Screen-printed Working Electrode Research Articles

New methodological approach for deep penetrating geochemistry and environmental studies, Part 2: field determination of Co(II)/Ni(II) and Pb(II)/Zn(II) of on-site soil extractions by electrochemical stripping techniques

In the framework of deep penetrating geochemistry for mineral exploration, we report a field electroanalytical method using disposable screen-printed working electrodes able to quantify metal pathfinders in partial extracts of soil samples at the nanomolar level on-site. Four metal pathfinders (Co, Ni, Pb and Zn) were chosen due to their geological interest and suitability of electrochemical detection. Square-wave anodic stripping voltammetry (SW-ASV) was developed for the simultaneous detection of Pb(II) and Zn(II) providing limits of detection (LOD) of 1.2 and 5.3 nM, respectively. A linear-scan cathodic stripping voltammetry (LS-CSV) methodology was developed for the joint detection of Co(II) and Ni(II) yielding LOD of 1.8 and 3.5 nM, respectively. Method validation was carried out on 14 upper B-horizon soil samples during a field survey. Two wet extraction procedures were applied for soil samples – a strong extraction using nitric acid (HNO 3 ) and a weak extraction using calcium chloride (CaCl 2 ). Excellent agreement between electroanalytical methods and inductively coupled plasma mass spectrometry (ICP-MS) was found for Pb(II), while a small underestimation was observed for Zn(II). For Co(II) and Ni(II) the LS-CSV measurements in the HNO 3 extractions were impossible due to the change from low pH to pH to 7.15 which induces precipitation of iron and aluminium. For the CaCl 2 extractions, the Co(II)/Ni(II) results obtained by LS-CSV were in excellent agreement with ICP-MS measurements.

Core-shell niobium(v) oxide@molecularly imprinted polythiophene nanoreceptors for transformative, real-time creatinine analysis.

Creatinine, a byproduct of muscle metabolism, is typically filtered by the kidneys. Deviations from normal concentrations of creatinine in human saliva serve as a crucial biomarker for renal diseases. Monitoring these levels becomes particularly essential for individuals undergoing dialysis and those with kidney conditions. This study introduces an innovative disposable point-of-care (PoC) sensor device designed for the prompt detection and continuous monitoring of trace amounts of creatinine. The sensor employs a unique design, featuring a creatinine-imprinted polythiophene matrix combined with niobium oxide nanoparticles. These components are coated onto a screen-printed working electrode. Thorough assessments of creatinine concentrations, spanning from 0 to 1000 nM in a redox solution at pH 7.4 and room temperature, are conducted using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The devised sensor exhibits a sensitivity of 4.614 μA cm-2 nM-1, an impressive trace level limit of detection at 34 pM, and remarkable selectivity for creatinine compared to other analytes found in human saliva, such as glucose, glutamine, urea, tyrosine, etc. Real saliva samples subjected to the sensor reveal a 100% recovery rate. This sensor, characterized by its high sensitivity, cost-effectiveness, selectivity, and reproducibility, holds significant promise for real-time applications in monitoring creatinine levels in individuals with kidney and muscle-related illnesses.

Disposable Voltammetric Immunosensor for D-Dimer Detection as Early Biomarker of Thromboembolic Disease and of COVID-19 Prognosis

In this work, we report on the development of a simple electrochemical immunosensor for the detection of D-dimer protein in human plasma samples. The immunosensor is built by a simple drop-casting procedure of chitosan nanoparticles (CSNPs) as biocompatible support, Protein A (PrA), to facilitate the proper orientation of the antibody sites to epitopes as a capture biomolecule, and the D-dimer antibody onto a carboxyl functionalized multi-walled carbon nanotubes screen printed electrode (MWCNTs-SPE). The CSNPs have been morphologically characterized by Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS) techniques. Successively, the electrochemical properties of the screen-printed working electrode after each modification step have been characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The resulting MWCNTs-CSNPs-PrA-D-dimer Ab immunosensor displays an optimal and promising platform for antibody immobilization and specific D-dimer detection. DPV has been used to investigate the antigen/antibody interaction at different D-dimer concentrations. The proposed voltammetric immunosensor allowed a linear range from 2 to 500 μg L-1 with a LOD of 0.6 μg L-1 and a sensitivity of 1.3 μA L μg-1 cm-2. Good stability and a fast response time (5 s) have been reported. Lastly, the performance of the voltammetric immunosensor has been tested in human plasma samples, showing satisfactory results, thus attesting to the promising feasibility of the proposed platform for detecting D-dimer in physiological samples.

