Electrochemical Monitoring of DNA Hybridization by Multiwalled Carbon Nanotube Based Screen Printed Electrodes

The application of multiwalled carbon nanotube (MWCNT) based screen printed graphite electrodes (SPEs) was explored in this study for the electrochemical monitoring of DNA hybridization related to specific sequences on Hepatitis B virus (HBV) DNA. After the microscopic characterization of bare MWCNT‐SPEs and DNA immobilized ones was performed, the optimization of assay has been studied. The development of screen printing process combined with nanomaterial based disposable sensor technology leads herein a great opportunity for DNA detection using differential pulse voltammetry (DPV) by measuring the guanine oxidation signal observed at +1.00 V in the presence of DNA hybridization between HBV probe and its complementary, target. The detection limit estimated for signal to noise ratios =3 corresponds to 96.33 nM target concentration in the 40 μL samples. The advantages of carbon nanotube based screen printed electrode used for electrochemical monitoring of DNA hybridization are discussed with sensitivity, selectivity and reproducibility in comparison with previous nanomaterial based electrochemical transducers developed for DNA or other biomolecular recognitions.     

Screen-printed electrochemical sensors for label-free potentiometric and impedimetric detection of human serum albumin

Herein, two electrochemical methods based on potentiometric and impedimetric transductions were presented for albumin targeting, employing screen-printed platforms (SPEs) to make easy and cost-effective sensors with good detection merits. The SPEs incorporated ion-to-electron multi-walled carbon nanotubes (MWCNTs) transducer. Sensors were constructed using either tridodecyl methyl-ammonium chloride (TDMACl) (sensor I) or aliquate 336S (sensor II) in plasticized polymeric matrices of carboxylated poly (vinyl chloride) (PVC-COOH). Analytical performances of the sensors were evaluated using the above-mentioned electrochemical techniques. For potentiometric assay, constructed sensors responded to albumin with −81.7 ± 1.7 (r² = 0.9986) and −146.2 ± 2.3 mV/decade (r² = 0.9991) slopes over the linearity range 1.5 μM–1.5 mM with 0.8 and 1.0 μM detection limits for respective TDMAC- and aliquate-based sensors. Interference study showed apparent selectivity for both sensors. Impedimetric assays were performed at pH = 7.5 in 10 mM PBS buffer solution with a 0.02 M [Fe(CN)₆]^−3/−4 redox-active electrolyte. Sensors achieved detection limits of 4.3 × 10⁻⁸ and 1.8 × 10⁻⁷ M over the linear ranges of 5.2×10⁻⁸–1.0×10⁻⁴ M and 1.4×10⁻⁶–1.4×10⁻³ M, with 0.09 ± 0.004 and 0.168 ± 0.009 log Ω/decade slopes for sensors based on TDMAC and aliquate, respectively. These sensors are characterized with simple construction, high sensitivity and selectivity, fast response time, single-use, and cost-effectiveness. The methods were successfully applied to albumin assessment in different biological fluids.     

Carbon Nanodots as Electrocatalysts towards the Oxygen Reduction Reaction

Electrocatalysts perform a key role in increasing efficiency of the oxygen reduction reaction (ORR) and as a result, efforts have been made by the scientific community to develop novel and cheap materials that have the capability to exhibit low ORR overpotentials and allow the reaction to occur via a 4 electron pathway, thereby mimicking as close as possible to traditionally utilised platinum. In that context, two different types of carbon nanodots (CNDs) with amide (CND‐CONH₂) and carboxylic (CND‐COOH) surface groups, have herein been fabricated and shown to exhibit excellent electrocatalytic activity towards the ORR in acid and basic media (0.1 M H₂SO₄ and 0.1 M KOH). CND surface modified carbon screen‐printed electrodes allow for a facile electrode modification and enabling the study of the CNDs electrocatalytic activity towards the ORR. CND‐COOH modified SPEs are found to exhibit improved ORR peak current and reduced overpotential by 21.9 % and 26.3 %, respectively compared to bare/unmodified SPEs. Additionally, 424 μg cm⁻² CND‐COOH modified SPEs in oxygenated 0.1 M KOH are found to facilitate the ORR via a near optimal 4 (3.8) electron ORR pathway. The CNDs also exhibited excellent long‐term stability and tolerance with no degradation being observed in the achievable current with the ORR current returning to the baseline level within 100 seconds of exposure to a 1.5 M solution of methanol. In summary, the CND‐COOH could be utilised as a cathodic electrode for PEMFCs offering greater stability than a commercial Pt electrode.     

