Surface Of Screen-printed Electrode Research Articles

Expanding the possibilities of electrografting modification of voltammetric sensors through two complementary strategies

Two different modification strategies by means of aryl diazonium salt electrografting were compared for the development of voltammetric sensors. In this sense, l-cysteine was immobilized onto a screen-printed carbon-based electrode surface through either its –NH2 or its –COOH group and the performance of the resulting modified sensors was tested for the simultaneous determination of Pb(II) and Cd(II) by anodic stripping voltammetry. The results obtained indicate that attachment through the –COOH group of cysteine, despite being a much less frequent electrografting strategy, improves the analytical performance of the resulting sensor achieving lower LODs, at low μg L−1 levels, for Cd(II) and Pb(II). Furthermore, this strategy allows the quantification of both metal ions below the legal limits established by the European Water Framework Directive, which represents a great improvement with respect to similar sensors reported in the literature.

A Novel Electrochemical Sensor Based on Plastic Antibodies for Vitamin D3 Detection in Real Samples

A highly sensitive voltammetric sensor for vitamin D3 is designed and build by the electropolymerization of molecularly imprinted polymer (MIP). Vitamin D3 selective MIP is synthesized by the electropolymerization of p-phenylenediamine–resorcinol mixture on the screen-printed carbon electrode (SPCE) surface in the presence of the vitamin D3 molecules. The electropolymerization of monomers made a film deposition on electrode surface which absolutely suppressed the reduction of ferricyanide. The removal of the vitamin D3 creates the cavities which caused noticeably increased ferricyanide signal, which was again suppressed after the rebinding of vitamin D3. It was shown that the decrease of the ferricyanide peak of the MIP electrode was affected linearly by vitamin D3 concentration. Various factors, by which the response current of the electrode is mainly affected, were studied and optimized. This sensor shows a linear response range of $1 \times 10^{-11}$ – $2 \times 10^{-9}$ M and lower detection limit of $1 \times 10^{\mathbf {-12}}$ M. The sensor was successfully applied for the detection of vitamin D3 in human plasma samples.

Development of Novel and Highly Specific ssDNA-Aptamer-Based Electrochemical Biosensor for Rapid Detection of Mercury (II) and Lead (II) Ions in Water

In this work, we report on the development of an electrochemical biosensor for high selectivity and rapid detection of Hg2+ and Pb2+ ions using DNA-based specific aptamer probes labeled with ferrocene (or methylene blue) and thiol groups at their 5′ and 3′ termini, respectively. Aptamers were immobilized onto the surface of screen-printed gold electrodes via the SH (thiol) groups, and then cyclic voltammetry and impedance spectra measurements were performed in buffer solutions with the addition of HgCl2 and PbCl2 salts at different concentrations. Changes in 3D conformation of aptamers, caused by binding their respective targets, e.g., Hg2+ and Pb2+ ions, were accompanied by an increase in the electron transfer between the redox label and the electrode. Accordingly, the presence of the above ions can be detected electrochemically. The detection of Hg2+ and Pb2+ ions in a wide range of concentrations as low as 0.1 ng/mL (or 0.1 ppb) was achieved. The study of the kinetics of aptamer/heavy metal ions binding gave the values of the affinity constants of approximately 9.10−7 mol, which proved the high specificity of the aptamers used.

Immunosensor for Early Diabetes Markers

To increase detection sensitivity, sensor surface modifications with various nanomaterials or selective isolation of analytes from complex clinical sample matrices by nanomaterials for amplified detection have been developed. As a novel class of two-dimensional nanocarbon material, graphene has recently attracted researchers in biomedical sciences for the development of electrochemical and optical devices. The high surface area to volume ratio, electrical conductivity, and aqueous dispersibility suitable for screen-printed electrode surfaces, thin structure and apparent biocompatibility of carboxylated graphene makes it a unique carbon nanomaterial for biosensing applications. Although, glucose and insulin biosensors are useful for diabetes management, non-glucose biomarkers are critical for potentially enabling early diabetes detection in children and adults. We present herein a quantitative comparison between carboxylated graphene and mercapto-monolayer surface for measuring serum glutamic acid decarboxylase-65 autoantibody, a biomarker of type 1 diabetes, by an electrochemical immunoassay design combined with surface plasmon binding kinetics. Knowledge gained from the combined sensing and binding assessment is useful for reliable large-scale production of clinical immunosensors for biomarker based diagnostic assays.

