resistance data assessed by different methods.

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