Facile fabrication of screen-printed MoS2 electrodes for electrochemical sensing of dopamine

Molybdenum disulfide (MoS2) screen-printed working electrodes were developed for dopamine (DA) electrochemical sensing. MoS2 working electrodes were prepared from high viscosity screen-printable inks containing various concentrations and sizes of MoS2 particles and ethylcellulose binder. Rheological properties of MoS2 inks and their suitability for screen-printing were analyzed by viscosity curve, screen-printing simulation and oscillatory modulus. MoS2 inks were screen-printed onto conductive FTO (Fluorine-doped Tin Oxide) substrates. Optical microscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX) analysis were used to characterize the homogeneity, topography and thickness of the screen-printed MoS2 electrodes. The electrochemical performance was assessed through differential pulse voltammetry. Results showed an extensive linear detection of dopamine from 1 µM to 300 µM (R2 = 0.996, sensitivity of 5.00 × 10–8 A μM−1), with the best limit of detection being 246 nM. This work demonstrated the possibility of simple, low-cost and rapid preparation of high viscosity MoS2 ink and their use to produce screen-printed FTO/MoS2 electrodes for dopamine detection.

Fabrication and characterization of Prussian blue screen-printed working electrode and their application for free chlorine monitoring in swimming pool water

A Prussian blue screen-printed working electrode (PB-SPWE) was fabricated for continuous detection of free chlorine compound (free-Cl) in water samples from swimming pools. Carbon and Prussian blue were deposited on a flexible substrate using a screen-printing technique. Different screen-printed PB-SPWEs demonstrated the good reproducibility of the electrode fabrication and were further incorporated with a lab-made flow cell in a flow injection (FI) analysis system. The electrochemical response via Prussian blue reaction was recorded at a potential of 50 mV vs. Ag/AgCl. High-throughput analysis was achieved by continuous injection of a standard NaOCl solution, and 336 measurements could be completed in 5.6 h. Under optimal conditions, the PB-SPWE was applied to determine free-Cl in several swimming pool water samples without any sample preparation. The results not only were in good agreement with the standard DPD (N,N‑diethyl-p-phenylenediamine) spectrophotometric method, but also presented excellent accuracy (recovery = 80.0 ± 0.2 to 109±1%) and precision (test by Wilcoxon Signed-Ranks) in measuring free-Cl concentrations. In summary, these results supported that the combination of PB-SPWE and FI-AMP can be applied to monitor swimming pool water quality, which can minimize the risk to swimmers’ health.

3D printed microcell featuring a disposable nanocomposite Sb/Sn immunosensor for quantum dot-based electrochemical determination of adulteration of ewe/goat’s cheese with cow’s milk

Abstract This work describes a new type of electrochemical immunosensing device which consists of a 3D printed mini cell integrating two thermoplastic electrodes and a disposable graphite screen-printed working electrode modified with Sb2O5/SnO2. The applicability of the immunodevice to the analysis of complex matrices is demonstrated through the assessment of adulteration of cheese produced from ewe/goat’s milk with cow’s milk. The operation of the device is based on: (i) the development of a competitive immunoassay onto the surface of the screen-printed working electrode using biotinylated anti-bovine k-casein labeled with streptavidin-conjugated CdSe/ZnS quantum dots (QDs) and (ii) the stripping voltammetric detection of Cd(II) released after the acidic dissolution of Cd-based QDs. Determination is carried out at the screen-printed working electrode covered with Sb/Sn nanoparticles formed in-situ by reduction of the embedded precursors (Sb2O5/SnO2) simultaneously with the deposition of Cd on the surface of the working electrode. Under the selected experimental variables, the limit of detection was 0.07 % (v/v) cow’s milk in ewe/goat’s cheese. The synergistic combination of 3D printing, QD labeling and in-situ formation of nanostructured sensing surface, establishes the proposed sensor as an easy-constructed and ultrasensitive immunodetection device with wide scope of applicability to other QDs-based bioassays.