Lead Sensor Using Gold Nanostructured Screen‐Printed Carbon Electrodes as Transducers

Gold nanostructured screen‐printed carbon electrodes are demonstrated to be suitable transducers for the determination of lead using square‐wave voltammetry. Reproducible gold nanostructures have been obtained by direct electrochemical deposition. A calibration plot from 2.5 to 250 μg/L was obtained in acidic solutions of Pb(II) with a reproducibility of 4% (n=10). The detection limit was 0.09 μg/L of lead. The method is then applied to perform a blood lead analysis by adjusting square‐wave parameters in capillary or venous blood with a minimum sample pretreatment and excellent accuracy and reproducibility.     

Selective Electroanalysis of Ascorbic Acid Using a Nickel Hexacyanoferrate and Poly(3,4‐ethylenedioxythiophene) Hybrid Film Modified Electrode

The mixed‐valent nickel hexacyanoferrate (NiHCF) and poly(3,4‐ethylenedioxythiophene) (PEDOT) hybrid film (NiHCF‐PEDOT) was prepared on a glassy carbon electrode (GCE) by multiple scan cyclic voltammetry. The films were characterized using atomic force microscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, X‐ray diffraction, and electrochemical impedance spectroscopy (AC impedance). The advantages of these films were demonstrated for the detection of ascorbic acid (AA) using cyclic voltammetry and amperometric techniques. The electrocatalytic oxidation of AA at different electrode surfaces, such as the bare GCE, the NiHCF/GCE, and the NiHCF‐PEDOT/GCE modified electrodes, was determined in phosphate buffer solution (pH 7). The AA electrochemical sensor exhibited a linear response from 5×10⁻⁶ to 1.5×10⁻⁴ M (R²=0.9973) and from 1.55×10⁻⁴ to 3×10⁻⁴ M (R²=0.9983), detection limit=1×10⁻⁶ M, with a fast response time (3 s) for AA determination. In addition, the NiHCF‐PEDOT/GCE was advantageous in terms of its simple preparation, specificity, stability and reproducibility.     

Flow Injection Analysis of Maleic Hydrazide Using an Electrochemical Sensor Based on Palladium‐Dispersed Carbon Paste Electrode

A new analytical methodology for the electrochemical detection of the herbicide maleic hydrazide (3,6‐dihydroxypyridazine) by flow injection analysis is presented. This method is supported by the novel application of a palladium‐dispersed carbon paste electrode as an amperometric sensor for this herbicide. Maleic hydrazide shows anodic electrochemical activity on carbon‐based electrodes (glassy carbon or carbon paste electrodes) in all the pH range. This electrochemical activity is enhanced using metal‐dispersed carbon paste electrodes, especially at Pd‐dispersed CPE which displays good oxidation signals at 690 mV (0.050 M phosphate buffer pH 7.0), 140 mV lower than at unmodified electrodes. Under the optimized conditions, the electroanalytical performance of Pd‐dispersed CPE in flow injection analysis was excellent, with good reproducibility (RSD 3.3%) and a wide linear range (1.9×10^?7 to 1.0×10^?4 mol L^?1). A detection limit of 1.4×10^?8 mol L^?1 (0.14 ng maleic hydrazide) was obtained for a sample loop of 100 μL at a fixed potential of 700 mV in 0.050 M phosphate buffer solution at pH 7.0 and a flow rate of 2.0 mL min^?1. The proposed method was applied for the maleic hydrazide detection in natural drinking water samples.     

η1‐Allypalladium Complexes with Tridentate PNP’ Ligand for the Assembly of Modified Screen Printed Electrodes: an Electrochemical Study

