Sensitive Electrochemical Detection of Phosphorylated-Tau Threonine 231 in Human Serum Using Interdigitated Wave-Shaped Electrode

The development of an electrochemical biosensor for the detection of phosphorylated-tau threonine 231 (p-tau231), a biomarker of Alzheimer’s disease (AD), has yet to be achieved. Therefore, in this study, we developed a simple, small size, cheap, and sensitive electrochemical biosensor based on an interdigitated wave-shaped electrode via an activated self-assembled monolayer to preserve a specific anti–p-tau231 antibody (IWE/SAM/EDC-NHS/anti–p-tau231). Detection of p-tau231 in human serum (HS) using the biosensor was undertaken using electrochemical impedance spectroscopy (EIS). The change in charge-transfer resistance (Rct) in the EIS analysis of the biosensor indicated the detection of p-tau231 in HS within a wide linear range of detection (10−4–101 ng mL−1), and a low limit of detection (140 pg mL−1). This lower limit is less than the detection level of p-tau231 in cerebrospinal fluid (CSF) (700 pg mL−1) of AD patients and the level of CSF p-tau231 of patients with mild cognitive impairment (501 pg mL−1), demonstrating the possibility of using the biosensor in detection of p-tau231 at early stage AD. A high binding affinity and low dissociation constant (Kd) between anti–p-tau231 and p-tau231 in HS was demonstrated by using a biosensor and Kd was 7.6 pM, demonstrating the high specific detection of p-tau231 by the biosensor. The good selectivity of the biosensor for the detection of p-tau231 with differential analytes was also examined in this study.

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Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Sensors ◽

10.3390/s21061929 ◽

2021 ◽

Vol 21 (6) ◽

pp. 1929

Author(s):

Alexander Rodríguez ◽

Francisco Burgos-Flórez ◽

José D. Posada ◽

Eliana Cervera ◽

Valtencir Zucolotto ◽

...

Keyword(s):

Frequency Analysis ◽

Surface Characterization ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Neuronal Damage ◽

Charge Transfer Resistance ◽

Single Frequency ◽

Response Analysis ◽

Transfer Resistance ◽

Therapeutic Decisions

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

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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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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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Fabrication of an Electrochemical Aptasensor Composed of Multifunctional DNA Three-Way Junction on Au Microgap Electrode for Interferon Gamma Detection in Human Serum

Biomedicines ◽

10.3390/biomedicines9060692 ◽

2021 ◽

Vol 9 (6) ◽

pp. 692

Author(s):

Seungwoo Noh ◽

Jinmyeong Kim ◽

Chulhwan Park ◽

Junhong Min ◽

Taek Lee

Keyword(s):

Human Serum ◽

Interferon Gamma ◽

Electrochemical Biosensor ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Polyacrylamide Gel Electrophoresis ◽

Thiol Group ◽

Clinical Test ◽

Serum Samples ◽

Ifn Γ

Interferon gamma (IFN-γ) is an important cytokine with antiviral, antibacterial, and immunosuppressive properties. It has been used as a biomarker for the early detection of several diseases, including cancer, human immunodeficiency virus (HIV), tuberculosis, and paratuberculosis. In this study, we developed an electrochemical biosensor composed of multifunctional DNA 3WJ to detect IFN-γ level with high sensitivity. Each multifunctional triple-stranded aptamer (MF-3WJ) was designed to have an IFN-γ aptamer sequence, anchoring region (thiol group), and 4C–C (cytosine–cytosine) mismatch sequence (signal generation), which could introduce silver ions. To generate the electrochemical signal, four Ag+ ions were intercalated (3wj b-3wj c) in the 4C–C mismatch sequence. MF-3WJ was assembled through the annealing step, and the assembly of MF-3WJ was confirmed by 8% tris–boric–EDTA native polyacrylamide gel electrophoresis. The Au microgap electrode was manufactured to load sample volumes of 5 µL. The reliability of electrochemical biosensor measurement was established by enabling the measurement of seven samples from one Au microgap electrode. MF-3WJ was immobilized on the Au microgap electrode. Then, cyclic voltammetry and electrochemical impedance spectroscopy were performed to confirm the electrochemical properties of MF-3WJ. To test the electrochemical biosensor’s ability to detect IFN-γ, the limit of detection (LOD) and selectivity tests were performed by square wave voltammetry. A linear region was observed in the concentration range of 1 pg/mL–10 ng/mL of IFN-γ. The LOD of the fabricated electrochemical biosensor was 0.67 pg/mL. In addition, for the clinical test, the LOD test was carried out for IFN-γ diluted in 10% human serum samples in the concentration range of 1 pg/mL–10 ng/mL, and the LOD was obtained at 0.42 pg/mL.

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Label-Free Electrochemical Detection of S. mutans Exploiting Commercially Fabricated Printed Circuit Board Sensing Electrodes

Micromachines ◽

10.3390/mi10090575 ◽

2019 ◽

Vol 10 (9) ◽

pp. 575 ◽

Cited By ~ 5

Author(s):

Gorachand Dutta ◽

Abdoulie A. Jallow ◽

Debjani Paul ◽

Despina Moschou

Keyword(s):

Electrochemical Detection ◽

Printed Circuit Board ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Charge Transfer Resistance ◽

Circuit Board ◽

Label Free ◽

Electrochemical Impedance Spectra ◽

Transfer Resistance ◽

Printed Circuit

This paper reports for the first time printed-circuit-board (PCB)-based label-free electrochemical detection of bacteria. The demonstrated immunosensor was implemented on a PCB sensing platform which was designed and fabricated in a standard PCB manufacturing facility. Bacteria were directly captured on the PCB sensing surface using a specific, pre-immobilized antibody. Electrochemical impedance spectra (EIS) were recorded and used to extract the charge transfer resistance (Rct) value for the different bacteria concentrations under investigation. As a proof-of-concept, Streptococcus mutans (S. mutans) bacteria were quantified in a phosphate buffered saline (PBS) buffer, achieving a limit of detection of 103 CFU/mL. Therefore, the proposed biosensor is an attractive candidate for the development of a simple and robust point-of-care diagnostic platform for bacteria identification, exhibiting good sensitivity, high selectivity, and excellent reproducibility.

