MoS2/PPy Nanocomposite as a Transducer for Electrochemical Aptasensor of Ampicillin in River Water

We report the design of an electrochemical aptasensor for ampicillin detection, which is an antibiotic widely used in agriculture and considered to be a water contaminant. We studied the transducing potential of nanostructure composed of MoS2 nanosheets and conductive polypyrrole nanoparticles (PPyNPs) cast on a screen-printed electrode. Fine chemistry is developed to build the biosensors entirely based on robust covalent immobilizations of naphthoquinone as a redox marker and the aptamer. The structural and morphological properties of the nanocomposite were studied by SEM, AFM, and FT-IR. High-resolution XPS measurements demonstrated the formation of a binding between the two nanomaterials and energy transfer affording the formation of heterostructure. Cyclic voltammetry and electrochemical impedance spectroscopy were used to analyze their electrocatalytic properties. We demonstrated that the nanocomposite formed with PPyNPs and MoS2 nanosheets has electro-catalytic properties and conductivity leading to a synergetic effect on the electrochemical redox process of the redox marker. Thus, a highly sensitive redox process was obtained that could follow the recognition process between the apatamer and the target. An amperometric variation of the naphthoquinone response was obtained regarding the ampicillin concentration with a limit of detection (LOD) of 10 pg/L (0.28 pM). A high selectivity towards other contaminants was demonstrated with this biosensor and the analysis of real river water samples without any treatment showed good recovery results thanks to the antifouling properties. This biosensor can be considered a promising device for the detection of antibiotics in the environment as a point-of-use system.

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Folding-Based Electrochemical Aptasensor for the Determination of β-Lactoglobulin on Poly-L-Lysine Modified Graphite Electrodes

Sensors ◽

10.3390/s20082349 ◽

2020 ◽

Vol 20 (8) ◽

pp. 2349

Author(s):

Olaya Amor-Gutiérrez ◽

Giulia Selvolini ◽

M. Teresa Fernández-Abedul ◽

Alfredo de la Escosura-Muñiz ◽

Giovanna Marrazza

Keyword(s):

Limit Of Detection ◽

Low Cost ◽

Food Samples ◽

Electrochemical Aptasensor ◽

Point Of Use ◽

Important Health ◽

Broad Variety ◽

Important Health Issue ◽

Β Lactoglobulin

Nowadays, food allergy is a very important health issue, causing adverse reactions of the immune system when exposed to different allergens present in food. Because of this, the development of point-of-use devices using miniaturized, user-friendly, and low-cost instrumentation has become of outstanding importance. According to this, electrochemical aptasensors have been demonstrated as useful tools to quantify a broad variety of targets. In this work, we develop a simple methodology for the determination of β-lactoglobulin (β-LG) in food samples using a folding-based electrochemical aptasensor built on poly-L-lysine modified graphite screen-printed electrodes (GSPEs) and an anti-β-lactoglobulin aptamer tagged with methylene blue (MB). This aptamer changes its conformation when the sample contains β-LG, and due to this, the spacing between MB and the electrode surface (and therefore the electron transfer efficiency) also changes. The response of this biosensor was linear for concentrations of β-LG within the range 0.1–10 ng·mL−1, with a limit of detection of 0.09 ng·mL−1. The biosensor was satisfactorily employed for the determination of spiked β-LG in real food samples.

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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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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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Immobilization-Free Electrochemical Sensor Coupled with a Graphene-Oxide-Based Aptasensor for Glycated Albumin Detection

Biosensors ◽

10.3390/bios11030085 ◽

2021 ◽

Vol 11 (3) ◽

pp. 85

Author(s):

Wassa Waiwinya ◽

Thitirat Putnin ◽

Dechnarong Pimalai ◽

Wireeya Chawjiraphan ◽

Nuankanya Sathirapongsasuti ◽

...