Specific Pd‐based organometallic complex, in particular the [Pd(η¹‐CH₂? CH=CH₂)(P? N? P’)]BF₄ was used for the assembly of chemically modified Screen Printed Electrodes (SPEs) and their electrochemical reactivity was also investigated. For this purpose potassium ferricyanide, hexaammineruthenium(III) chloride, sodium hexachloroiridate‐(III) hydrate, ascorbic acid (AA), uric acid (UA), acetaminophen (Ac), guanine (G) and adenine (A) were used to study the electron‐transfer processes, which occurred at modified SPEs, fabricated by using the [Pd(η¹‐CH₂? CH=CH₂)(P? N? P’)]BF₄, applying the drop casting procedure. Interesting results were obtained in the case of the guanine (G) quantitative detection, especially in terms of a wide range of concentration (2.5–40 nM), an high sensitivity (of 49.0 A M^?1 cm^?2), a low detection limit (LOD=1.0 nM) and a fast response time (of t=2 s). The intra‐electrode reproducibility (RSD%) was <1 % for the same SPE used for each point of the calibration plot. The inter‐electrode reproducibility (RSD%), estimated by using different SPEs for each single point of the quantitative calibration graph, ranging from 5 to 10 %, better than that exhibited by other different chemical sensors, described in literature, and reported in this work for comparison. In addition, the high selectivity of the chemically modified sensors toward the oxidation of guanine, exhibited in presence of a mixture of G+A, in the same electrochemical bath solution, could be related to the different electro‐catalytic mechanisms, as demonstrated by the XPS study. This chemical sensor prototype could be very promising for bio‐medicine applications.     

Electrochemical Analysis of Acrylamide Using Screen‐Printed Carboxylated Single‐Walled Carbon Nanotube Electrodes

Acrylamide (AA) was electrochemically detected and quantified by means of its voltammetric response on carboxylic modified Single‐Walled Carbon Nanotube Screen Printed Electrodes (COOH‐SWCNT‐SPEs). The electroreduction signal of AA was proportional to AA concentration at low values (below 300 µM) and the observed sensitivity was explained in terms of AA adsorption on the COOH‐SWCNT‐SPEs that was demonstrated using the electrochemical response of [Fe(CN)₆]^3? and [Fe(CN)₆]^4? and Raman spectroscopy experiments. In order to test the suggested analytic approach (LOD of 0.03 µM, LOQ of 0.04 µM), detection and quantification of AA in fried potatoes was carried out using the proposed electrochemical method and HPLC. Both techniques showed similar contents of AA.     

Carbon‐nanotube Modified Screen‐printed Electrode for the Simultaneous Determination of Nitrite and Uric Acid in Biological Fluids Using Batch‐injection Amperometric Detection

A portable electroanalytical system applied for rapid and simultaneous determination of uric acid (UA) and nitrite (NIT) in human biological fluids (urine, saliva and blood) is reported. The system is based on batch‐injection analysis with multiple‐pulse amperometric (BIA‐MPA) detection using screen‐printed electrodes (SPEs) modified with multi‐walled carbon nanotubes. Sample dilution in optimized electrolyte (0.1 mol L⁻¹ Britton‐Robinson buffer pH 2) followed by injection of 100 μL on the electrode surface using an electronic micropipette is performed. UA is detected at +0.45 V and both UA+NIT at +0.70 V. Linear calibration plots for UA and NIT were obtained over the range of 1–500 μmol L⁻¹ with detection limits of 0.05 and 0.06 μmol L⁻¹, respectively. For comparison, a differential‐pulse voltammetric (DPV) method was optimized, and linear calibration plots for UA and NIT were obtained over range of 1–30 μmol L⁻¹ and 1–40 μmol L⁻¹ with detection limits of 0.1 and 0.3 μmol L⁻¹, respectively. BIA‐MPA is highly precise (RSD<1.3 %), fast (160 h⁻¹) and free from sample‐matrix interferences as recovery values ranged from 77 to 121 % for spiked samples (short contact time of sample aliquot with SPE). Contrarily, recovery tests conducted using DPV did not provide adequate recovery values (>150 %), probably due to the longer contact time of the SPE with the biological samples during analysis leading to a severe interference of sample matrices.     

A Novel Enzymatic Glucose Biosensor and Nonenzymatic Hydrogen Peroxide Sensor Based on (3‐Aminopropyl) Triethoxysilane Functionalized Reduced Graphene Oxide