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Electrochemical Immunosensor for the Early Detection of Rheumatoid Arthritis Biomarker: Anti-Cyclic Citrullinated Peptide Antibody in Human Serum Based on Avidin-Biotin System

Sensors ◽

10.3390/s21010124 ◽

2020 ◽

Vol 21 (1) ◽

pp. 124

Author(s):

Somasekhar R. Chinnadayyala ◽

Sungbo Cho

Keyword(s):

Rheumatoid Arthritis ◽

Human Serum ◽

Microelectrode Array ◽

Microelectromechanical Systems ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Transfer Resistance ◽

Relative Standard ◽

Modified Ice ◽

Hands And Feet

Rheumatoid arthritis (RA) is a chronic autoimmune disease that produces a progressive inflammatory response that leads to severe pain, swelling, and stiffness in the joints of hands and feet, followed by irreversible damage of the joints. The authors developed a miniaturized, label-free electrochemical impedimetric immunosensor for the sensitive and direct detection of arthritis Anti-CCP-ab biomarker. An interdigitated-chain-shaped microelectrode array (ICE) was fabricated by taking the advantage of microelectromechanical systems. The fabricated ICE was modified with a self-assembled monolayer (SAM) of Mercaptohexanoic acid (MHA) for immobilization of the synthetic peptide bio-receptor (B-CCP). The B-CCP was attached onto the surface of SAM modified ICE through a strong avidin-biotin bio-recognition system. The modified ICE surface with the SAM and bio-molecules (Avidin, B-CCP, Anti-CCP-ab and BSA) was morphologically and electrochemically characterized. The change in the sensor signal upon analyte binding on the electrode surface was probed through the electrochemical impedance spectroscopy (EIS) property of charge-transfer resistance (Rct) of the modified electrodes. EIS measurements were target specific and the sensor response was linearly increased with step wise increase in target analyte (Anti-CCP-ab) concentrations. The developed sensor showed a linear range for the addition of Anti-CCP-ab between 1 IU mL−1 → 800 IU mL−1 in phosphate buffered saline (PBS) and Human serum (HS), respectively. The sensor showed a limit of detection of 0.60 IU mL−1 and 0.82 IU mL−1 in the PBS and HS, respectively. The develop bio-electrode showed a good reproducibility (relative standard deviation (RSD), 1.52%), selectivity and stability (1.5% lost at the end of 20th day) with an acceptable recovery rate (98.0% → 101.18%) and % RSD’s for the detection of Anti-CCP-ab in spiked HS samples.

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Electrochemical DNA Sensor Based on the Copolymer of Proflavine and Azure B for Doxorubicin Determination

Nanomaterials ◽

10.3390/nano10050924 ◽

2020 ◽

Vol 10 (5) ◽

pp. 924

Author(s):

Anna Porfireva ◽

Gennady Evtugyn

Keyword(s):

Polymer Film ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Polymer Surface ◽

Charge Transfer Resistance ◽

Dna Sensor ◽

Transfer Resistance ◽

Redox Probe ◽

Azure B

A DNA sensor has been developed for the determination of doxorubicin by consecutive electropolymerization of an equimolar mixture of Azure B and proflavine and adsorption of native DNA from salmon sperm on a polymer film. Electrochemical investigation showed a difference in the behavior of individual drugs polymerized and their mixture. The use of the copolymer offered some advantages, i.e., a higher roughness of the surface, a wider range of the pH sensitivity of the response, a denser and more robust film, etc. The formation of the polymer film and its redox properties were studied using scanning electron microscopy and electrochemical impedance spectroscopy. For the doxorubicin determination, its solution was mixed with DNA and applied on the polymer surface. After that, charge transfer resistance was assessed in the presence of [Fe(CN)6]3−/4− as the redox probe. Its value regularly grew with the doxorubicin concentration in the range from 0.03 to 10 nM (limit of detection 0.01 nM). The DNA sensor was tested on the doxorubicin preparations and spiked samples mimicking blood serum. The recovery was found to be 98–106%. The DNA sensor developed can find application for the determination of drug residues in blood and for the pharmacokinetics studies.

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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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Influence of HAP on the Morpho-Structural Properties and Corrosion Resistance of ZrO2-Based Composites for Biomedical Applications

Crystals ◽

10.3390/cryst11020202 ◽

2021 ◽

Vol 11 (2) ◽

pp. 202

Author(s):

Réka Barabás ◽

Carmen Ioana Fort ◽

Graziella Liana Turdean ◽

Liliana Bizo

Keyword(s):

Electrochemical Impedance ◽

Artificial Saliva ◽

Synergetic Effect ◽

Composite Layer ◽

Charge Transfer Resistance ◽

Processing Route ◽

Dental Alloys ◽

Metallic Electrode ◽

Transfer Resistance ◽

X Ray

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synergetic effect between the diffusion process through the Chit-composite layer and the roughness of the metallic electrode surface.

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