Keyword(s):

Graphene Oxide ◽

Electrochemical Sensor ◽

Detection Method ◽

Limit Of Detection ◽

Glycated Albumin ◽

Cost Effective ◽

Logarithmic Scale ◽

Electrochemical Aptasensor ◽

Alternative Approach

An immobilization-free electrochemical sensor coupled with a graphene oxide (GO)-based aptasensor was developed for glycated human serum albumin (GHSA) detection. The concentration of GHSA was monitored by measuring the electrochemical response of free GO and aptamer-bound GO in the presence of glycated albumin; their currents served as the analytical signals. The electrochemical aptasensor exhibited good performance with a base-10 logarithmic scale. The calibration curve was achieved in the range of 0.01–50 µg/mL. The limit of detection (LOD) was 8.70 ng/mL. The developed method was considered a one-drop measurement process because a fabrication step and the probe-immobilization process were not required. This simple sensor offers a cost-effective, rapid, and sensitive detection method, and could be an alternative approach for determination of GHSA levels.

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Supramolecular assemblies of carbon nanocoils and tetraphenylporphyrin derivatives for sensing of catechol and hydroquinone in aqueous solution

Scientific Reports ◽

10.1038/s41598-021-84294-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Syeda Aqsa Batool Bukhari ◽

Habib Nasir ◽

Lujun Pan ◽

Mehroz Tasawar ◽

Manzar Sohail ◽

...

Keyword(s):

Electrochemical Impedance ◽

Limit Of Detection ◽

Linear Trend ◽

Differential Pulse ◽

Peak Potential ◽

Limit Of Quantification ◽

Efficient Detection ◽

Good Repeatability ◽

Ft Ir ◽

Pulse Voltammetry

AbstractNon-enzymatic electrochemical detection of catechol (CC) and hydroquinone (HQ), the xenobiotic pollutants, was carried out at the surface of novel carbon nanocoils/zinc-tetraphenylporphyrin (CNCs/Zn-TPP) nanocomposite supported on glassy carbon electrode. The synergistic effect of chemoresponsive activity of Zn-TPP and a large surface area and electron transfer ability of CNCs lead to efficient detection of CC and HQ. The nanocomposite was characterized by using FT-IR, UV/vis. spectrophotometer, SEM and energy dispersive X-ray spectroscopy (EDS). Cyclic voltammetry, differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy were used for the electrochemical studies. CNCs/Zn-TPP/GCE nanosensor displayed a limit of detection (LOD), limit of quantification (LOQ) and sensitivity for catechol as 0.9 µM, 3.1 µM and 0.48 µA µM−1 cm−2, respectively in a concentration range of 25–1500 µM. Similarly, a linear trend in the concentration of hydroquinone detection was observed between 25 and 1500 µM with an LOD, LOQ and sensitivity of 1.5 µM, 5.1 µM and 0.35 µA µM−1 cm−2, respectively. DPV of binary mixture pictured well resolved peaks with anodic peak potential difference, ∆Epa(CC-HQ), of 110 mV showing efficient sensing of CC and HQ. The developed nanosensor exhibits stability for up to 30 days, better selectivity and good repeatability for eight measurements (4.5% for CC and 5.4% for HQ).

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An Electrochemical Sensor Based On Graphite Electrode Modified With Silica Containing 1-N-Propyl-3-Methylimidazolium Species For Determination Of Ascorbic Acid

METHODS AND OBJECTS OF CHEMICAL ANALYSIS ◽

10.17721/moca.2019.5-14 ◽

2019 ◽

Vol Vol. 14, No.1 ◽

pp. 5-14 ◽

Cited By ~ 1

Author(s):

Anastasiya Tkachenko ◽

Mykyta Onizhuk ◽

Oleg Tkachenko ◽

Leliz T. Arenas ◽

Edilson V. Benvenutt ◽

...

Keyword(s):

Ascorbic Acid ◽

Cyclic Voltammetry ◽

Electrochemical Sensor ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Pharmaceutical Formulations ◽

Differential Pulse ◽

Long Term Stability ◽

Diffusion Limited

In the present study, an electrochemical sensor based on the electrode (SiMImCl/C) consisting of graphite and silica, grafted with 1-n-propyl-3-methylimidazolium chloride was used for ascorbic acid (AA) quantification in pharmaceuticals and food formulations. Cyclic voltammetry and electrochemical impedance spectroscopy were applied for electrochemical characterization of the SiMImCl/C electrode. The cyclic voltammetry study revealed that the oxidation of AA on this electrode is an irreversible process, realized by adsorption and diffusion limited step. The differential pulse voltammetry was applied to develop a procedure for the AA determination. The linear range was found to be 0.3–170 μmol L-1 and the limit of detection – 0.1 μmol L-1. The proposed SiMImCl/C electrode has long term stability and does not show electrochemical activity towards the analytes, which commonly coexist with AA. The sensor was successfully used for quantification of AA in food and pharmaceutical formulations.