Dual-modality impedimetric immunosensor for early detection of prostate-specific antigen and myoglobin markers based on antibody-molecularly imprinted polymer

A new dual-modality immunosensor based on molecularly imprinted polymer (MIP) and a nanostructured biosensing layer has fabricated for the simultaneous detection of two important markers including prostate-specific antigen (PSA) and myoglobin (Myo) in human serum and urine samples. In the first step, 3,3′-dithiodipropionic acid di(N-hydroxysuccinimide ester) (DSP) was self-assembled on a gold screen printed electrode (SPE). Then, the target proteins were attached covalently to the DSP-SPE. The imprinted cocktail polymer ((MIP(PSA, Myo)-SPE)) was synthesized at the SPE surface using acrylamide as monomer, N,N′-methylenebisacrylamide as a crosslinker, and PSA and Myo as the templates, respectively. The MIP-SPE was specific for the impedimetric sensing of PSA and Myo. After that, a nanocomposite (NCP) was synthesized based on the decorated magnetite nanoparticles with multi-walled carbon nanotube, graphene oxide and specific antibody for PSA (Ab). Then, NCP incubated with (MIP(PSA, Myo)-SPE. The modified electrodes and synthesized nanoparticles were characterized using electrochemical impedance spectroscopy, dynamic light scattering, surface plasmon resonance and scanning electron microscopy. The limits of detections were found to be 5.4 pg mL−1 and 0.83 ng mL−1 with the linear dynamic ranges of 0.01–100 and 1–20000 ng mL−1 for PSA and Myo, respectively. The ability of proposed biosensor to detect PSA and Myo simultaneously with high sensitivity and specificity offers a powerful opportunity for the new generation of biosensors. This dual-analyte specific receptors-based device is highly desired for the integration with lab-on-chip kits to measure a wide panel of biomarkers present at ultralow levels during early stages of diseases progress.

Electrochemical sensing of ecstasy with electropolymerized molecularly imprinted poly(o-phenylenediamine) polymer on the surface of disposable screen-printed carbon electrodes

This study demonstrates the ability of an electrochemical sensor based on molecularly imprinted polymers (MIPs) to selectively quantify 3,4-methylenedioxymethamphetamine (MDMA), also known as ecstasy, in biological samples. The device was constructed using ortho-phenylenediamine (o-PD) as the MIP’s building monomer at the surface of a screen-printed carbon electrode (SPCE). The step-by-step construction of the SPCE-MIP sensor was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Density functional theory (DFT) calculations and modelling were performed not only to understand template-monomer interaction but also to comprehend which possible polymer structure - linear or ramified poly(o-PD) – indeed interacts with the analyte. The prepared sensor worked by directly measuring the MDMA oxidation signal through square-wave voltammetry (SWV) after an incubation period of 10 min. Several parameters were optimized, such as the monomer/template ratio, the number of electropolymerization scanning cycles, and the incubation period, to obtain the best sensing efficiency. Optimized sensors exhibited suitable selectivity, repeatability (2.6%), reproducibility (7.7%) and up to one month of stable response. A linear range up to 0.2 mmol L−1 was found with an r2 of 0.9990 and a limit of detection (LOD) and quantification (LOQ) of 0.79 and 2.6 μmol L−1 (0.15 and 0.51 μg mL−1), respectively. The proposed sensor was successfully applied to human blood serum and urine samples, showing its potential for application in medicine and in forensic sciences.