Screen-printed anion-exchange solid-phase extraction: A new strategy for point-of-care determination of angiotensin receptor blockers

A miniaturized system of anion exchange solid phase extraction (SPE) based on a screen-printed electrode was developed as a point of care (POC) device for extraction and quantitative determination of anionic analytes. Nylon 6/polyaniline nanofibers were fabricated by electrospinning and in-situ oxidative polymerization techniques coated on a screen-printed working electrode and characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. The effects of essential parameters such as desorption conditions, pH of the sample solution, adsorption voltage, adsorption time, and salt concentration on the performance of the method were investigated. To evaluate the performance of the system, angiotensin ΙΙ receptor antagonists, including valsartan, losartan, and irbesartan, were selected as model compounds and analyzed by HPLC/UV after extraction. The limits of detection and quantification were ranging between 0.4 and 0.9 μg L−1 and 1.3–3.0 μg L−1, respectively. The linear dynamic range for Losartan, Irbesartan, and Valsartan was 2–400, 4–1000, and 2–400 μg L−1, respectively, with R2 > 0.991. Finally, the method was applied for the determination of ARA-IIs in human blood plasma samples, and relative recoveries in the range of 89.0–107.8% with relative standard deviation (RSDs (≤8.9% were obtained.

Electrochemical sensory detection of Sus scrofa mtDNA for food adulteration using hybrid ferrocenylnaphthalene diimide intercalator as a hybridization indicator.

In this study, an electrochemical DNA biosensor was developed based on the fabrication of silicon nanowires/platinum nanoparticles (SiNWs/PtNPs) on a screen-printed carbon electrode (SPCE) for the detection of Sus scrofa mitochondrial DNA (mtDNA) in food utilizing a new hybrid indicator, ferrocenylnaphthalene diimide (FND). The morphology and elemental composition of the SiNWs/PtNPs-modified SPCE was analyzed by field emission scanning electron microscopy (FESEM) combined with energy dispersive X-ray spectroscopy (EDX). Cyclic voltammetry (CV) was used to study the electrical contact between the PtNPs and the screen-printed working electrode through SiNWs, while electrochemical impedance spectroscopy (EIS) was used to measure the charge transfer resistance of the modified electrode. The results clearly showed that the SiNWs/PtNPs were successfully coated onto the electrode and the effective surface area for the SiNWs/PtNPs-modified SPCE was increased 16.8 times as compared with that of the bare SPCE. Differential pulse voltammetry used for the detection of porcine DNA with FND as an intercalator confirmed its specific binding to the double-stranded DNA (dsDNA) sequences. The developed biosensor showed a selective response towards complementary target DNA and was able to distinguish non-complementary and mismatched DNA oligonucleotides. The SiNWs/PtNPs-modified SPCE that was fortified with DNA hybridization demonstrated good linearity in the range of 3 × 10−9 M to 3 × 10−5 M (R2 = 0.96) with a detection limit of 2.4 × 10−9 M. A cross-reactivity study against various types of meat and processed food showed good reliability for porcine samples.

Electrochemical enzyme-linked oligonucleotide array for aflatoxin B1 detection

In this work, an electrochemical enzyme-linked oligonucleotide array to achieve simple and rapid multidetection of aflatoxin B1 (AFB1) is presented. The assay is based on a competitive format and disposable screen-printed cells (SPCs). Firstly, the electrodeposition of poly(aniline-anthranilic acid) copolymer (PANI-PAA) on graphite screen-printed working electrodes was performed by means of cyclic voltammetry (CV). Aflatoxin B1 conjugated with bovine serum albumin (AFB1-BSA) was then immobilized by covalent binding on PANI-PAA copolymer. After performing the affinity reaction between AFB1 and the biotinylated DNA-aptamer (apt-BIO), the solution was dropped on the modified SPCs and the competition was carried out. The biotinylated complexes formed onto the sensor surface were coupled with a streptavidin-alkaline phosphatase conjugate. 1-naphthyl phosphate was used as enzymatic substrate; the electroactive product was detected by differential pulse voltammetry (DPV). The response of the enzyme-linked oligonucleotide assay was signal-off, according to the competitive format. A dose-response curve was obtained between 0.1 ng mL−1 and 10 ng mL−1 and a limit of detection of 0.086 ng mL−1 was achieved. Finally, preliminary experiments in maize flour samples spiked with AFB1 were also performed.