In the present study, a novel enzymatic glucose biosensor using glucose oxidase (GOx) immobilized into (3‐aminopropyl) triethoxysilane (APTES) functionalized reduced graphene oxide (rGO‐APTES) and hydrogen peroxide sensor based on rGO‐APTES modified glassy carbon (GC) electrode were fabricated. Nafion (Nf) was used as a protective membrane. For the characterization of the composites, Fourier transform infrared spectroscopy (FTIR), X‐ray powder diffractometer (XRD), and transmission electron microscopy (TEM) were used. The electrochemical properties of the modified electrodes were investigated using electrochemical impedance spectroscopy, cyclic voltammetry, and amperometry. The resulting Nf/rGO‐APTES/GOx/GC and Nf/rGO‐APTES/GC composites showed good electrocatalytical activity toward glucose and H₂O₂, respectively. The Nf/rGO‐APTES/GC electrode exhibited a linear range of H₂O₂ concentration from 0.05 to 15.25 mM with a detection limit (LOD) of 0.017 mM and sensitivity of 124.87 μA mM⁻¹ cm⁻². The Nf/rGO‐APTES/GOx/GC electrode showed a linear range of glucose from 0.02 to 4.340 mM with a LOD of 9 μM and sensitivity of 75.26 μA mM⁻¹ cm⁻². Also, the sensor and biosensor had notable selectivity, repeatability, reproducibility, and storage stability.     

Comparison of Insulin Determination on NiNPs/chitosan‐ MWCNTs and NiONPs/chitosan‐MWCNTs Modified Pencil Graphite Electrode

The rising amount of patients suffering for diabetes mellitus increases the requirements for effective insulin sensors. Carbon materials are a suitable choice for the development of insulin sensors due to their electrochemical characteristics. Pencil graphite electrodes (PGE) represent the trade‐off between price and excellent conductive properties. The modification of PGE by NiO and Ni nanoparticles fixed by chitosan results in surface area enlargement and improved electrocatalytic properties. This paper is focused on the comparison of different properties of Ni and NiO nanoparticles and their effect on redox reaction mechanism of insulin and detection characteristics. The electrode modified by Ni nanoparticles displays linear range of 1 μM–5 μM (R² 0.80), limit of detection (LOD) of 4.34 μM and sensitivity of 0.12 μA/μM. On the other hand, the electrode modified by NiO nanoparticles displays enhanced electrochemical characteristics such as linear range of 0.05 μM–5 μM (R² 0.99), limit of detection of 260 nM and sensitivity of 0.64 μA/μM. These properties make the NiO nanoparticles modified PGE the appropriate candidate for insulin determination.     

Electrochemical Detection of Para‐nitrophenol using Copper Metal Nanoparticles Modified Gold Electrode

para‐Nitrophenol (p‐NP) is a high priority environmental pollutant. For the sake of safety, sensitive detection of its presence in water resources and food is highly important. The present article describes the use of copper metal nanoparticles for selective and sensitive electrochemical detection of p‐NP in pure and real sample. For this the gold electrode was fabricated by polyvenylpyrrolidone stabilized copper metal nanoparticles (ca . 4 nm d.) via self‐assembled 4,4′‐bipyridine monolayer and characterized by microscopic and electrochemical techniques. The newly developed sensor permits for sensitive detection of p‐NP in a linear concentration range of 1–500 μM with lowest detection limit of 0.34 nM and high sensitivities 247.1 μA cm⁻² μM⁻¹. The sensor electrode exhibited high stability, reproducibility, good selectivity in the presence of potential interfering agents and had an excellent capability for the selective determination of p‐NP in river water without preliminary treatments.     

Isatin Analysis Using Flow Injection Analysis with Amperometric Detection – Comparison of Tetrahedral Amorphous Carbon and Diamond Electrode Performance

Isatin is an endogenous indole compound in humans and rodents that has a wide range of biological activity. In rat models, isatin concentrations have been shown to increase in the heart, brain, blood plasma, and urine with stress. Studies on patients suffering from Parkinson's disease have indicated a correlation between progress of the disease and urinary output of the molecule. Isatin is electrochemically active and can therefore be detected with electrochemical techniques. In this work, we compared the performance of a nitrogen‐incorporated tetrahedral amorphous carbon (ta‐C:N) and a boron‐doped nanocrystalline diamond thin‐film electrode for the oxidative detection of this biomolecule using flow injection analysis with amperometric detection. The measurements were performed in 0.1 phosphate buffer pH 7.2. The ta‐C:N electrode, like boron‐doped nanocrystalline diamond, exhibits some excellent properties for electroanalytical measurements including (i) low background current and noise, (ii) microstructural stability at positive detection potentials, and (iii) good activity for a wide range of bioanalytes without conventional surface pretreatment. The results reveal that both electrodes exhibit a linear dynamic range from 100 to 0.1 μmol L⁻¹, a short‐term response variability 3–4 % RSD (30 injections), a sensitivity of 18 mA M^‐1, and a limit of detection (S/N=3) of 1.0×10⁻⁷ mol L⁻¹ (14 ng mL⁻¹ or 2.5 fmol).     