High performance of electrochemical and fluorescent probe by interaction of cell and bacteria with pH-sensitive polymer dots coated surfaces

Using pH-switchable fluorescent polymer dots (PD) by means of fluorescent, colorimetric, and electrochemical signals generated from surfaces coated with PD of zwitterionic structure provided a fast and easy method to assess their performance in mammalian cell and bacterial interactions. The PD-coated surfaces showed high sensitivity over a broad range of pH levels by switching reversibly zwitterionic states, which led to an excellent cellular resistance effect by inhibiting the attachment of nearly 95% of mammalian cells. Similarly, they exhibited a strong interaction with the negatively charged surfaces of bacteria, as observed in the fluorescence ON/OFF system. In addition, PD were employed to detect the attachment of mammalian and bacterial cells: we deposited PD on a screen-printed carbon electrode for cyclic voltammetry analysis. Notably, the presence of cells remarkably interfered with the current flow between the PD and the screen-printed carbon electrode surface by causing an impressive decline in both reduction-oxidation signals, implying the high sensitivity of the PD-coated surfaces to cells and bacteria in different pH environments. Therefore, as smart materials with high sensitivity, biocompatibility, selectivity, and accuracy, PD-coated surfaces represent a promising approach to visualizing and controlling biological cell attachment, thereby helping to avoid contamination in biomedical applications.

Extended coverage of screen-printed graphite electrodes by spark discharge produced gold nanoparticles with a 3D positioning device. Assessment of sparking voltage-time characteristics to develop sensors with advanced electrocatalytic properties

Graphite screen-printed electrodes (SPEs) were modified with gold nanoparticles (AuNPs) produced by electric spark discharge between the SPE and a gold-silicon eutectic alloy (eAu/Si) tip electrode, under atmospheric conditions at 1.2 kV DC using a fully automated procedure. The automation was based on a 3D positioning device, which allowed to precisely adjust the sparking distance and to achieve regular spacing of a predetermined number of sparks across the surface of SPEs (d = 3 mm) by controlling the movement of the eAu/Si tip. Moreover, the effect of voltage-time characteristics of the produced discharges on the morphological and electroanalytical properties of the sparked-modified SPEs was investigated by setting the values of capacitors in the high voltage multiplier cascade, and at the power supply output. It is shown that under specific variables the underlying carbon layer is not appreciably damaged by the spark discharges and does not contribute to electrochemical responses of sparked SPEs, i.e., the active electrode surface has been entirely covered by AuNPs. Sparked surfaces were extensively characterized by scanning electron microscopy and various electrochemical techniques, while the electroanalytical utility of eAu/Si-sparked SPE was investigated with ascorbic acid as a pilot analyte. Advanced electrocatalytic activity is documented by an extreme shift of ascorbate oxidation overpotential (Ep = 89 mV at eAu/Si-sparked SPE) with respect to both bare SPE (Ep = 503 mV) and bulk gold electrode (Ep = 358 mV). Simultaneous differential pulse voltammetric sensing of ascorbic and uric acids in human urine is also demonstrated.

A catholically pre-treated low cost screen-printed carbon electrode surface for metal compounds electrocatalyst like hydrogen evolution activity