Electrochemical integrated paper-based immunosensor modified with multi-walled carbon nanotubes nanocomposites for point-of-care testing of 17β-estradiol

17β-estradiol (17β-E2) plays a critical role in regulating reproduction in human, there is therefore an urgent need to detect it sensitively and precisely in a cost-effective and easy method. In this paper, a label-free integrated microfluidic paper-based analytical device was developed for highly sensitive electrochemical detection of 17β-E2. The microfluidic channel of the paper-based sensor was fabricated with wax printing and the three electrodes, including working, counter and reference electrode were screen-printed. Multi-walled carbon nanotubes (MWCNTs)/ thionine (THI)/ gold nanoparticles (AuNPs) Nano composites were synthesized and coated on screen-printed working electrode (SPWE) for the immobilization of anti-E2. In this electro-chemical system of paper-based immunoassay, THI molecules serving as an electrochemical mediator while MWCNTs and AuNPs, due to their excellent electrical conductivities, could accelerate electron transfer for the signal amplification. Experimental results revealed that the immunoassay is able to detect 17β-E2 as low as 10 pg mL−1, with a linear range from 0.01 to 100 ng mL−1. This microfluidic paper-based immunosensor would provide a new platform for low cost, sensitive, specific, and point-of-care diagnosis of 17β-E2.

A sensitive nitrite sensor using an electrode consisting of reduced graphene oxide functionalized with ferrocene

A composite consisting of chitosan containing azidomethylferrocene covalently immobilized on sheets of reduced graphene oxide was drop-casted on a polyester support to form a screen-printed working electrode that is shown to enable the determination of nitrite by cyclic voltammetry and chronoamperometry. Both reduction and oxidation of nitrite can be accomplished due to the high electron-transfer rate of this electrode. Under optimal experimental conditions (i.e. an applied potential of 0.7 V vs. Ag/AgCl in pH 7.0 solution), the calibration plot is linear in the 2.5 to 1450 μM concentration range, with an ~0.35 μM limit of detection (at a signal-to-noise ratio of 3). The sensor was successfully applied to the determination of nitrite in spiked mineral water samples, with recoveries ranging between 95 and 101 %.

A novel label-free microfluidic paper-based immunosensor for highly sensitive electrochemical detection of carcinoembryonic antigen

In this work, a highly sensitive label-free paper-based electrochemical immunosensor employing screen-printed working electrode (SPWE) for detection of carcinoembryonic antigen (CEA) was fabricated. In order to raise the detection sensitivity and immobilize anti-CEA, amino functional graphene (NH2-G)/thionine (Thi)/gold nanoparticles (AuNPs) nanocomposites were synthesized and coated on SPWE. The principle of the immunosensor determination was based on the fact that the decreased response currents of Thi were proportional to the concentrations of corresponding antigens due to the formation of antibody–antigen immunocomplex. Experimental results revealed that the immunoassay enabled the determination of standard CEA solutions with linear working ranges of 50pgmL−1 to 500ngmL−1, the limit of detections for CEA is 10pgmL−1 (S/N=3) and its corresponding correlation coefficients were 0.996. Furthermore, the proposed immunosensor could be used for the determination of clinical serum samples. A large number of clinical serum samples were detected and the relative errors between measured values and reference concentrations were calculated. Results showed that this novel paper-based electrochemical immunosensor could provide a new platform for low cost, sensitive, specific, and point-of-care diagnosis in cancer detection.

