Bare Screen-printed Carbon Electrode Research Articles

Electrospun EU/HPMC nanofibers decorated by ZIF-8 nanoparticle as the advanced electrochemical biosensor modifier for sensitive and selective detection of c-MET cancer biomarker in human plasma sample

This research presents a selective and sensitive electrochemical biosensor for the detection of the mesenchymal–epithelial transition factor (c-MET). The biosensing is based on a modification of the SPCE (screen-printed carbon electrode) with the electrospun nanofiber containing eudragit (EU), hydroxypropyl methylcellulose (HPMC), and Zeolite imidazolate frameworks (ZIF-8) nanoparticles. EU/HPMC/ZIF-8 nanofibers have presented a high capability of electron transfer, and more active surface area than bare SPCE due to synergistic effects between EU, HPMC, and ZIF-8. On the other hand, EU/HPMC nanofibers provided high porosity, flexible structures, high specific surface area, and good mechanical strength. The presence of ZIF-8 nanoparticles improved the immobilization of anti-c-MET on the modified SPCE and also resulted in increasing the conductivity. By c-MET incubation on the modified SPCE, c-MET was connected to anti-c-MET, and consequently the electrochemical signal of [Fe(CN)6]3-/4- as the anion redox probe was reduced. In order to investigate the structural and morphological characteristics and elemental composition of electrospun nanofibers, various characterization methods including FE-SEM, XRD, FTIR, and EDS were used. Under optimum conditions with a working potential range −0.3−0.6 V (vs. Ag/AgCl), linear range (LR), correlation coefficient (R2), sensitivity, and limit of detection (LOD) were acquired at 100 fg/mL-100 ng/mL, 0.9985, 53.28 μA/cm2.dec, and 1.28 fg/mL, respectively. Moreover, the mentioned biosensor was investigated in a human plasma sample to determine c-MET and showed ideal results including reproducibility, stability, and good selectivity against other proteins.

Evaluation of electrochemical performance of antimony modified screen-printed carbon electrodes

This study compares the electrochemical performance of screen-printed carbon electrodes (SPCEs) modified with antimony (Sb/SPCEs) under different potentiostatic pre-plating conditions. Neutral Red (NR) was employed as a novel redox probe to evaluate the electrochemical performance of Sb/SPCEs. It was demonstrated that NR in the protonated form performs quasi-reversible redox transformations at bare SPCE and Sb/SPCEs in phosphate buffer solutions (pH 5.5±0.5) in the potential range of (−0.30)–(−0.75) V, where the antimony is not electroactive. Sb/SPCEs were studied electrochemically by cyclic voltammetry (CV) / electrochemical impedance spectroscopy (EIS), and morphologically by scanning electron microscopy (SEM). Cyclic voltammetry investigations revealed the dependence of the electrochemical performance of Sb/SPCEs on the degree of coverage of the substrate with the metal. The obtained CV, EIS, and SEM data are consistent. The lowest charge transfer resistance (Rct) value (6 Ω) was obtained at Sb/SPCE with the highest degree of antimony coverage. To investigate the electroanalytical performance of Sb/SPCEs, nickel (II) ions were utilized as a model analyte. A study of roughness factors and sensitivity towards nickel (II) ions for Sb/SPCEs using two-tailed Pearson's criterion revealed a high degree of correlation between their electrochemical and electroanalytical properties. The results show that using NR as a redox probe can help controlling modification processes during the development of innovative antimony-containing sensors.

Portable glucose detector based on nickel oxide modified Screen Printed Carbon Electrode (SPCE)

A portable and low-cost system prototype for glucose detector based on LMP91000EV M potentiostat has been created. Characterization of Screen-Printed Carbon Electrodes (SPCE) without modification (bare SPCE) and modified nickel oxide (NiO/SPCE) was carried out with a commercial potentiostat to see the effect of nickel oxide in detecting glucose. Through the electrochemical impedance spectroscopy method, the Rct value of 1,276.79 Ω is obtained for NiO/SPCE and 429.06 Ω for bare SPCE, so that NiO/SPCE has a slower electron transfer rate. Meanwhile, through the cyclic voltammetry method, the surface-active electrode area is 7.1×10-2cm2 for NiO/SPCE and 6.9×10-2 cm2 for bare SPCE, so that NiO/SPCE is more sensitive in detecting glucose. When the glucose concentration is varied, the Limit of Detection (LOD) and Limit of Quantitation (LOQ) values of NiO/SPCE are smaller, specifically 1.807 mM and 6.024 mM than bare SPCE, specifically 2.629 mM and 8.762 mM, so NiO/SPCE is more sensitive. When the scan rate is varied, the gradient value of NiO/SPCE is smaller, specifically -8.14×10-4 mA s/mV than bare SPCE, specifically -9.62×10-4 mA s/mV, so NiO/SPCE is not more sensitive. Next, comparing a prototype system that Trans Impedance Amplifier (TIA) gain is varied and a commercial potentiostat. As a result, the cyclic voltammogram per cycle on commercial potentiostat is more stable. The smaller the TIA gain on the system prototype, the more stable it is, this is because the noise that is amplified is getting smaller.

