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The research paper focused on fabrication of an electrochemical sensor to sensing and monitoring of vanillin in aqueous solution. In this regard, NiO/nitrogen doped carbon quantum dots (NiO-NCQD) nanocomposite was synthesized as a highly conductive catalyst and used to modification of carbon paste electrode (CPE) and fabricated a sensitive voltammetric sensor. The oxidation signal of vanillin showed a catalytic activity at surface of NiO-NCQD/CPE compare to CPE in aqueous solution at pH = 7.0. The NiO-NCQD/CPE showed a linear range 0.01–280 µM, with a limit of detection (LOD) 5.0 nM, respectively. The NiO-NCQD/CPE was test to monitoring of vanillin in different food products and results compare with HPLC method. Results confirmed accuracy and precision suggested method to sensing of vanillin in food products. [ABSTRACT FROM AUTHOR]

Generally, our ecosystem is continuously contaminated as a result of anthropogenic activities that form the basis of our comfort in our routine life. Thus, most scientists are engaged in the development of new technologies that can be used in environmental remediation. Herein, highly calcined binary metal oxide (Er2O3@NiO) semiconductor nanocomposite (NC) was synthesized using a classical wet chemical process with the intention to both detect and degrade the toxic chemicals in an aqueous medium using a novel electrochemical current–potential (I–V) approach for the first time. Optical, morphological, and structural properties of the newly synthesized semiconductor NC were also studied in detail using FT-IR, UV/Vis., FESEM-EDS, XPS, BET, EIS, and XRD techniques. Then, a modified glassy carbon electrode (GCE) based on the newly synthesized semiconductor nanocomposite (Er2O3@NiO-NC/Nafion/GCE) as a selective electrochemical sensor was fabricated with the help of 5% ethanolic-Nafion as the conducting polymer binder in order to both detect and electro-hydrolyze toxic chemicals in an aqueous medium. Comparative study showed that this newly developed Er2O3@NiO-NC/Nafion/GCE was found to be very selective against m-tolyl hydrazine (m-Tolyl HDZN) and to have good affinity in the presence of other interfering toxic chemicals. Analytical parameters were also studied in this approach to optimize the newly designed Er2O3@NiO-NC/Nafion/GCE as an efficient and selective m-Tolyl HDZN sensor. Its limit of detection (LOD) at an SNR of 3 was calculated as 0.066 pM over the linear dynamic range (LDR) of our target analyte concentration (0.1 pM–0.1 mM). The limit of quantification (LOQ) and sensitivity were also calculated as 0.22 pM and 14.50 µAµM−1cm−2, respectively. m-Tolyl HDZN is among the toxic chemicals in our ecosystem that have lethal effects in living beings. Therefore, this newly designed electrochemical sensor based on semiconductor nanostructure material offers, for the first time, a cost-effective technique, in addition to long-term stability, that can be used as an alternative for efficiently probing other toxic chemicals in real samples. [ABSTRACT FROM AUTHOR]

In order to prepare fiber-type nanohybrid composites for electrochemical and antimicrobial applications, polypyrrole was combined with carboxymethylcellulose and multiwalled carbon nanotubes (PPy/CMC/MWCNTS). These composite materials were synthesized using ultrasonication and in situ polymerization. By using analytical methods, the structure and morphology of the synthesized nanohybrid composite material were confirmed. Slurry of fiber-type PPY/CMC/MWCNT composites synthesized in ethanol was deposited as a thin-uniform layer with conductive nafion (5% ethanolic solution of nafion) binder. Based on electrochemical measurements in a phosphate buffer medium, Sb3+ ions have linear responses between 0.1 nM and 0.01 mM, which is known as linear dynamic range (LDR). A sensor's sensitivity (22.4304 µAµM−1cm−2) is calculated using the LDR slope by considering the GCE surface area (0.0316 cm2). A signal-to-noise ratio of 3 is used to estimate the lower limit of detection which is equal to 96.82 ± 4.84 pM. Moreover, the antibacterial activity of the obtained polypyrrole/carboxymethylcellulose/MWCNT composite has also been evaluated "against Gram-positive bacteria B. subtilis along with S. aureus, as well as Gram-negative bacteria, P. aeruginosa along with Escherichia coli by utilizing" autoclave of agar media. In electrochemical analysis, the proposed Sb3+ cationic sensor exhibits appreciable reproducibility, response time, stability, and outstanding outcome in analysis of real samples. In the field of metal ion sensor, this reliable method might be prospective in the recent future. [ABSTRACT FROM AUTHOR]