Search for simple and economical electrocatalyst for the hydrogen gas evolution reaction (HER), which can resemble to the performance of Pt and other precious metals, is a challenging research interest. In this work, a systematic effect of pre-treatment potential of screen-printed carbon (SPCE) surface on the HER performance in 0.5 M H2SO4 was carried out. A new observation of a low potential HER (onset potential, Eonset = −0.02 V vs. RHE) at a cathodic potential, −0.5 V vs. Ag/AgCl on 1 hr pre-treated screen-printed carbon electrode (SPCE*, * = pre-treated) was observed. Physicochemical and electrochemical characterizations of the SPCE* by field emission scanning electron-microscope, Raman, IR and X-Ray photoelectron spectroscopes reveals specific generation of carboxylic acid functionalized carbon surface and in turn for the enhanced HER on the modified electrode surface. Electrochemical characterization of SPCE* with Fe(CN)63− support the observation. A marked decrement in the peak current and significant increase in the peak-to-peak separation potential response due electrostatic repulsion between the anion sites of Fe(CN)63− and –COO– were noticed. This observation is in parallel with the reduced electrical double layer capacitance value of the SPCE* system. The Eonset and Tafel value (54.7 mV dec−1) obtained here are comparable to those at Pt, MoS2, MoSe2 and superior over the N- and P-doped graphene/carbon electrocatalysts for HER. A prototype HER system was developed and demonstrated for H2 gas production at a rate of 0.0053 μM s−1 (Operating potential = −0.5 V vs Ag/AgCl), which is comparable to that of precious metal and metal compound electrocatalysts based HER performance.

Electrochemical aptasensor based on one step co-electrodeposition of aptamer and GO-CuNPs nanocomposite for organophosphorus pesticide detection

In this work, aptamer (Apt) immobilized on sensing interface utilizing one step co-electrodeposition technology was first proposed and applied in an electrochemical aptasensor to detect organophosphorus pesticide. This method was simple and facile, solving the complicated problem of aptasensor preparation process. Specifically, in the preparation of the electrodeposition solution, graphene oxide (GO) was used to connect aptamer modified with NH2, offering the basis for aptamer fixation. And, the introduction of Cu nanoparticles (CuNPs) into the Apt-GO mixed solution enhanced the conductivity of the electrodeposition film, leading to superior electrochemical performance. In addition, during electrodeposition of the prepared solution on screen-printed carbon electrode (SPCE) surface by CV technology, GO was electrochemically reduced to reduced graphene oxide (rGO), providing better electrical conductivity. The Apt/rGO-CuNPs composite coating was characterized using SEM and CV technique. Under the optimal experimental conditions, the low detection limit of 0.003 nM for profenofos, 0.3 nM for phorate, 0.03 nM for isocarbophos and 0.3 nM for omethoate were obtained. The aptasensor was also successfully applied for the analysis of phorate in vegetables. Because the developed aptasensor with simple preparation process had extremely good stability, high selectivity and great sensitivity, it would show great potential for other fields.

Electrochemical inhibition biosensor array for rapid detection of water pollutions based on bacteria immobilized on screen-printed gold electrodes

This work reports on the development of a bacteria-based inhibition biosensor array for detection of different types of pollutions, i.e. heavy metal ions (Zn 2+ ), pesticides (DDVP) and petro-chemicals (pentane), in water. The biosensor chip for preliminary identification of the above water pollutants is based on three types of bacteria (Escherichia coli, Shewanella oneidensis and Methylosinus trichosporium OB3b) immobilized on screen-printed gold electrode surface via poly L-lysine which provides strong adhesion of bacterial monolayer to the electrode without losses of biological function. A series of optical measurements and DC electrochemical measurements were carried out on these three types of bacteria species immobilized on modified screen printed gold electrodes as well as on the bacteria in solution samples. The principle of electrochemical detection of pollutants is based on the facts that live bacteria adsorbed (or immobilized) on the electrode surface appeared to be insulating and thus reducing the electrochemical current, while the bacteria damaged by pollutants are less insulating. The results obtained demonstrated different effects of the three different types of analytes studied, e.g. Zn 2+ , DDVP, and pentane, on the three bacteria used. The findings are encouraging for application of a pattern recognition approach for identification pollutants which may lead to development of a novel, simple, and cost-effective bio-sensing array for preliminary detection of environmental pollutants in water.