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ELIMINASI GANGGUAN MATRIKS DALAM ANALISIS MERKURI HG SEBAGAI SENYAWA KOMPLEKS THIO MICHLER’S KETON SECARA SPEKTROFOTOMETRI

JURNAL PIJAR MIPA ◽

10.29303/jpm.v11i1.2 ◽

2016 ◽

Vol 11 (1) ◽

Author(s):

Sukib Sukib ◽

Muti'ah Muti'ah

Keyword(s):

Solvent Extraction ◽

River Water ◽

Complex Compound ◽

Limit Of Detection ◽

Standard Addition ◽

Analysis Method ◽

Addition Method ◽

Matrix Interferences ◽

Mercury Analysis

Abstrak. Telah dilakukan penelitian tentang penyusunan metode analisis merkuri melalui pembentukan senyawa kompleks dengan 4,4'-Bis(dimethylamino)thio-benzophenone TMK. Senyawa kompleks tersebut berwarna biru kehijauan yang dapat dideteksi dengan spektrofoto-meter pada kondisi: lmax 574 nm; pH 3; konsentrasi TMK 0,0002 M, dan waktu tunggu selama 4–10 menit. perbandingan volume pereaksi: Hg(II), bufer pH 3, TMK 0,002 M, H2O bebas ion adalah 1:1:1:7. Dari hasil penelitian menunjukkan bahwa metode ini telah memenuhi validitas, yaitu: linieritas 0,05–2,0 mg/L, limit deteksi 0,008 mg/L, dan % recovery antara 98% – 102%. Gangguan matriks akibat adanya ion–ion Au(III), Ag(I), Pd(II), Cu(II), Co(II), dan Fe(II) dapat dieliminasi dengan metode ekstraksi pelarut dan adisi standar. Metode adisi standar terbukti mampu memberikan data hasil pengukuran yang dapat dipercaya pada a 5%, yaitu untuk sampel buatan sebesar (0,053 ± 0,001) mg/L, air sungai (0,034 ± 0,004) mg/L, dan sedimen sebesar (4,172 ± 0,050) mg/kg. Dari hasil penelitian ini dapat disimpulkan bahwa metode ekstraksi pelarut dan adisi standar mampu mengeliminasi gangguan matriks pada analisis merkuri sebagai kompleks Hg-TMK secara spektrofotometriKata kunci: Metode analisis merkuri, Thio Michler’s keton, eliminasi, gangguan matriks Abstract. A research of analysis method for determination of mercury through formation of complex with 4,4'-bis(dimethylamino)thiobenzophenone TMK has been conducted. The green blue complex compound can be detected with spectrophoto-meter in conditions: lmax 574 nm, buffer acetate pH 3, concentration of TMK 0,0002 M, and the absorbance of complex remains stable for 4–10 minutes. The formula of reagents volume for: Hg(II): buffer acetate pH 3: TMK 0,002 M : de-ionized water is 1:1:1:7. This method is valid, with parameters such as linearity 0.05–2.00 mg/L, limit of detection 0.008 mg/L, and recovery in the range 98%-102%. Matrix interferences that are caused by Au(III), Ag(I), Pd(II), Cu(II), Co(II), and Fe(III) ions can be eliminated with solvent extraction and standard addition methods. Standard addition method is able to give data of trusty measurement result at a 5%, that is for synthesis sample as (0.053 ± 0.001) mg/L, river water (0.034 ± 0.004) mg/L, and for sediment (4.172 ± 0.050) mg/kg. From the result of this research, it can be concluded that solvent extraction and standard addition methods are able to eliminated matrix interferences in mercury analysis as Hg-TMK complex spectrophotometrically Key waords: mercury analysis method, Thio Michler’s ketone, elimination, matrix interferences

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Portable Data Acquisition System for Nano and Ultra-Micro Scale Electrochemical Sensors

10.26434/chemrxiv.12320291 ◽

2020 ◽

Author(s):

Alan O'Riordan ◽

Ian Seymour ◽

Aidan Murphy ◽

Ivan O'Connell

Keyword(s):

