scholarly journals Graphene Quantum Dots and Cu(I) Liquid Crystal for Advanced Electrochemical Detection of Doxorubicine in Aqueous Solutions

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2788
Author(s):  
Sorina Motoc Ilies ◽  
Bianca Schinteie ◽  
Aniela Pop ◽  
Sorina Negrea ◽  
Carmen Cretu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Aqueous Solutions ◽  
Liquid Crystalline ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Differential Pulse ◽  
Trace Concentration ◽  
Detection Stage ◽  
Pulse Voltammetry ◽  
Concentration Levels

Two paste electrodes based on graphene quantum dots and carbon nanotubes (GRQD/CNT) and one modified with a homoleptic liquid crystalline Cu(I) based coordination complex (Cu/GRQD/CNT) were obtained and morphostructurally and electrochemically characterized in comparison with simple CNT electrode (CNT) for doxorubicine (DOX) detection in aqueous solutions. GRQD/CNT showed the best electroanalytical performance by differential pulse voltammetry technique (DPV). Moreover, applying a preconcentration step prior to detection stage, the lowest limit of detection (1 ng/L) and the highest sensitivity (216,105 µA/mgL−1) in comparison with reported literature data were obtained. Cu/GRQD/CNT showed good results using multiple pulse amperometry technique (MPA) and a favorable shifting of the potential detection to mitigate potential interferences. Both GRQD-based paste electrodes have a great potential for practical utility in DOX determination in water at trace concentration levels, using GRQD/CNT with DPV and in pharmaceuticals formulations using Cu/GRQD/CNT with MPA.

scholarly journals An efficient electrochemical sensing of hazardous catechol and hydroquinone at direct green 6 decorated carbon paste electrode

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
K. Chetankumar ◽  
B. E. Kumara Swamy ◽  
S. C. Sharma ◽  
S. A. Hariprasad
Keyword(s):  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Tap Water ◽  
Differential Pulse ◽  
Electrochemical Sensing ◽  
Carbon Paste ◽  
Pulse Voltammetry ◽  
Two Peaks ◽  
Paste Electrode ◽  
Scanning Electron

AbstractIn this proposed work, direct green 6 (DG6) decorated carbon paste electrode (CPE) was fabricated for the efficient simultaneous and individual sensing of catechol (CA) and hydroquinone (HY). Electrochemical deeds of the CA and HY were carried out by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at poly-DG6-modfied carbon paste electrode (Po-DG6-MCPE). Using scanning electron microscopy (SEM) studied the surface property of unmodified CPE (UCPE) and Po-DG6-MCPE. The decorated sensor displayed admirable electrocatalytic performance with fine stability, reproducibility, selectivity, low limit of detection (LLOD) for HY (0.11 μM) and CC (0.09 μM) and sensor process was originated to be adsorption-controlled phenomena. The Po-DG6-MCPE sensor exhibits well separated two peaks for HY and CA in CV and DPV analysis with potential difference of 0.098 V. Subsequently, the sensor was practically applied for the analysis in tap water and it consistent in-between for CA 93.25–100.16% and for HY 97.25–99.87% respectively.

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

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).

scholarly journals Conjugation of Carboxylated Graphene Quantum Dots with Cecropin P1 for Bacterial Biosensing Applications

2020 ◽  
Author(s):  
Jonathan Bruce ◽  
Jude Clapper
Keyword(s):  
Quantum Dots ◽  
Structural Modification ◽  
Light Emission ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Strong Light ◽  
E Coli ◽  
Cecropin P1 ◽  
Compact Field ◽  
Test Kit

<p>Quantum dots have proven to be strong candidates for biosensing applications in recent years, due to their strong light emission properties and their ability to be modified with a variety of functional groups for the detection of different analytes. Here, we investigate the use of conjugated carboxylated graphene quantum dots (CGQDs) for the detection of <i>E. coli</i>, using a biosensing procedure that focuses on measuring changes in fluorescence quenching. We have also further developed this biosensing assay into a compact, field-deployable test kit focused on rapidly measuring changes in absorbance to determine bacterial concentration. Our CGQDs were conjugated with cecropin P1, a naturally-produced antibacterial peptide that facilitates the attachment of CGQDs to <i>E. coli</i> cells. We also confirm the structural modification of these conjugated CGQDs in addition to analyzing their optical characteristics. Our findings have the potential to be used in situations where rapid, reliable detection of bacteria in liquids, such as drinking water, is required, especially given our biosensor’s relatively low observed limit of detection (LOD).</p><br>

scholarly journals Electrochemical Nanocomposite Single-Use Sensor for Dopamine Detection