Surface Modification of Screen-Printed Carbon Electrode (SPCE) with Calixarene-Functionalized Electrochemically Reduced Graphene Oxide (ERGO/C4) in the Electrochemical Detection of Anthracene

In this study, electrochemically reduced graphene oxide (ERGO) and 4-tertbutylcalix[4]arene (C4) were deposited on the surface of screen-printed carbon electrodes (SPCE) to detect anthracene in aqueous solution. The formation of electrochemically reduced graphene oxide/calix[4]arene (ERGO/C4) on SPCE was characterized using Raman spectroscopy, FTIR, and FESEM. Electrochemical properties of the modified electrode were investigated by means of CV and DPV. The electrochemical response of anthracene was greatly improved on ERGO/C4-SPCE compared to bare SPCE. Under optimized condition, the anthracene peak showed a good linear relationship at a concentration ranging from 2–8 nM and a detection limit of 0.016 nM. The developed sensor was able to conserve its performance in the presence of various organic compound and inorganic metal ions and also yielded a good comparable result to the conventional method which is HPLC in real sample with acceptable recovery of 96–97%; thus proving to be a promising candidate for rapid, inexpensive, and sensitive determination of anthracene in real samples.

Development of electrochemical sensor based on aptamer specific to lung cancer tumor marker

Electrochemical aptasensor is a sensor based on an indicator electrode covered with a layer of an aptamer that is able to bind target molecules with high specificity. In this work, DNA-aptamer LC-2108 specific to lung cancer tumor marker was immobilized onto the surface of golden screen-printed and disc electrodes. The electrodes were studied by conventional electrochemical methods–cyclic voltammetry and electrochemical impedance spectroscopy. The current increase and electron transfer resistance decrease were registered. It seems as if the aptamer presence facilitated the electron transfer through the electrode-solution boundary. As the possible reasons of such an unusual electrochemical behavior we proposed the unordinary or irregular structure of the aptamer layer on the Au surface or the specific electrochemical properties of the aptamer itself.

Effect of APTES Percentage towards Reduced Graphene Oxide Screen Printed Electrode Surface for Biosensor Application

Abstract Graphene and its derivatives are popular material nowadays among researchers due to its interesting mechanical, electronic and structural properties. Although pristine graphene have high electrical conductivity, some biosensor application require modified form of graphene such as graphene oxide or reduced graphene oxide because easier attachment of linker due to their oxide layer availability. Common functionalization method is using APTES as a linker that attach to working electrode of screen printed electrode. Certain percentage of APTES will then bind with targeted biomarker. Here, silanization of 2%, 4%, 6%, 8% and 10% APTES were conducted on the surface of reduced graphene oxide screen printed electrode to study the effect of APTES percentage towards reduced graphene oxide surface for stable biosensor platform. The 2% APTES shows stable current result of 0.111µA and potential of 0.18V at 100mV/s. This result significant for concentration to surface area ratio whereby low concentration produced higher surface area and lower resistance for electron transfer.

Uric Acid Biosensor Based on Biofilm of L. plantarum using Screen-Printed Carbon Electrode Modified by Magnetite

Biosensor based on biofilm of L. plantarum has been successfully done for determination of uric acid in human urine compared with colorimetric enzymatic produced relative error of less than 5%. L. plantarum has uricase activity to react with uric acid, to maintain the stability of bacteria forming themselves into biofilms. Magnetite is known to increase sensitivity of the biosensor. The combination of magnetite-polyethylene glycol (Fe3O4-PEG) was used to modify the surface of Screen-Printed Carbon Electrode modified (SPCE) and the resulting modified electrode (biofilm/Fe3O4/PEG/SPCE) displayed good electrocatalytic activity to the oxidation of UA. The composition of biofilms with optical density 1, magnetite 100 mgmL-1 and PEG 3% v / v were able to increase the current up to 48% in 4mM of UA. The biosensor with an optimum composition produced good linearity with a concentration range, limit of detection, limit of quantitation, sensitivity, and repeatability were found to be 0.1 - 4.3 mM, 70 µM, 234 µM, 25.392 µA mM-1, 2.38%, respectively. This biosensor stable up to 49 days of measurement with the remaining activity was 90.70% and selective for interference compounds such as salt, urea, glucose, ascorbic acid. This method has a good stability, sensitivity, and potential application in clinical analysis. Keyword: biofilm, biosensor, L. plantarum, magnetite, uric acid.