Voltammetry of Benzo[a]pyrene in Aqueous and Nonaqueous Media: Adsorptive Stripping Voltammetric Determination at Pencil Graphite Electrode

A detailed study of the electrochemical oxidation of Benzo[a]pyrene (BaP) at the glassy carbon and pencil graphite electrodes was carried out in aqueous and nonaqueous media. Using square‐wave stripping mode, the compound yielded a well‐defined voltammetric response at pencil graphite electrode in acetate buffer, pH 4.8 at +1.13 V (vs. Ag/AgCl) (a preconcentration step being carried out at a fixed potential of +0.70 V for 180 s). The process could be used to determine BaP concentrations in the range 0.25–1.25 μM, with a detection limit of 0.027 μM (6.82 μg L^?1). The applicability to assay of spiked human urine samples was also illustrated.     

Nanoporous Gold Microelectrode: A Novel Sensing Platform for Highly Sensitive and Selective Determination of Arsenic (III) using Anodic Stripping Voltammetry

A home‐made gold microelectrode (Au‐μE) was fabricated and its surface was modified with nanoporous gold structures via a facile electrochemical approach (anodization followed by electrochemical reduction method). The fabricated nanoporous Au microelectrode (NPG‐μE) was used as a sensor probe for the determination of As(III) in 1.0 mol L⁻¹ HCl solution using square wave anodic stripping voltammetry (SWASV) technique. Field emission scanning electron microscopy (FE‐SEM) and cyclic voltammetry were used to characterize the surface morphology and assess the electrochemical surface area and the roughness factor of the NPG‐μE. SWASVs recorded with the NPG‐μE in As(III) solutions indicated linear behaviour in the concentration ranges of 10–200 μg L⁻¹ and 2–30 μg L⁻¹, with regression coefficients of 0.996 and 0.999 at a deposition time of 120 s, respectively. The limit of detection (LOD) was found to be 0.62 μg L⁻¹ with high sensitivity of 29.75 μA (μg L⁻¹)⁻¹ cm⁻². Repeatability and reproducibility were also examined and values were determined as 3.2 % and 9.0 %. Negligible interference from major interfering copper ion was noticed, revealing the excellent anti‐interference property of the proposed sensing platform. The developed NPG‐μE was successfully used for As(III) determination in tap water samples.     

Electrochemical Detection of Vascular Endothelial Growth Factor by Molecularly Imprinted Polymer

In this study, we report the development of a sensitive label‐free impedimetric sensor based on molecularly imprinted polymer (MIP) as biomimetic receptor coupled with screen‐printed electrodes (SPEs) for the detection of vascular endothelial growth factor (VEGF). Firstly, electropolymerization of o‐phenylenediamine (o‐PD) in the presence of VEGF molecule by cyclic voltammetry was performed onto graphite screen‐printed electrodes. The solvent extraction of the target was then carried out. The MIP based sensor was characterized by electrochemical techniques and scanning electron microscopy (SEM). Using optimized experimental conditions, the single‐use MIP‐based sensor showed a good analytical performance for VEGF detection from 20 to 200 pg mL^?1 with limit of detection of 0.08 pg mL^?1. Finally, the developed MIP‐based sensor in human serum samples was also tested.     

Improvement of analytical performances of a disposable electrochemical immunosensor by using magnetic beads

A comparison of two electrochemical immunosensing strategies for PCBs detection, based on the use of two different solid phases, is here discussed. In both cases, carbon-based screen-printed electrodes (SPEs) are used as transducers in a direct competitive immunoassay scheme, where PCBs in solution compete with the tracer PCB28-alkaline phosphatase (AP) labeled for antibodies immobilized onto the solid-phase.In the standard format (called EI strategy), SPEs are both the solid-phase for immunoassay and electrochemical transducers: in this case the immunochemical reaction occurs onto the working electrode. Finally, the enzymatic substrate is added and an electroactive product is generated and detected by electrochemical measurement. In order to improve the performances of the system, a new approach (called EMI strategy) is developed by using functionalized magnetic beads as solid phase for the competitive assay; only after the immunosensing step they are captured by a magnet onto the working surface of the SPE for the electrochemical detection.Experimental results evidenced that the configuration based on the use of separate surfaces for immunoassay and for electrochemical detection gave the best results in terms of sensitivity and speed of the analysis. The improvement of analytical performances of the immunosensor based on EMI strategy was also demonstrated by the analysis of some spiked samples.     