A study of screen-printed electrodes modified with MoSe2 and AuNPs-MoSe2 nanosheets for dopamine sensing

Molybdenum selenide nanosheets (MoSe2-NS) were synthesized by liquid-phase exfoliation (LPE) technique and successive liquid cascade centrifugation (LCC) at two different centrifugation rates (1.5 and 5 krpm). By this technique's combination, we were able to prepare MoSe2 nanosheets with different geometric characteristics (i.e., average number of layers <N> and average lateral length <L>). Increasing the centrifugation speed from 1.5 krpm to 5 krpm leads to a decrease in number of layers (down to nL = 2 – 4, with the presence of sparse monolayer flakes) and average lateral size of NS from 280 nm to 180 nm, as confirmed combining optical and morphological analysis. Modified screen-printed carbon electrodes (SPCE) with the as prepared MoSe2-NS were fabricated and applied for the determination of dopamine (DA) as an electroactive model analyte in the concentration ranging from 0.5 to 80 µM. DA is an important neurotransmitter for human beings and its deficiency can bring out various health diseases like Parkinson's and brain disorders, thus the development of simple DA sensors is highly demanding. Results demonstrated the better performances of the modified MoSe2 (5 krpm)/SPCE sensor compared to bare SPCE and the MoSe2 (1.5 krpm)/SPCE. With the objective to improve the electroanalytical performances toward dopamine, AuNPs-MoSe2-NS hybrid composite was also prepared, mixing AuNPs obtained by a green-reduction method with the MoSe2-NS. The developed AuNPs-MoSe2 (5 krpm)/SPCE sensor resulted the most promising with further improved sensitivity as compared to MoSe2/SPCE.

Electrochemical Sensitivity Improvement by the Cooperation between Pt and Ru for Total Antioxidant Evaluation in Natural Extracts

Herein, a straightforward electrochemical method was used to evaluate the total phenolic antioxidant capacity in natural extracts prepared from pomegranate, hibiscus, and pitaya. In light of this, the well-known electrochemical index (EI), a screening protocol for natural antioxidant properties evaluation, was determined using differential pulse voltammetry. Initially considering rutin and catechin as standards, we found that the system’s sensitivity greatly increased by using platinum (Pt) and platinum/ruthenium (Pt/Ru) nanoparticles (NPs) immobilized on Vulcan XC-72 to modify screen-printed carbon electrodes (SPCEs). When such modifications were applied to natural fruit/plant extracts, their electrochemical ability proved highly superior to the bare SPCE, even considering a very small amount of materials for electrode preparation. However, with an optimized ratio, the bimetallic counterpart was more sensitive to detection. When the pomegranate extract was used, for example, EI values of 52.51 ± 6.00 and 104.79 ± 6.89 µA/V were obtained using Pt and Pt/Ru (with an optimized ratio) electrocatalysts, showing the remarkable sensitivity increase obtained in our bimetallic protocol. Thus, based on physicochemical and electrochemical characterizations, we found that the ruthenium content was essential for the achievements. In due course, XPS analysis suggested that the Pt2+/Pt0 species ratio could have improved the system’s sensitivity, which significantly changed when ruthenium was used in the material.