A promising electrochemical strategy for assay of N6-methyladenosine (m6A)/N6-methyladenine (6mA) in RNA/DNA is proposed. The key of this strategy is the end-labeling of nucleic acid, which makes it possible to detect methylation level in unknown sequence. Firstly, the end of m6A-RNA or 6mA-DNA was labeled with sulfhydryl group through T4 polynucleotide kinase (T4 PNK) and then directly assembled on a gold nanoparticle–modified glassy carbon electrode (AuNPs/GCE). Secondly, methylation sites in RNA/DNA were specifically recognized by anti-m6A-antibody, and then, horseradish peroxidase–labeled goat anti-rabbit IgG (HRP-IgG) was further conjugated on the antibody. Thirdly, HRP-IgG catalyzed the hydroquinone oxidation reaction to generate amplified current signal which correlates with the amount of m6A/6mA in nucleic acid. This method showed a wide linear range from 0.0001 to 10 nM for m6A-RNA, 0.001 to 100 nM for 6mA-dsDNA, and 0.0001 to 10 nM for 6mA-ssDNA. The method was successfully applied to detection of m6A/6mA in RNA/DNA from HeLa cells and E. coli cells and validation of the decrease of m6A-RNA in HeLa cells after treatment with FTO protein. [ABSTRACT FROM AUTHOR]

As emerging pollutants, antibiotics are ubiquitous in the environment and pose a threat to human health, giving rise to an urgent need to assess their biological toxicity. In the present study, a cell electrochemical method based on the bromocresol violet/carbon nanotubes/glassy carbon electrode (BCP/MWCNTs/GCE) was established to evaluate the cytotoxicities of sulfamethoxazole (SMZ), ciprofloxacin (CIP), and tetracycline (TC). BCP/MWCNTs/GCE has advantages due to its excellent electrocatalytic activity for the oxidation of electroactive species of the Ctenopharyngodon idellus kidney (CIK) cells. The half-maximal inhibitory concentration (IC50) values of SMZ, CIP, and TC obtained by the electrochemical method were 831.51 μM, 354.98 μM, and 184.51 μM, which were lower than those of the traditional methyl-thiazolyl-tetrazolium (MTT) assay (907.47 μM, 414.87 μM, and 208.11 μM). These results indicate the higher sensitivity of the electrochemical method. This study provided a sensitive tool for the cytotoxicity evaluation of antibiotics in the environmental toxicology field. [ABSTRACT FROM AUTHOR]

The synthesized MgTi2O4⋅TiO2⋅Zn2TiO4 nanomaterial was characterized by XRD (X‐Ray diffraction), SEM (Scanning electron microscopy), EDS (Energy dispersive x‐ray spectroscopy), FTIR (Fourier transform infrared spectroscopy) and PL (Photoluminescence) study. Particles size of MgTi2O4⋅TiO2⋅Zn2TiO4 nanomaterial was found to be 37.3 nm. PL and PLE (Photoluminescence excitation) spectra are showed several peaks including one red PL at 723 nm, when excited at 320 nm. Nanomaterial was subject to electrochemical sensor study. Thin layer of synthesized MgTi2O4⋅TiO2⋅Zn2TiO4 nanomaterials was fabricated onto the glassy carbon electrode (GCE) with conducting binder to result the working electrode of 4‐nitrophenylhydrazine (4‐NPHyd) sensor, which was applied successively to selectively detect the 4‐NPHyd in aqueous phase. The 4‐NPHyd chemical sensor exhibited high sensitivity with lower detection limit, long‐term stability in chemical environment and improved electrochemical responses during sensing performance. The linearity of calibration plot is obtained over the large linear dynamic range (LDR) from 0.1 nM to 0.1 mM of 4‐NPHyd. The sensitivity calculated from the slop of calibration plot (ratio of current to concentration of 4‐NPHyd) is 42.7215 μAmM−1cm−2 with detection limit (DL) of 0.02±0.001 nM at signal to noise ratio of 3(S/N). Therefore, the chemical sensor based on MgTi2O4⋅TiO2⋅Zn2TiO4 nanomaterials may be a promising highly sensitive sensor in electrochemical method for the effective detection of hazardous and carcinogenic chemicals in medical as well as biological sectors. [ABSTRACT FROM AUTHOR]

The well-dispersed CuO doped poly(methyl methacrylate) (CuO–PMMA) nanocomposites (NCs) with a successful loading of SWCNT as carbon nanofillers with different percentages (2%, 5%, and 10%) were fabricated effectively via the ex-situ polymerization technique. XRD, SEM–EDX, SEM-Map, TEM, AFM, Raman, and FTIR were carried out to confirm the formation of CuO–PMMA NCs, as well as the formation of CuO–PMMA–SWCNT NCs on the surface of CuO–PMMA sheet nanocomposite. The morphology of both CuO nanoparticles and SWCNT on the PMMA sheet, as well as agglomeration, concentration, roughness profiles, and size distribution, were considered during the experiments. BET surface area was carried out to determine the effect of various percentages of SWCNT loading on CuO–PMMA NC on the BET surface area. Furthermore, thermogravimetric analysis was conducted to evaluate the thermal behavior. Interestingly, the thermal stability of the NCs was inferred to significantly enhance with a proper amount of SWCNTs. EDX and elemental mapping of Cu, C, and O confirmed the presence of SWCNTs and CuO on the PMMA polymer matrix. In this approach, various loadings of SWCNT were performed into the CuO–PMMA–SWCNT NCs for the selective detection of metal ions using the electrochemical method. It exhibited the best performance in the detection of particular Mn2+ cation to 2% of SWCNT loading into NCs. The Mn2+ cationic sensor analytical response was investigated by CuO–PMMA–SWCNT (2%) NCs with glassy carbon electrode (GCE) coated uniform thin film using conductive nafion (5% nafion) binder. The sensor showed linear electrochemical responses over the concentration range of 0.1 nM to 0.01 mM identified through the calibration curve, which is known as the linear dynamic range. The sensor analytical performance sensitivity (88.16 µA µM−1 cm−2) and detection limit (92.67 ± 4.63 pM) were calculated from the slope of the calibration curve. The proposed Mn2+ ion sensor based on CuO–PMMA–SWCNT (2%) NCs/binder/GCE was found satisfactory in terms of reproducibility, linear dynamic range detection limit, sensitivity, stability, and response time. In real environmental samples, it also showed substantial performances during detection. This methodology can be inferred safely as a unique approach to develop metal ion sensors using inorganic-carbon NCs on GCE. [ABSTRACT FROM AUTHOR]

