Improvement of electrocatalytic effect in voltammetric sensors based on phthalocyanines

Voltammetric sensors based on phthalocyanines have been used to detect a variety of compounds. In this paper, the state of the art of sensors prepared using classical techniques will be revised. Then, new strategies to improve the performance of the sensors will be described using as example sensors chemically modified with lutetium bisphthalocyanine (LuPc[Formula: see text] dedicated to the detection of phenols of interest in the food industry. Classical LuPc2 carbon paste electrodes can detect phenols such as catechol, caffeic acid or pyrogallol with limits of detection in the range of 10[Formula: see text]–10[Formula: see text] M. The performance can be improved by using nanostructured Langmuir–Blodgett (LB) or Layer by Layer (LbL) films. The enhanced surface to volume ratio produce an increase in the sensitivity of the sensors. Limits of detection of 10[Formula: see text]–10[Formula: see text] M are attained, which are one order of magnitude lower than those obtained using conventional carbon paste electrodes. Moreover, these techniques can be used to co-immobilize two electrocatalytic materials in the same device. The limits of detection obtained in LB sensors combining LuPc2/AuNPs or LuPc2/CNT are further improved. Finally, the LB technique has been used to prepare biosensors where a phenol oxydase (such as tyrosinase or lacasse) is immobilized in a biomimetic environment that preserves the enzymatic activity. Moreover, LuPc2 can be co-immobilized with the enzyme in a lipidic film formed by arachidic acid (AA). LuPc2 can act as an electron mediator facilitating the electron transfer. These biomimetic sensors formed by LuPc2/AA/enzyme show Limits of detection of 10[Formula: see text] M and an enhanced selectivity.

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Multisensor systems based on phthalocyanines for monitoring the quality of grapes

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424616500796 ◽

2016 ◽

Vol 20 (08n11) ◽

pp. 889-894 ◽

Cited By ~ 5

Author(s):

Maria Luz Rodriguez-Mendez ◽

Celia García-Hernandez ◽

Cristina Medina-Plaza ◽

Cristina García-Cabezón ◽

Jose Antonio de Saja

Keyword(s):

State Of The Art ◽

Layer By Layer ◽

Carbon Paste ◽

Electron Mediator ◽

Multisensor Systems ◽

Langmuir Blodgett ◽

Different Types ◽

Production Stages ◽

Nanostructured Sensors

Arrays of phthalocyanine-based sensors with complementary activity have been used to develop voltammetric electronic tongues. Such systems have demonstrated to be useful in enology for the evaluation of quality of wines in different production stages, from grapes to bottles. In this paper, the state of the art of multisensor systems based on phthalocyanines dedicated to the analysis of musts (juices obtained from crushed grapes) is described. Such multisensor systems cover different types of sensors from simple Carbon Paste Electrodes, to sophiticated nanostructured sensors, including Langmuir–Blodgett or Layer by Layer thin films and biomimetic biosensors where phthalocyanines play a crucial role as electron mediator between enzymes and electrodes. In all cases, multisensor systems based on phthalocyanines have been able to discriminate musts prepared from different varieties of grapes. The performance of these systems can be improved by combining non-specific sensors with biosensors containing enzymes selective to phenols. In this case, excellent relationships have been found between the responses provided by the array and the content in phenols and acids provided by traditional chemical analysis.

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Electronic tongue formed by sensors and biosensors containing phthalocyanines as electron mediators: Application to the analysis of red grapes

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424613501137 ◽

2014 ◽

Vol 18 (01n02) ◽

pp. 76-86 ◽

Cited By ~ 18

Author(s):

Cristina Medina-Plaza ◽

Gema Revilla ◽

Raquel Muñoz ◽

José Antonio Fernández-Escudero ◽

Enrique Barajas ◽

...