Hollow carbon spheres decorated by silver nanocubes as the advanced aptasensing interface for sensitive and selective tracing of methamphetamine in human biofluids

This study presents a sensitive and selective aptasensor for the detection of trace amounts of MAMP. The aptasensing principle relies on modifying the planar screen-printed carbon electrode (SPCE) with the synthesized nanostructures of N-doped hollow carbon spheres (N-HCSs) and silver nanocubes (AgNCs). The nanocomposite has presented high active surface area and more electron transfer ability than bare SPCE surface. Furthermore, AgNCs in the nanocomposite acts as a linker to load high amounts of aptamer (Apt) biocaptures on the modified SPCE surface. By MAMP incubation on the embedded interface sensing, Apt arm wrapped around MAMP and the more space barrier induced on the surface and reduced the electrochemical signal of ferro/ferri cyanide as the anion redox probe. The aptasensor affinity toward MAMP led to a wide linear dynamic range (LDR) value from 1.00 pM to 50.00 mM with a low limit of detection (LOD) value of 3.33 × 10−4 pM compared to other electrochemical sensors with no significant interference from other common species. The aptasensor efficiency for MAMP measurement was satisfactory evaluated in some spiked and non-spiked serum, urine and saliva samples from a healthy and addicted person for MAMP. These acceptable results may promise the reliability of the proposed methodology for routine MAMP tests, especially saliva monitoring as the non-invasive analysis. The sensitivity and selectivity of the aptasensor, which is a bonus to accurate and valid discrimination of MAMP, holds great promise to provide technical support for routine analysis of real-world clinical samples.

Combined experimental and DFT investigation of temozolomide sensing properties of 2D− 2D interface of rich oxygen vacancies of WO3−x and sulfur-doped g-C3N4 nanosheets hybrids composites

Temozolomide (TMZ) is one of the most effective anticancer drug and higher the risk of side effects, used in overdosage in cancer treatment. It is a major concern to determine the appropriate level of the anticancer drug by a more conventional method. In the present study, the first developed 2D− 2D interface of rich oxygen vacancies of WO3 −x and sulfur-doped g-C3N4 nanosheets hybrids composites (2D–2D/RWNs-SCN) was synthesized using a facial microwave-assisted route to detection of temozolomide (TMZ) in pharmaceutical sample. The samples’ morphological, two-dimensional rich oxygen vacancies of WO3 −x nanosheets (2D RWNs) and sulfur-doped g-C3N4 nanosheets (2D SCN) were investigated using field emission-scanning electron microscopes (FE-SEM). The 2D–2D/RWNs-SCN modified screen-printed carbon electrodes (SPCEs) were utilized for reducing TMZ in a 0.1 M phosphate-buffered solution (pH 7.0). The 2D–2D/RWNs-SCN achieved a higher reduction current against TMZ than the bare SPCE, CN/SPCE, SCN/NSs/SPCE, and 2D RWNs/SPCE. With optimized sensing parameters, the limit of detection was estimated to be 0.0019 μM, with a high sensitivity of 18.2855 μA μM− 1 cm− 2. To corroborate our experimental observations qualitatively, we have first time performed detailed density functional theory simulations to explore the charge transfer and bonding mechanism of TMZ on 2D RWNs and 2D–2D/RWNs-SCN surface. The higher binding energy of TMZ and enhanced charge transfer from TMZ to 2D–2D/RWNs-SCN owing to the 2D–2D interface possess superior charge-transfer kinetics, resulting in higher TMZ sensing performance, which supports our experimental observations. The hybrid nanocomposites are successfully applied to the determination of TMZ in the presence of pharmaceutical samples.

Hierarchical 3D Snowflake-like Iron Diselenide: A Robust Electrocatalyst for Furaltadone Detection.

An electrocatalyst with a large active site is critical for the development of a high-performance electrochemical sensor. This work demonstrates the fabrication of an iron diselenide (FeSe2)-modified screen-printed carbon electrode (SPCE) for the electrochemical determination of furaltadone (FLD). It has been prepared by the facile method and systematically characterized with various microscopic/spectroscopic approaches. Due to advantageous physiochemical properties, the FeSe2/SPCE showed a low charge-transfer resistance value of 200 Ω in 5.0 mM [Fe(CN)6]3-/4- containing 0.1 M KCl. More importantly, the FeSe2/SPCE exhibited superior catalytic performance compared to the bare SPCE for FLD sensing based on the electrochemical response in terms of a peak potential of -0.44 V (vs Ag/AgCl (sat. KCl)) and cathodic response current of -22.8 μA. Operating at optimal conditions, the FeSe2-modified electrode showed wide linearity from 0.01 to 252.2 μM with a limit of detection of 0.002 μM and sensitivity of 1.15 μA μM-1 cm-2. The analytical performance of the FeSe2-based platform is significantly higher than many previously reported FLD electrochemical sensors. Furthermore, the FeSe2/SPCE also has a promising platform for FLD detection with high sensitivity, good selectivity, excellent stability, and robust reproducibility. Thus, the finding above shows that the FeSe2/SPCE is a highly suitable candidate for the electrochemical determination of glucose levels for real-time applications such as in human urine and river water samples.