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3097 ◽  
Author(s):  
Giulia Selvolini ◽  
Cinzia Lazzarini ◽  
Giovanna Marrazza
Keyword(s):  
Limit Of Detection ◽  
Differential Pulse ◽  
Sensor Response ◽  
Sensor Surface ◽  
Serum Samples ◽  
Dopamine Detection ◽  
Sensitive Sensor ◽  
Single Use ◽  
Pulse Voltammetry ◽  
Nanocomposite Sensor

In this work, we report the development of a simple and sensitive sensor based on graphite screen-printed electrodes (GSPEs) modified by a nanocomposite film for dopamine (DA) detection. The sensor was realized by electrodepositing polyaniline (PANI) and gold nanoparticles (AuNPs) onto the graphite working electrode. The sensor surface was fully characterized by means of the cyclic voltammetry (CV) technique using [Fe(CN)6]4−/3− and [Ru(NH3)6]2+/3+ as redox probes. The electrochemical behavior of the nanocomposite sensor towards DA oxidation was assessed by differential pulse voltammetry (DPV) in phosphate buffer saline at physiological pH. The sensor response was found to be linearly related to DA concentration in the range 1–100 μM DA, with a limit of detection of 0.86 μM. The performance of the sensor in terms of reproducibility and selectivity was also studied. Finally, the sensor was successfully applied for a preliminary DA determination in human serum samples.

scholarly journals Development of a Label-Free Electrochemical Aptasensor for the Detection of Tau381 and its Preliminary Application in AD and Non-AD Patients’ Sera

Biosensors ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 84 ◽  
Author(s):  
Dan Tao ◽  
Bingqing Shui ◽  
Yingying Gu ◽  
Jing Cheng ◽  
Weiying Zhang ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Early Stage ◽  
Differential Pulse ◽  
Electrical Signal ◽  
Label Free ◽  
Modified Glassy Carbon Electrode ◽  
Serum Samples ◽  
Pulse Voltammetry ◽  
Aptamer Sensor ◽  
Preliminary Application

The electrochemical aptamer sensor has been designed for detecting tau381, a critical biomarker of Alzheimer′s disease in human serum. The aptasensor is obtained by immobilizing the aptamer on a carboxyl graphene/thionin/gold nanoparticle modified glassy-carbon electrode. As a probe and bridge molecule, thionin connected carboxyl graphene and gold nanoparticles, and gave the electrical signal. Under optimal conditions, the increment of differential pulse voltammetry signal increased linearly with the logarithm of tau381 concentration in the range from 1.0 pM to 100 pM, and limit of detection was 0.70 pM. The aptasensor reliability was evaluated by determining its selectivity, reproducibility, stability, detection limit, and recovery. Performance analysis of the tau381 aptasensor in 10 patients’ serum samples showed that the aptasensor could screen patients with and without Alzheimer′s disease. The proposed aptasensor has potential for use in clinically diagnosing Alzheimer′s disease in the early stage.

Sensitive Determination of Epinephrine in the Presence of Ascorbic Acid at Poly(diphenylamine sulfonic acid) Modified Sensor

2020 ◽  
Vol 18 (4) ◽  
pp. 253-258
Author(s):  
Gamze Erdoğdu
Keyword(s):  
Ascorbic Acid ◽  
Sulfonic Acid ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Differential Pulse ◽  
Buffer Solution ◽  
Sensitive Determination ◽  
Pulse Voltammetry ◽  
Modified Sensor

A sensitive and simple modified sensor was prepared by electrodeposition of diphenylamine sulfonic acid (DPSA) to the glassy carbon electrode surface by cyclic voltammetry (CV) technique. The electrooxidation of epinephrine (EP) was accomplished by CV and differential pulse voltammetry at poly(DPSA) modified sensor. As a result of the findings, the current values were enhanced and both substances were separated at the modified sensor compared to the bare electrode. There was linearly between the oxidation current and concentration of EP from 0.2 to 100 μM in phosphate buffer solution at pH 7.0. The limit of detection was 5.0 nM and the sensitivity was 0.4205 μA/μM. The determination of EP was successfully and satisfactorily carried out in real samples such as human blood serum and urine at the poly(DPSA) sensor. To the best knowledge of this work, this is the first study that detect the EP in the presence of ascorbic acid at poly(DPSA) sensor in the literature.

scholarly journals One-Step Preparation of Nitrogen-Doped Graphene Quantum Dots With Anodic Electrochemiluminescence for Sensitive Detection of Hydrogen Peroxide and Glucose

2021 ◽  
Vol 9 ◽  
Author(s):  
Zheng Yanyan ◽  
Jing Lin ◽  
Liuhong Xie ◽  
Hongliang Tang ◽  
Kailong Wang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Quantum Dots ◽  
Limit Of Detection ◽  
Hydrothermal Process ◽  
Graphene Quantum Dots ◽  
Sensitive Detection ◽  
Uniform Size ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
One Step