Comparison of different modifications of screen-printed working electrodes of electrochemical sensors using carbon nanotubes and plasma treatment

The screen-printed working electrode (WE) of an electrochemical sensor was modified with multi-walled carbon nanotubes (MWCNTs) and a plasma treatment. The plasma treatment was performed using radio frequency capacitively coupled discharge in Ar/O2, Ar/cyclopropylamine and Ar/NH3. The surface of the WEs was characterized by scanning electron microscopy and their electrochemical behaviours were studied using potassium ferro/ferricyanide and dopamine as standard electrochemical probes. The most promising results were obtained with the electrodes modified by oxygen plasma because the reversibility and the current response were both improved significantly. The peak-to-peak separation improved from 879 to 116 mV after the oxygen plasma treatment of the bare DuPont 7102 electrode. Spray-coated MWCNTs had a positive effect on the performance of the screen-printed DuPont 7102 WE if the sprayed MWCNTs layer was thicker. However, this improvement did not reach the performance of the screen-printed DuPont electrode modified by plasma oxidation. The modification by Ar/NH3 had weak influence on the response depending on the type of the electrode and plasma treatment in Ar/cyclopropylamine plasma led to an inhibition of the electrochemical reactivity due to a preparation of too thick insulating film. MWCNTs modified screen-printed disposable electrochemical microsensor for trace detection of various substances in a droplet.

Determination of the antiradical properties of olive oils using an electrochemical method based on DPPH radical

The present work describes the development of an electrochemical method based on the use of 2,2′-diphenyl-1-picrylhidrazyl free radical (DPPH) for the determination of the antiradical properties of several olive oils. Differential pulse voltammetry was used as measuring technique while the electrochemical process was recorded at a platinum screen-printed working electrode. The decrease in 2,2′-diphenyl-1-picrylhidrazyl peak current intensity was measured at a specific potential value of +160mV vs. screen-printed pseudo-reference electrode, in the presence of α-, δ- and γ-tocopherol and olive oil samples, respectively. The obtained results using differential pulse voltammetry, as detection technique for real samples analysis, showed a satisfactory agreement with those obtained by high-performance liquid chromatography coupled with fluorescence detection. The reported electrochemical method is rapid and easy to use, feasible and accessible to be used as an alternative to 2,2′-diphenyl-1-picrylhidrazyl spectrophotometric based method.

An origami electrochemiluminescence immunosensor based on gold/graphene for specific, sensitive point-of-care testing of carcinoembryonic antigen

In this work, an electroluminescence (ECL) immunosensor was introduced into a folding cellulose fiber paper based on gold/graphene modified screen-printed working electrode (SPWE) to develop an ECL microfluidic origami immunodevice. Graphene was used to modify the working electrode for its fast electron transportation, excellent mechanical stiffness and good biocompatibility. A dense gold layer was formed for the first time through the growth of gold nanoparticles on the graphene layer, to further enhance the sensitivity, stability and effective surface area of the SPWE. On this as-prepared SPWE, phenyleneethynylene derivative modified nanotubular mesoporous Pt–Ag alloy nanoparticles were used as signal amplifier for the highly sensitive determination of carcinoembryonic antigen in human serum sample in the linear range from 0.001 to 100ngmL−1 with a low detection limit of 0.3pgmL−1. The specificity, reproducibility, and stability of this microfluidic origami ECL immunodevice (μ-OECLID) were investigated in this work. This novel μ-OECLID would provide a new platform for low cost, sensitive, specific, multiplex assay and point-of-care diagnosis in public health, environmental monitoring, and the developing world.

Determination of total and electrolabile copper in agricultural soil by using disposable modified-carbon screen-printed electrodes

The objective of the study is to evaluate modified-carbon screen-printed working electrodes (SPE) combined with square wave anodic stripping voltammetry (SWASV) to determine electrolabile and total copper in soils with the perspective to assess the environmental hazard resulting from copper anthropogenic contamination. The voltammetric method was investigated using a mineralized certified reference soil such that it can be assumed that the copper was totally under electrolabile form in the solution of mineralized soil. In optimal conditions, a copper recovery of 97% and a relative standard deviation (RSD) of 9% were found. The limits of detection and quantification for copper were 0.4 and 1.3 μg L(-1), respectively. Finally, the method was applied on soil leachates, which allowed evaluating the cupric transfer from the soil to the leachates and quantifying the electrolabile copper part in leachates.