Keyword(s):

Glucose Oxidase ◽

Electronic Tongue ◽

Principal Component ◽

Carbon Paste ◽

Electron Mediator ◽

Enzyme Substrate ◽

Voltammetric Sensors ◽

The Individual ◽

Electron Mediators

An electronic tongue formed by voltammetric sensors and biosensors containing phthalocyanines has been developed and used to analyze grapes of different varieties. The sensors are prepared using the carbon paste technique and have been chemically modified with different metallophthalocyanines. In turn, biosensors consist of carbon paste electrodes modified with phthalocyanines combined with tyrosinase or glucose oxidase. The response of the individual sensors towards model solutions of glucose and catechol have demonstrated that the voltammetric responses depend on the nature of the phthalocyanine, evidencing the important role of the electron mediator in the performance of the sensors. The capability of the system to discriminate grapes according to their sugar and their polyphenolic content has been evidenced using Principal Component Analysis. It has been demonstrated that the proposed array of sensors combines the advantages of classical phthalocyanine based sensors — that provide global information about the sample —, with the specificity of the enzyme substrate reaction typical of biosensors. For this reason, the selectivity of the multisensor system and its capability of discrimination is clearly improved when biosensors containing glucose oxidase or tyrosinase are included in the array.

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Phenylenediamine-containing chemically modified carbon paste electrodes as catalytic voltammetric sensors

Analytical Chemistry ◽

10.1021/ac00260a032 ◽

1983 ◽

Vol 55 (9) ◽

pp. 1586-1591 ◽

Cited By ~ 55

Author(s):

K. Ravichandran ◽

Richard P. Baldwin

Keyword(s):

Carbon Paste ◽

Chemically Modified ◽

Carbon Paste Electrodes ◽

Voltammetric Sensors ◽

Modified Carbon Paste Electrodes

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Carbon paste electrodes modified with SnO2/CuS, SnO2/SnS and Cu@SnO2/SnS nanocomposites as voltammetric sensors for paracetamol and hydroquinone

Microchimica Acta ◽

10.1007/s00604-018-2948-6 ◽

2018 ◽

Vol 185 (9) ◽

Cited By ~ 7

Author(s):

Ebrahim Naghian ◽

Mostafa Najafi

Keyword(s):

Carbon Paste ◽

Carbon Paste Electrodes ◽

Voltammetric Sensors

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Silver Nanowires as Electron Transfer Mediators in Electrochemical Catechol Biosensors

Sensors ◽

10.3390/s21030899 ◽

2021 ◽

Vol 21 (3) ◽

pp. 899

Author(s):

Coral Salvo-Comino ◽

Fernando Martin-Pedrosa ◽

Cristina Garcia-Cabezon ◽

Maria Luz Rodriguez-Mendez

Keyword(s):

Electron Transfer ◽

Limit Of Detection ◽

Silver Nanowires ◽

High Surface ◽

Volume Ratio ◽

Homogeneous Distribution ◽

Electron Mediator ◽

Force Microscopy ◽

Voltammetric Detection ◽

Order Of Magnitude

The integration of nanomaterials as electron mediators in electrochemical biosensors is taking on an essential role. Due to their high surface-to-volume ratio and high conductivity, metallic nanowires are an interesting option. In this paper, silver nanowires (AgNWs) were exploited to design a novel catechol electrochemical biosensor, and the benefits of increasing the aspect ratio of the electron mediator (nanowires vs. nanoparticles) were analyzed. Atomic force microscopy (AFM) studies have shown a homogeneous distribution of the enzyme along the silver nanowires, maximizing the contact surface. The large contact area promotes electron transfer between the enzyme and the electrode surface, resulting in a Limit of Detection (LOD) of 2.7 × 10−6 M for tyrosinase immobilized onto AgNWs (AgNWs-Tyr), which is one order of magnitude lower than the LOD of 3.2 × 10−5 M) obtained using tyrosinase immobilized onto silver nanoparticles (AgNPs-Tyr). The calculated KM constant was 122 mM. The simultaneous use of electrochemistry and AFM has demonstrated a limited electrochemical fouling that facilitates stable and reproducible detection. Finally, the biosensor showed excellent anti-interference characteristics toward the main phenols present in wines including vanillin, pyrogallol, quercetin and catechin. The biosensor was able to successfully detect the presence of catechol in real wine samples. These results make AgNWs promising elements in nanowired biosensors for the sensitive, stable and rapid voltammetric detection of phenols in real applications.