Printed flexible bifunctional electrochemical urea-pH sensor based on multiwalled carbon nanotube/polyaniline electronic ink

Urea concentration and pH are two crucial parameters in food and clinical analysis. Traditional analytical methods of urea and pH determination are unsuitable for field and involve complex instrumentation or and enzyme-based assays. In this study, we used screen printing technology to prepare an electrochemical sensor with a carbon electrode modified by a multiwalled carbon nanotube/polyaniline (MWCNT/PANi) composite for the simultaneous detection of urea and pH. Urea was detected by a simple current–potential (I–V) experiment and its concentration level on the MWCNT/PANi-modified screen-printed carbon electrode (SPCE) surface was determined by cyclic voltammetry. The MWCNT/PANi-modified SPCE had a linear response (R2 = 0.99902), lower detection limit, higher selectivity, and higher sensitivity than reported biosensors. Specifically, the detection limit was 10 µM and the sensitivity was 0.38 mA mM−1 cm−2 in the urea concentration range of 10–50 µM. Chronoamperometry was applied to investigate the changes in voltage on the MWCNT/PANi-modified SPCE with varying solution pH. The sensor exhibited excellent linearity (R2 = 0.99089) and an average sensitivity of 20.63 mV/pH over a wide pH range of 2–11. Thus, the MWCNT/PANi-modified SPCE has a promising field application as a simple, bifunctional non-enzymatic sensor.

Electrochemical sensing of the thyroid hormone thyronamine (T0AM) via molecular imprinted polymers (MIPs)

Recent studies have shown that besides the well-known T3 (triiodothyronine) and T4 (thyroxine) there might be other important thyroid hormones, in particular T0AM (thyronamine) and T1AM (3-iodothyronamine). The absence of a large number of studies showing their precise importance might be explained by the limited number of analytical methodologies available. This work aims to show an electroanalytical alternative making use of electropolymerized molecularly imprinted polymer (MIPs). The MIPs' polymerization is performed on the surface of screen-printed carbon electrodes (SPCEs), using 4–aminobenzoic acid (4-ABA) as the building and functional monomer and the analyte T0AM as the template. The step-by-step construction of the SPCE-MIP sensor was studied by cyclic voltammetry (CV) and by electrochemical impedance spectroscopy (EIS). After optimization, by means of square-wave voltammetry, the SPCE-MIP showed suitable selectivity (in comparison with other thyroid hormones and catechol amines), repeatability (intra-day of 3.9%), a linear range up to 10 μmol L−1 (0.23 × 103 μg dL−1) with an r2 of 0.998 and a limit of detection (LOD) and quantification (LOQ) of 0.081 and 0.27 μmol L−1 (1.9 and 6.2 μg dL−1), respectively.

Ultrasensitive and reusable electrochemical aptasensor for detection of tryptophan using of [Fe(bpy)3](p-CH3C6H4SO2)2 as an electroactive indicator