Rational Design of Highly Efficient One-pot Synthesis of Ternary PtNiCo/FTO Nanocatalyst for Hydroquinone and Catechol Sensing

In this work, we present a simple and efficient method for preparation of widely dispersed PtNiCo nanocatalyst on FTO without the use of any heavy complex structure. The proposed nanocatalyst enhances the chemical interaction of PtNiCo/FTO and increases its catalytic activity, which was used for electrochemical sensing of catechol and hydroquinone. The surface morphology was characterized by TEM, HRTEM, and XRD. The size of the PtNiCo/FTO octahedrons nanocatalyst was about 0.35–4 nm. Gradual increase of concentration exhibited linearity in oxidation peak response up to 1100 μM with a low detection limit of 0.79 μM for HQ and 1.05 μM for CC. The sensitivity is 1035 μAmM⁻¹ cm⁻² for catechol and 1197 μAmM⁻¹ cm⁻² for hydroquinone. The prepared nanomaterial/sensor applied to real water samples with good reproducibility (98–99 %).     

Electrode Modification through Click Chemistry Using Ni and Co Alkyne Phthalocyanines for Electrocatalytic Detection of Hydrazine

This work reports on the development of sensors for the detection of hydrazine using glassy carbon electrodes (GCE) modified with phthalocyanines through click chemistry. Tetrakis(5‐hexyn‐oxy) cobalt(II) phthalocyanine (complex 2 ) and tetrakis(5‐hexyn‐oxy) nickel(II) phthalocyanine (complex 3 ) were employed as electrode modifiers for hydrazine detection. The GCE was first grafted via the in situ diazotization of a diazonium salt, rendering the GCE surface layered with azide groups. From this point, the 1, 3‐dipolar cycloaddition reaction, catalysed by a copper catalyst was utilised to “click” the phthalocyanines to the surface of the grafted GCE. The modified electrodes were characterized by scanning electrochemical microscopy, X‐ray photoelectron spectroscopy and cyclic voltammetry. The electrografted CoP 2 ‐clicked‐GCE and NiP 3 ‐clicked‐GCE exhibited electrocatalytic activity towards the detection of hydrazine. The limit of detection (LoD) for the CoPc‐GCE was 6.09 μM, while the NiPc‐GCE had a LoD of 8.69 μM. The sensitivity was 51.32 μA mM⁻¹ for the CoPc‐GCE and 111.2 μA mM⁻¹ for the NiPc‐GCE.     

Electropolymerization of Metallophthalocyanines Carrying Redox Active Metal Centers and their Electrochemical Pesticide Sensing Application

In this study, modified electrodes were constructed with the electropolymerization of metallophthalocyanines (MPcs) carrying redox active metal cations and electropolymerizable substituents. Then these electrodes were tested as selective and sensitive electrochemical pesticide sensors. Incorporation of the redox active Co(II) (CoPc(MOR‐NAF)), Cl–Mn(III) (MnPc(MOR‐NAF)), and Ti(IV)O (TiOPc(MOR‐NAF)) metal cations into Pc cavity increased the redox activity of Pc ring. Moreover, redox active and electropolymerizable 5‐{[(1E)‐(4‐morpholin‐4‐ylphenyl)methylene]amino}‐1‐naphthoxy substituents (MOR‐NAF) on the Pc ring triggered coating of the complexes on the electrode surface with the electropolymerization reactions. Therefore, modified electrodes GCE/MPc(MOR‐NAF) were constructed with the electropolymerizations of MPcs. These electrodes illustrated reasonable redox activity and conductivity for the potential applications in different fields of the electrochemical technologies. Pesticide sensing measurements indicated that changing the metal center of the complexes significantly altered their sensing activities. Among the complexes, GCE/CoPc(MOR‐NAF) electrode behaved as the most sensitive and selective electrode and it sensed the parathion with good selectivity and sensitivity. GCE/CoPc(MOR‐NAF) electrode showed a wider linear range (0.075‐5.75 μmoldm⁻³) and smaller LOD (0.025 μmoldm⁻³) and higher sensitivity (3.46 Acm⁻²M⁻¹) for the parathion sensing. Although GCE/TiOPc(MOR‐NAF) electrode also sensed the parathion with a high sensitivity, its selectivity was poor and the linear range of this sensing was very narrow. Differently GCE/Cl–MnPc(MOR‐NAF) electrode only sensed eserine with reasonably sensitivity.