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Influence of Nitrogen-Doped Carbon Dot and Silver Nanoparticle Modified Carbon Paste Electrodes on the Potentiometric Determination of Tobramycin Sulfate: A Comparative Study

Chemosensors ◽

10.3390/chemosensors9030052 ◽

2021 ◽

Vol 9 (3) ◽

pp. 52

Author(s):

Nermine V. Fares ◽

Passant M. Medhat ◽

Christine M. El Maraghy ◽

Sherif Okeil ◽

Miriam F. Ayad

Keyword(s):

Silver Nanoparticle ◽

Carbon Nanodots ◽

Carbon Paste ◽

X Ray Diffraction ◽

Loteprednol Etabonate ◽

Carbon Paste Electrodes ◽

Transmission Electron ◽

Nernstian Slope ◽

Nitrogen Doped Carbon ◽

Modified Carbon Paste Electrodes

Two inexpensive and simple methods for synthesis of carbon nanodots were applied and compared to each other, namely a hydrothermal and microwave-assisted method. The synthesized carbon nanodots were characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis), photoluminescence (PL), Fourier transform-infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The synthesized microwave carbon nanodots had smaller particle size and were thus chosen for better electrochemical performance. Therefore, they were used for our modification process. The proposed electrodes performance characteristics were evaluated according to the IUPAC guidelines, showing linear response in the concentration range 10−6–10−2, 10−7–10−2, and 10−8–10−2 M of tobramycin with a Nernstian slope of 52.60, 58.34, and 57.32 mV/decade for the bare, silver nanoparticle and carbon nanodots modified carbon paste electrodes, respectively. This developed potentiometric method was used for quantification of tobramycin in its co-formulated dosage form and spiked human plasma with good recovery percentages and without interference of the co-formulated drug loteprednol etabonate and excipients.

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Polyvinyl Chloride Modified Carbon Paste Electrodes for Sensitive Determination of Levofloxacin Drug in Serum, Urine, and Pharmaceutical Formulations

Sensors ◽

10.3390/s21093150 ◽

2021 ◽

Vol 21 (9) ◽

pp. 3150

Author(s):

Fatehy M. Abdel-Haleem ◽

Sonia Mahmoud ◽

Nour Eldin T. Abdel-Ghani ◽

Rasha Mohamed El Nashar ◽

Mikhael Bechelany ◽

...

Keyword(s):

Bacterial Infections ◽

Pharmaceutical Preparation ◽

Pharmaceutical Formulations ◽

Selectivity Coefficient ◽

Pvc Membrane ◽

Carbon Paste ◽

Serum Samples ◽

Carbon Paste Electrodes ◽

Antibiotic Drug

Levofloxacin (LF) is a medically important antibiotic drug that is used to treat a variety of bacterial infections. In this study, three highly sensitive and selective carbon paste electrodes (CPEs) were fabricated for potentiometric determination of the LF drug: (i) CPEs filled with carbon paste (referred to as CPE); (ii) CPE coated (drop-casted) with ion-selective PVC membrane (referred to as C-CPE); (iii) CPE filled with carbon paste modified with a plasticizer (PVC/cyclohexanone) (referenced as P-CPE). The CPE was formulated from graphite (Gr, 44.0%) and reduced graphene oxide (rGO, 3.0%) as the carbon source, tricresyl phosphate (TCP, 47.0%) as the plasticizer; sodium tetrakis[3,5-bis(trifluoromethyl)phenyl] borate (St-TFPMB, 1.0%) as the ion exchanger; and levofloxacinium-tetraphenylborate (LF-TPB, 5.0%) as the lipophilic ion pair. It showed a sub-Nernstian slope of 49.3 mV decade−1 within the LF concentration range 1.0 × 10−2 M to 1.0 × 10−5 M, with a detection limit of 1.0 × 10−5 M. The PVC coated electrode (C-CPE) showed improved sensitivity (in terms of slope, equal to 50.2 mV decade−1) compared to CPEs. After the incorporation of PVC paste on the modified CPE (P-CPE), the sensitivity increased at 53.5 mV decade−1, indicating such improvement. The selectivity coefficient (log KLF2+,Fe+3pot.) against different interfering species (Na+, K+, NH4+, Ca2+, Al3+, Fe3+, Glycine, Glucose, Maltose, Lactose) were significantly improved by one to three orders of magnitudes in the case of C-CPE and P-CPE, compared to CPEs. The modification with the PVC membrane coating significantly improved the response time and solubility of the LF-TPB within the electrode matrix and increased the lifetime. The constructed sensors were successfully applied for LF determination in pharmaceutical preparation (Levoxin® 500 mg), spiked urine, and serum samples with high accuracy and precision.

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