Data Acquisition ◽

River Water ◽

Electrochemical Sensors ◽

Full Range ◽

Data Acquisition System ◽

Water Quality Monitoring ◽

Electrochemical Sensing ◽

Acquisition System ◽

Micro Scale ◽

Point Of Use

This work describes a flexible and portable data acquisition system that has been developed to interface to nano and ultra-micro scale electrochemical sensors at the point of use. It can perform a range of voltammetric tests, including Cyclic Voltammetry, Square Wave Voltammetry and Generator Collector Voltammetery. The data acquisition system interfaces to a smartphone, operates from a rechargeable battery and is of suitable form factor to ensure that it’s fully portable. By utilising commercially available components, this system has been developed to lower the barrier for entry for the development of emerging portable electrochemical sensing technologies at micro and nano scale. To show the full range of functionality of the system, a use case involving river water quality monitoring is presented through generation of a calibration curve, using a recently developed Tyndall National Institute ultra-microband electrochemical sensor, for the detection of dissolved oxygen in river water.

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Highly sensitive dual mode electrochemical platform for microRNA detection

Scientific Reports ◽

10.1038/srep36719 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 38

Author(s):

Pawan Jolly ◽

Marina R. Batistuti ◽

Anna Miodek ◽

Pavel Zhurauski ◽

Marcelo Mulato ◽

...

Keyword(s):

Nucleic Acids ◽

Dynamic Range ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Dual Mode ◽

Electrode Surfaces ◽

Microrna Detection ◽

Highly Sensitive ◽

Detection Mode ◽

Amplification Strategy

Abstract MicroRNAs (miRNAs) play crucial regulatory roles in various human diseases including cancer, making them promising biomarkers. However, given the low levels of miRNAs present in blood, their use as cancer biomarkers requires the development of simple and effective analytical methods. Herein, we report the development of a highly sensitive dual mode electrochemical platform for the detection of microRNAs. The platform was developed using peptide nucleic acids as probes on gold electrode surfaces to capture target miRNAs. A simple amplification strategy using gold nanoparticles has been employed exploiting the inherent charges of the nucleic acids. Electrochemical impedance spectroscopy was used to monitor the changes in capacitance upon any binding event, without the need for any redox markers. By using thiolated ferrocene, a complementary detection mode on the same sensor was developed where the increasing peaks of ferrocene were recorded using square wave voltammetry with increasing miRNA concentration. This dual-mode approach allows detection of miRNA with a limit of detection of 0.37 fM and a wide dynamic range from 1 fM to 100 nM along with clear distinction from mismatched target miRNA sequences. The electrochemical platform developed can be easily expanded to other miRNA/DNA detection along with the development of microarray platforms.

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Encapsulation of hemin in Fe-based metal-organic frameworks and its application for the direct determination of aflatoxin M1

World Mycotoxin Journal ◽

10.3920/wmj2020.2578 ◽

2021 ◽

pp. 1-10

Author(s):

F. Jahangiri-Dehaghani ◽

H.R. Zare ◽

Z. Shekari

Keyword(s):

Electrochemical Impedance ◽

Metal Organic Frameworks ◽

Direct Determination ◽

Differential Pulse ◽

Aflatoxin M1 ◽

Label Free ◽

Electrochemical Aptasensor ◽

Selective Determination ◽

Metal Organic

A label-free electrochemical aptasensor was constructed for the sensitive and selective determination of AFM1. For preparation of the aptasensor, the AFM1 aptamer was immobilised on the surface of a glassy carbon electrode modified with hemin encapsulated in Fe-based metal-organic frameworks (hemin@Fe-MIL-101). The morphology and the structure of Fe-MIL-101 and hemin@Fe-MIL-101 were evaluated by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction and Brunauer-Emmett-Teller-N2 sorption methods. Electrochemical impedance spectroscopy and cyclic voltammetry were performed to monitor the fabrication process of the electrochemical aptasensor. The electrochemical reduction current of hemin encapsulated in Fe-MIL-101 serves as a signal for the quantitative determination of AFM1. Differential pulse voltammetry was done to determine the AFM1 concentration in the linear range of 1.0×10-1-100.0 ng/ml. The detection limit of AFM1 was estimated to be 4.6×10-2 ng/ml. Finally, the fabricated aptasensor was applied to determine AFM1 in raw and boiled milk samples.

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