A Disposable Screen Printed Electrodes with Hexagonal Ni(OH)2 Nanoplates Embedded Chitosan Layer for the Detection of Depression Biomarker.

Serotonin (5-hydroxytryptamine (5-HT)) is one of the important neurotransmitters which is released from the endocrine system. An abnormal level of this biomarker leads to several neurological diseases. The accurate assessment of serotonin is the utmost option to start treatment in the early stages of the disease. The current work is focused on the development of a disposable, screen-printed electrochemical sensor for the depression biomarker, serotonin in the physiological pH medium (pH 7.4) with the aid of a hexagonal, Ni(OH)2-nanoplate (NH-HNP)-embedded chitosan (Chit) and modified, screen-printed carbon electrode (SPCE). Initially, hexagonal nanoplates of Ni(OH)2 were synthesized by an eco-friendly and simple hydrothermal method. The prepared materials were well characterized by advanced analytical techniques to examine the physicochemical properties of the synthesized Ni(OH)2 hexagonal nanoplates. From the cyclic voltametric (CV) analysis, it was found that the oxidative current response of 5-HT at a NH-HNP-modified SPCE has about fivefold higher current values than over bare SPCE. The scan rate studies of NH-HNP-Chit/SPCE electrodes revealed that the oxidation mechanism of 5-HT is controlled by the diffusion behavior of the analyte. Differential pulse voltammetric tests of the NH-HNP-Chit/SPCE electrode exhibited a linear response in the dynamic concentration range of 0.1 to 30 µM, with a detection limit of about 60 nM. The sensor response is very reproducible from electrode to electrode, and the deactivation or surface-fouling of the sensor was not observed within the several experimental measurements. The sensor exhibited excellent storage stability over a period of twenty days. Finally, the fabricated, disposable SPCE sensor has shown respectable activity for the detection of depression biomarker 5-HT from synthetic urine and saliva samples.

Fabrication of a bi-metallic metal organic framework nanocomposite for selective and sensitive detection of triclosan.

Transition metal-ion based nanocomposites are widely used owing to their ease of synthesis and cost-effectiveness in the sensor development. In this study, we have synthesized bi-metallic (iron and zinc) metal organic framework (MOF) nanorods-nanoparticles (denoted as Fe2Zn-MIL-88B) with a well-defined structure and characterized them. The bimetallic material nanocomposite (Fe2Zn-MIL-88B, nafion (Nf), and multiwalled carbon nanotube (MWCNT)) was fabricated on the electrode (glassy carbon electrode (GCE) or screen printed carbon electrode (SPCE)) surface within 10 min at room temperature. The Fe2Zn-MIL-88B/Nf/MWCNT@GCE showed an excellent electron transfer mechanism compared to a bare GCE and bare SPCE. The Fe2Zn-MIL-88B based nanocomposite electrode triggers the oxidation of the environmental carcinogenic molecule triclosan (TCS). Under optimized conditions, the sensor has a limit of detection of 0.31 nM and high selectivity to TCS in the presence of other interfering agents. The sensor has a good day-to-day TCS detection reproducibility. Fe2Zn-MIL-88B was stable even after 11 months of synthesis and detected TCS with similar sensitivity. The fabrication of the Fe2Zn-MIL-88B/Nf/MWCNT nanocomposite was successfully translated from the GCE to SPCE. TCS was detected in human plasma and commercial products such as soaps, skin care products, shampoos, and tooth pastes.

Gold Nanospikes Formation on Screen-Printed Carbon Electrode through Electrodeposition Method for Non-Enzymatic Electrochemical Sensor

In this study, we reported the construction of Gold Nanospike (AuNS) structures on the surface of screen-printed carbon electrode (SPCE) used for non-enzymatic electrochemical detection. This modification was prepared with a one-step electrodeposition method by controlling the electrodeposition parameters, such as applied potential and deposition time, via Constant Potential Amperometry (CPA). Those parameters and precursor solution concentration were varied to investigate the optimum electrodeposition configuration. The results confirmed that AuNS were homogenously deposited and well-dispersed on the working electrode surface of SPCE. The AuNS-modified SPCE was implemented as a non-enzymatic sensor toward dopamine and could enhance the electrocatalytic ability compared with the bare SPCE. Further examination shows that the sensing performance of the AuNS-modified SPCE produced an increase in electrochemical surface area (ECSA) at 17.25 times higher than the bare electrode, a sensitivity of 0.056 µA mM−1 cm−2 with a wide linear range of 0.2–50 µM and a detection limit of 0.33 µM. In addition, AuNS-modified SPCE can selectively detect dopamine among other interfering analytes such as ascorbic acid, urea, and uric acid, which commonly coexist in the body fluid. This work demonstrated that AuNS-modified SPCE is a prospective sensing platform for non-enzymatic dopamine detection.