Simple and efficient synthesis of graphene quantum dots (GQDs) with anodic electrochemiluminescence (ECL) remains a great challenge. Herein, we present an anodic ECL-sensing platform based on nitrogen-doped GQDs (N-GQDs), which enables sensitive detection of hydrogen peroxide (H2O2) and glucose. N-GQDs are easily prepared using one-step molecular fusion between carbon precursor and a dopant in an alkaline hydrothermal process. The synthesis is simple, green, and has high production yield. The as-prepared N-GQDs exhibit a single graphene-layered structure, uniform size, and good crystalline. In the presence of H2O2, N-GQDs possess high anodic ECL activity owing to the functional hydrazide groups. With N-GQDs being ECL probes, sensitive detection of H2O2 in the range of 0.3–100.0 μM with a limit of detection or LOD of 63 nM is achieved. As the oxidation of glucose catalyzed by glucose oxidase (GOx) produces H2O2, sensitive detection of glucose is also realized in the range of 0.7–90.0 μM (LOD of 96 nM).

scholarly journals Fluorescent Nanosensor based on Molecularly Imprinted Polymers Coated on Graphene Quantum Dots for Fast Detection of Antibiotics

2018 ◽  
Author(s):  
Tongchang Zhou ◽  
Arnab Halder ◽  
Yi Sun
Keyword(s):  
Quantum Dots ◽  
Fluorescence Intensity ◽  
Molecularly Imprinted Polymers ◽  
Limit Of Detection ◽  
Sol Gel ◽  
Graphene Quantum Dots ◽  
Carboxyl Groups ◽  
One Pot ◽  
Molecularly Imprinted ◽  
Imprinted Polymers

In this work, we firstly explored a mild, clean, and highly efficient approach for the synthesis of graphene quantum dots (GQDs). GQDs with carboxyl groups or amino groups, were prepared from one-pot environmentally friendly method assisted by hydrogen peroxide, respectively. It was proved that carboxyl groups played an important role in the fluorescence quenching. Based on these findings, we developed a novel fluorescent nanosensor by combining molecularly imprinted polymers (MIPs) with carboxyl functionalized GQDs for the determination of tetracycline (TC) in aqueous samples. The nanocomposite was prepared using a sol-gel process. GQDs-MIPs showed strong fluorescent emission at 410 nm when excited at 360 nm, which was subsequently quenched in the presence of TC. Under optimum conditions, the fluorescence intensity of GQDs-MIPs decreased in response to the increase of TC concentration with good linearity rage of 1.0-104 &micro;g L-1. The limit of detection was determined to be 1 &micro;g L-1. The fluorescence intensity of GQDs-MIPs was more strongly quenched by TC compared to the corresponding non-imprinted polymers, GQDs-NIPs. With the high sensitivity, the material was also successfully worked for the detection of TC in real spiked milk samples.

scholarly journals Electrocatalytic determination of levodopa in presence of cabergoline using carbon paste electrode modified with graphene quantum dots/2-chlorobenzoyl ferrocene/ionic liquid

2021 ◽  
Author(s):  
Peyman Mohammadzadeh Jahani
Keyword(s):  
Quantum Dots ◽  
Ionic Liquid ◽  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Simultaneous Detection ◽  
Phosphate Buffer Solution ◽  
Carbon Paste ◽  
Paste Electrode

The electrochemical sensor was fabricated for the simultaneous determination of levodopa and cabergoline using carbon paste electrode (CPE) modified with graphene quantum dots (GQD), 2-chlorobenzoyl ferrocene (2CBF) and ionic liquid (IL). Then, the electrochemical behavior of levodopa alone and simultaneously with cabergoline at the surface of GQDs/2CBF/IL/CPE was investigated in phosphate buffer solution (PBS). Under optimal PBS, pH=7 condition, oxidation peak current has been found proportional to levodopa concentration in the range between 0.07 μM and 500.0 μM, with the limit of detection (LOD) of 0.02 μM (S/N=3). Outputs showed that at GQDs/2CBF/IL/CPE surface, the levodopa and cabergoline oxidation peaks are separated by the potential difference of 200 mV. In addition, it was found that this modified electrode possesses acceptable sensitivity, selectivity, stability and repeatability. All these properties were sufficient to allow simultaneous detection of levodopa and cabergoline in real samples at the surface of GQDs/2CBF/IL/CPE. This was supported by the successful application of this electro­chemical sensor electrode for the determination of levodopa and cabergoline in urine, serum, and cabergoline tablets.

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