In this paper, we report the application of a reusable electrochemical aptasensor for detection of tryptophan by using [Fe(bpy)3](p-CH3C6H4SO2)2 as an electroactive indicator and based on the target-compelled aptamer displacement. The aptasensor fabricated by self-assembling the thiolated probe on the surface of graphite screen-printed electrode modified with gold nanoparticles/multiwalled carbon nanotubes and chitosan nanocomposite (AuNPs/MWCNTs-Chit/SPE). Afterward, Trp aptamer (Apt) immobilized on the modified electrode surface through hybridization. In the absence of Trp, a sharp peak of [Fe(bpy)3](p-CH3C6H4 SO2)2 can be observed in differential pulse voltammetry (DPV) study. The introduction of Trp led to the formation of aptamer-Trp complex and dissociation of the aptamer from the DNA-Apt duplex on the electrode surface into the solution and decreases the peak current intensity of electroactive indicator. This is because, [Fe(bpy)3](p-CH3C6H4SO2)2 tends to bind to the two strands DNA. Therefore, the peak current of [Fe(bpy)3](p-CH3C6H4 SO2)2 linearly decreased with increasing the concentration of Trp over a range of 3.0 nM- 100 μM. The detection limit (3 σ) was 1.0 nM. In addition, we examined the selectivity of the constructed biosensor for tyrosine, histidine, arginine, lysine, valine and methionine that belonged to the amino acid family.The obtained results showed that the fabricated sensor had a good selectivity for Trp against the other examined amino acids. Also, the potential applicability of the aptasensor was investigated by detecting the Trp in a complex media such as human blood plasma spiked with Trp.

A reduced graphene oxide-cyclodextrin-platinum nanocomposite modified screen printed electrode for the detection of cysteine

This article presents a highly sensitive and specific new sensing platform for cysteine determination. For the fabrication of electrochemical sensor, reduced graphene oxide-β-cyclodextrin-platinum nanocomposite (GR/CD/Pt) was prepared and surface of screen-printed electrodes were bulk modified with this nanocomposite which exhibited excellent electrocatalytic activity towards the sensing of cysteine. The GR/CD/Pt was characterized using SEM, TEM, AFM, FT-IR, TGA. The electrochemical behaviour of the fabricated sensor was investigated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. During the determination of cysteine, a good electrocatalytic response current was obtained which is linear with respect to the concentration of cysteine over the range 0.5–170 μM with the limit of detection corresponding to 0.12 μM.

Nanostructured composites based on graphene and nanoparticles of cobalt in the composition of monoamine oxidase biosensors for determination of antidepressants

Amperometric monoamine oxidase biosensors based on screen-printed graphite electrodes modified with nanostructured reduced graphene oxide (RGO) composites and cobalt nanoparticles (CoNPs) were developed to determine antidepressant drug substances: tianeptine, thioridazine, and fluoxetine. Combinations of carbon nanomaterials with metal nanoparticles (nanocomposites) along with retaining the properties of individual components, also provide a new quality of the developed devices due to their joint contribution. The nanomaterial-modifier was applied to the surface of screen-printed graphite electrodes using dropwise evaporation. Fixing of RGO on the surface of the screen-printed graphite electrodes occurs due to electrostatic interaction between RGO carboxyl groups and amine groups of the amine derivative on the platform of polyester polyol (H20–NH2). The CoNPs were obtained electrochemically by the method of chronoamperometry at a potentialE= – 1.0 V and different time of their accumulation (about 50 – 60 sec) on the electrode surface. According to the data of atomic force microscopy, the predominant size of CoNPs is (40 ± 2) and (78 ± 8) nm, depending on the time of electrochemical deposition of NPs. Data of electrochemical impedance spectroscopy show that nanocomposites RGO-chitosan/CoNPs and RGO-amine derivative on the polyester polyol (H20–NH2)/CoNPs platform are characterized by the lowest values of the charge transfer resistance. The use of those nanocomposites modifying the electrode surface significantly improved the analytical characteristics of the developed biosensors providing a wider range of operating concentrations from 1 × 10–4to 5 × 10–9mol/liter, greater sensitivity coefficient, better correlation coefficient, and lower limit of the detectable concentrations. A possibility of using biosensors to control the quality of antidepressants upon determination of the main active substance in medicinal drugs and biological fluids is shown. The lower limit of detectable concentrations (7 – 9) × 10–10mol/liter is attained when using tyramine as a substrate for determination of fluoxetine, thioridazine and tianeptine, respectively.