Fabrication and Characterization of Clinacanthus nutans Mediated Reduced Graphene Oxide Using a Green Approach

The reduction of graphene oxide (rGO) utilizing green methods such as plants has attracted much attention due to its productivity, eco—friendly features, and cost effectiveness. In the present study, the reflux method was employed to synthesize Clinacanthus nutans (C. nutans) leaf extract mediated rGO using a simple approach. The synthesized rGO was characterized using various spectroscopic and microscopic techniques. The UV-Vis spectrum demonstrated the absorption peak of rGO (270 nm) at distinct locations, while the FTIR analysis demonstrated that the amount of oxygen group in rGO was reduced. The Raman analysis confirms the reduction of GO by a slight increase in the D—band to G—band intensity ratio. The XRD spectra demonstrated that rGO was successfully produced based on the illustrated 2Ɵ angles at a peak of 22.12° with d-spacing of 0.40 nm. FESEM clearly reveals the morphology of rGO that shows crumpled thin sheets, a rougher surface, and a wave—shaped corrugated structure. The reduction of GO was analyzed in the removal of the hydroxyl group and amorphotization of sp2 carbon structures. The C/O ratio in rGO was higher than GO which indicates the small amount of oxygen-containing functional groups were still presented in the reduced graphene oxide. Furthermore, the cyclic voltammetry behavior of a modified screen—printed carbon electrode (SPCE) was measured. The redox reactivity of rGO—SPCE has been affirmed and compared with GO—SPCE and bare—SPCE. The toxicity using A. salina cysts demonstrated that rGO is less toxic compared to GO. The analysis adequately supports the synthesis of rGO and the effective removal of oxygen-containing functional groups from GO. The findings herein illustrate that C. nutans mediates the synthesis of rGO and is a promising eco-friendly substitute to conventional carbon-based fabrication.

Electrochemical and sensing properties of AuNps-2D-MoS2/SPCE for folic acid determination

A simple and sensitive electrochemical sensor was developed for the detection of folic acid (FA) based on gold nanoparticles (AuNPs) dispersed on exfoliated MoS2 (2D-MoS2) nanosheets by a simple impregnation method. The prepared 2D-MoS2 and AuNPs-MoS2 samples were characterized by scanning electron microscopy (SEM-EDX), UV–vis, and Raman spectroscopy. Screen-printed carbon electrodes (SPCE) were modified by the 2D-MoS2 and AuNPs-MoS2 nanosheets and their electrochemical characteristics were investigated by means of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques and tested in the electroanalytical determination of folic acid (FA). The modified 2D-MoS2/SPCE was found to promote the FA electrooxidation process compared to bare SPCE. Instead, with the AuNPs-MoS2/SPCE sensor a different sensing mechanism, based on the inhibition of the Au NPs redox peaks current, has been found to be more effective. This behavior was due to the strong binding of FA on AuNPs, as probed by in situ ATR-FTIR and SERS measurements. The decrease of the anodic peak current of Au NPs with the concentration of FA provided an indirect signal which has been used here for detecting FA.

Three-dimensional manganese cobaltate: a highly conductive electrocatalyst for paraoxon-ethyl detection.

The synthesis of manganese cobaltate (MnCo2O4) with the hybrid three-dimensional architecture has beendeveloped as an electrocatalyst for the electrochemical sensing of paraoxon-ethyl (PEL). The detailed physicochemical and structural characterization of MnCo2O4 is meticulously examined. The MnCo2O4-modified screen-printed carbon electrode (SPCE) exhibits good electrocatalytic activity for the reduction of PEL compared with the bare SPCE due to numerous unique properties. By profiting from these advantages, the proposed MnCo2O4/SPCE shows superior sensing performance toward the determination of PEL, including low cathodic peak potential (- 0.64V), wide detection range (0.015-435µM), low limit of detection (0.002µM), high detection sensitivity (2.30 µA µM-1cm-2), excellent selectivity, and good reproducibility. Notably, the electrochemical performance of the MnCo2O4-based electrocatalyst is superior to those previously reported in the literatures. The practical application of the MnCo2O4/SPCE is effectively assessed in the analysis offood and water samples with satisfied recoveries of 96.00-99.35%. The superior performance of the proposed MnCo2O4 electrocatalyst holds considerable potential for future development of electrochemical sensing platforms.