Simultaneous determination of cadaverine and putrescine using a disposable monoamine oxidase based biosensor

The selective and simultaneous amperometric determination of putrescine (Put) and cadaverine (Cad) has been carried out using a novel design of screen-printed carbon electrode (SPCE) with two working electrodes connected in array mode. A mixture of 3% of tetrathiafulvalene (TTF), as mediator, and carbon ink was used for the construction of the screen-printed working electrode. The employment of different amounts of monoamine oxidase (MAO) enzyme on these modified TTF/SPCEs and the use of gold nanoparticles (AuNPs) allowed performing the simultaneous determination of both analytes. The amperometric detection has been performed by measuring the oxidation current of the mediator at a potential of+250 mV vs. screen-printed Ag/AgCl reference electrode. A linear response in the Cad concentration range from 19.6 till 107.1 µM and from 9.9 till 74.1 μM for Put was obtained at the MAO/AuNPs/TTF/SPCE biosensor. This device showed a capability of detection of 9.9 and 19.9±0.9 µM (n=4 α=β=0.05) and a precision of 4.9% and 10.3% in terms of relative standard deviation for Put and Cad, respectively. The developed biosensor was successfully applied to the simultaneous determination of Put and Cad in octopus samples.

An Immunosensor for Microcystins Based on Fe3O4 @Au Magnetic Nanoparticle Modified Screen-Printed Electrode

Abstract Coreshell Fe3O4@Au magnetic nanoparticles (NPs) were modified onto the surface of the screen-printed working electrode, and the antibody of microcystin-(leucine-arginine) (anti-MCLR) was immobilized on the film surface of Fe3O4@Au NPs by the adsorption between Au nanoparticles and antibody. Subsequently, bovine serum albumin (BSA) was used to block the non-specific adsorption sites of the electrode to obtain immunosensor for the detection of MCLR. The immunosensor was based on the direct competitive immunoassay format between the labeled agent of horseradish peroxidase-conjugated MCLR (MCLR-HRP) and the analyte. MCLR was determined by differential pulse voltammetry (DPV). Under the optimal experimental conditions, the peak current response decreased proportionally with the concentration of MCLR in the range of 0.79−12.9 μg L−1 with a detection limit of 0.38 μg L−1. The developed biosensor was used to determine MCLR in real water samples with the recoveries of standard additions of 95% – 107%. The proposed immunosensor possesses the properties of fast, sensitive and portable, etc.

A novel microfluidic origami photoelectrochemical sensor based on CdTe quantum dots modified molecularly imprinted polymer and its highly selective detection of S-fenvalerate

Driven by the urgent demand of high-selectively point-of-care testing device for pesticide, molecular imprinting-photoelectrochemistry (MI-PEC) was introduced into microfluidic paper-based analytical strategy to design a novel paper-based photoelectrochemical (paper-based PEC) protocol. The MI-PEC strategy was constructed based on CdTe quantum dots dotted molecular imprinted polymers (CdTe QDs@MIPs), and triggered by a common ultraviolet lamp (∼365nm, 50$). The paper-based PEC sensor was fabricated by immobilizing CdTe QDs@MIPs on paper-based screen-printed working electrodes (WEs) via gold nanoparticles (Au NPs), which was electrodeposited on the surface of WE to improve the electron transfer efficiency for high sensitivity. Using S-fenvalerate as model analyte, the produced photocurrent from the proposed paper-based MI-PEC sensor upon ultraviolet radiation decreased with the increasing concentrations of S-fenvalerate solution, and the quenched paper-based MI-PEC showed a low detection limit of 3.2×10−9molL−1. This study has made a successful attempt in the development of highly selective and sensitive photoelectrochemical sensor for S-fenvalerate monitoring.

A screen-printed disposable biosensor for selective determination of putrescine

We have developed screen-printed carbon electrodes for the determination of putrescine (Put) via the enzyme monoamine oxidase that was immobilized on the surface of the electrode by cross-linking it with bovine serum albumin using glutaraldehyde. A mixture of 5 % of tetrathiofulvalene (TTF) and carbon ink was used for the fabrication of the screen-printed working electrode. Put was amperometrically detected by measurement of the current due to the oxidation of the mediator TTF. The use of TTF lowers the working potential to +250 mV (vs. a screen-printed Ag/AgCl reference electrode). Response is linear in the range from 16 to 101 μM, and the detection limit is 17.2 ± 4.6 μM, with a reproducibility of 9.6 % (n = 4) in terms of relative standard deviation. The effects of potentially interfering biogenic amines such as cadaverine, histamine, spermine, spermidine and tryptamine were also evaluated. The biosensor was successfully applied to the determination of Put in zucchini and anchovies.