Enhanced electrochemical detection of iodide at a reduced graphene oxide–modified carbon electrode in iodized salts

In this study, enhancement of electrochemical performance of electrochemically reduced graphene oxide (ERGO) on a screen-printed carbon electrode (SPCE) (ERGO/SPCE) coupled with ion-pairing (cetyltrimethylammonium bromide, CTAB) for the determination of iodide in table salt has been described. The electrode modification of ERGO/SPCE was conducted using cyclic voltammetric (CV) scanning in the potential range of 1.3–0.4 V for 50 cycles after the drop-casting of graphene oxide (GO) suspension on the SPCE. It was found that the electro-active surface area of ERGO/SPCE was increased by 1.5-fold compared to the bare SPCE. ERGO/SPCE sensor displays linearity towards iodide in the concentration range from 0.020 to 1.0 mg/L (sensitivity = 5.40 µA(mg/L)−1, R2 = 0.9906) with the limit of detection (LOD) and limit of quantitation (LOQ) of 0.070 mg/L and 0.21 mg/L, respectively. The comparison between polarography and ERGO/SPCE sensor was in good agreement.

Screen-printed carbon electrode modified with de-bundled single-walled carbon nanotubes for voltammetric determination of norepinephrine in ex vivo rat tissue

A voltammetric sensor for norepinephrine (NE) detection was developed by modifying a disposable screen-printed carbon electrode (SPCE) with de-bundled single-walled carbon nanotubes (D-SWCNTs). The de-bundling was carried out using a newly synthesized polymeric dispersant, a co-polymer of polystyrene sulfonate and methacrylate of lipoic acid. The D-SWCNTs/SPCE showed better sensitivity towards NE compared to the bare SPCE and that modified with bundled SWCNTs. The sensor was optimized for detecting NE by differential pulse voltammetry (DPV) in terms of the D-SWCNTs concentration, DPV parameters, and solution pH. Under the optimum conditions, the sensor exhibited a dynamic linear range of 100 nM–2.0 µM NE, and the detection limit was 62.0 nM (S/N = 3). Additionally, the effects of possible interferents were investigated. The relative standard deviation for five successive measurements of 2.0 µM NE was 7.6%, and approximately 75.8% of the sensor activity was retained after four weeks of storage. The practical potential of this sensor was demonstrated by quantifying NE in ex vivo rat tissue samples.

Study of Different Carbonaceous Materials as Modifiers of Screen‐printed Carbon Electrodes for the Triazid as Potential Antiviral Drug

AbstractIn this work a comparative study of Screen‐Printed Carbon Electrodes (SPCE) – bare and modified by drop casting with carbonaceous nanomaterials (CNMs) as Multi Walled Carbon Nanotubes (MWCNT), Carbon Black and Functionalized Carbon Black for voltammetric determination of 5‐methyl‐6‐nitro‐7‐oxo‐4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidinide l‐arginine monohydrate (Triazid) as a potential drug with a broad spectrum of antiviral activity is reported. Bare SPCE and CNMs modified SPCE (SPCE/CNMs) have been characterized morphologically by SEM and electrochemically by cyclic voltammetry/electrochemical impedance spectroscopy with [Fe(CN)6]4−/3− as redox probe. Significant improvement of electrochemical performances is achieved with SPCE/CNMs compared with the bare SPCE. Among SPCE/CNMs studied SPCE modified with MWCNT (SPCE/CNT) is characterized by the best combination of electrochemical properties and electroanalytical performance towards TD. The linear dynamic range is 25–200 mg L−1 (R2=0.9975) with the limit of detection – 2.8 mg L−1 Triazid using SPCE/CNT and Square‐Wave Voltammetry technique. The developed sensor was successfully used for Triazid determination in the Pharmaceutical Substance “TRIAZID”. The results achieved with SPCE/CNMs after chemical binding of dissolved oxygen in 0.04 M Britton‐Robinson buffer+0.04 M Na2SO3 (pH 7.2±0.2) are very useful for further development of cost‐effective and time‐consuming pharmaceutical routine assay.

Nanochannel Array on Electrochemically Polarized Screen Printed Carbon Electrode for Rapid and Sensitive Electrochemical Determination of Clozapine in Human Whole Blood.

Rapid and highly sensitive determination of clozapine (CLZ), a psychotropic drug for the treatment of refractory schizophrenia, in patients is of great significance to reduce the risk of disease recurrence. However, direct electroanalysis of CLZ in human whole blood remains a great challenge owing to the remarkable fouling that occurs in a complex matrix. In this work, a miniaturized, integrated, disposable electrochemical sensing platform based on the integration of nanochannel arrays on the surface of screen-printed carbon electrodes (SPCE) is demonstrated. The device achieves high determination sensitivity while also offering the electrode anti-fouling and anti-interference capabilities. To enhance the electrochemical performance of SPCE, simple electrochemical polarization including anodic oxidation and cathodic reduction is applied to pretreat SPCE. The electrochemically polarized SPCE (p-SPCE) exhibits an enhanced electrochemical peak signal toward CLZ compared with bare SPCE. An electrochemically assisted self-assembly method (EASA) is utilized to conveniently electrodeposit a vertically ordered mesoporous silica nanomembrane film (VMSF) on the p-SPCE, which could further enrich CLZ through electrostatic interactions. Owing to the dual signal amplification based on the p-SPCE and VMSF nanochannels, the developed VMSF/SPCE sensor enables determination of CLZ in the range from 50 nM to 20 μM with a low limit of detection (LOD) of 28 nM (S/N = 3). Combined with the excellent anti-fouling and anti-interference abilities of VMSF, direct and sensitive determination of CLZ in human blood is also achieved.

Screen Printed Carbon Electrodes Modified with 3D Nanostructured Materials for Bioanalysis

AbstractHere, the modification of screen‐printed carbon electrodes (SPCEs) with 3D nanostructured multi‐walled carbon nanotube‐sponge (MWCNT‐Spng) and graphene foam along with their impact on analytical performance was reported. The bare and modified SPCE electrodes were imaged and characterized using scanning electron microscopy, energy dispersive and electrochemical impedance spectroscopy. The modified electrodes were tested for electrochemical detection of dopamine (DA) and a significant improvement was observed in terms of both limit of detection (LOD) and sensitivity as compared to bare SPCE. MWCNT‐Spng‐AuNPs/SPCE demonstrated the highest analytical performance for DA. It was also tested for enzyme‐free glucose detection, in which case it demonstrated an LOD of 4.96 μM and a sensitivity of 526 μA/mM⋅cm2, along with a good selectivity for glucose.

Electrochemical Sensor Nanoarchitectonics for Sensitive Detection of Uric Acid in Human Whole Blood Based on Screen-Printed Carbon Electrode Equipped with Vertically-Ordered Mesoporous Silica-Nanochannel Film.

Screen-printed carbon electrodes (SPCEs) bear great potential in the detection of biomarker in clinical samples with low sample consumption. However, modification of electrode surfaces to improve the anti-interference ability and sensitivity is highly desirable for direct electroanalysis of whole blood samples. Here, a reliable and miniaturized electrochemical sensor is demonstrated based on SPCE equipped with vertically-ordered mesoporous silica-nanochannel film (VMSF). To achieve stable binding of VMSF and improve the electrocatalytic performance, electrochemically reduced graphene oxide (ErGO) is applied as a conductive adhesion layer, that is in situ reduced from GO nanosheets during fast growth (less than 10 s) of amino groups modified VMSF (NH2-VMSF) using electrochemically assisted self-assembly (EASA). In comparison with bare SPCE, NH2-VMSF/ErGO/SPCE exhibits decreased oxidation potential of uric acid (UA) by 147 mV owing to significant electrocatalytic ability of ErGO. The dual signal amplification based on electrocatalysis of ErGO and enrichment of nanochannels leads to enhanced peak current by 3.9 times. Thus, the developed NH2-VMSF/ErGO/SPCE sensor enables sensitive detection of UA in the range from 0.5 μM to 180 μM with a low limit of detection (LOD, 129 nM, S/N = 3). Owing to good anti-fouling ability and high selectivity of the sensor, direct and rapid detection of UA in human whole blood is realized with very low sample consumption (50 μL).