• The TiO 2 -MXene/MWCNTs/PDA/GCE electrode was successfully prepared, and it has a low detection limit for xanthine, reaching 0.018 µmol·L−1. • The electrochemical method was used to study the effects of three different structures of OPAHs on purine metabolism in HFF-1 cells. • Electrochemical method was used for the first time for the toxicity evaluation of OPAHs, and it exhibited higher sensitivity than the MTT method. Oxygenated polycyclic aromatic hydrocarbons (OPAHs) present in the environment can enter the skin through direct contact and long-term exposure can increase the risk of skin inflammation, allergic reactions and skin cancer. In this study, a titanium dioxide-two-dimensional transition metal carbide/multi-walled carbon nanotubes/polydopamine/glassy carbon electrode (TiO 2 -MXene/MWCNTs/PDA/GCE) electrochemical biosensor was prepared to evaluate the cytotoxicity of OPAHs based on the changes in the content of xanthine/guanine (X/G) during cellular metabolism. The TiO 2 -MXene/MWCNTs/PDA/GCE exhibited excellent electrocatalytic activity and sensitivity. The surface morphology, structure and electrochemical properties of TiO 2 -MXene/MWCNTs/PDA composite material were characterized using scanning electron microscopy, X-ray diffraction and cyclic voltammetry. Human skin fibroblast cells (HFF-1) were used as model cells, and the cell viability was evaluated based on the electrochemical signal changes of X/G. When exposed to OPAHs for 30 h, the half-maximal inhibitory concentrations (IC 50) of 1,4-benzoquinone (1,4-BQ), 1,2-naphthoquinone (1,2-NQ), and 9,10-phenanthrenequinone (9,10-PQ) on HFF-1 cells were 291.88, 67.72, and 4.44 µmol·L−1, respectively, which were lower than the IC 50 values of 1075.51, 113.96, and 9.63 µmol·L−1 obtained using the traditional MTT assay, indicating higher sensitivity of the sensor. This study achieved sensitive detection of purines in HFF-1 cells, providing a technical method for evaluating the cytotoxicity of persistent organic pollutants OPAHs in the environment. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphene oxide/methylaniline (GO/MA) nanocomposites (NCs) were synthesized by an in situ inverse microemulsion polymerization method. The characterization of nanocomposites is done by scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) methods. In addition, an efficient chemical sensor probe was fabricated with flat glassy carbon electrode (GCE) by coating with thin layer of synthesized GO/MA NCs. Then the sensor was applied for the selective detection of lead (Pb+2) ion in an aqueous phase. The sensor performance such as sensitivity (20.56 µA mM−1 cm−2) was calculated from the slope of the calibration curve. The linear dynamic range (LDR: 0.1 nM–0.01 M) was calculated on the maximum linearity line from the calibration plot. The detection limit (DL: 50.0 ± 2.5 pM) was also calculated from the slope of the calibration plot by considering of 3 N/S (signal-to-noise ratio of 3). This novel electrochemical approach introduced a reliable and efficient route to detect the heavy metal ions as selective sensor for the safety of medical, biochemical and environmental fields in broad scales. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride/mixed graphene-carbon nanotube nanocomposites have been fabricated in the form of (PVC/MG-CNTsa-e) via simple dissolution method with the help of ultrasonic assistance. First, mixed G:CNTs ratio (50:50) wt by wt was prepared. Then, different loadings of that mixed G/CNTs ratio (2, 5, 10, 20, and 30 wt %) were added to the PVC polymer matrix. The fabricated PVC/MG-CNTsa-e nanocomposites were characterized by different techniques including: FT-IR, XRD, SEM, TEM and thermal analyses. The perception found in the FT-IR results of PVC nanocomposites confirm the introduction of mixed G/CNTs nanoparticles in the PVC polymer matrix. The mixed G/CNTs were stimulated in highly regular order in the PVC film and its crystallinity was significantly improved. The thermal property of pure PVC polymer matrix was noted to be highly improved by combining the mixed G/CNTs in the form of nanocomposites. CDT max for all the samples were nearly similar and appeared in the same range of 270–305℃. Here, a potential Ag+ ionic sensor has been fabricated based on the glassy carbon electrode coated by PVC/MG-CNT NCs to make a thin layer as working electrode probe. The slope of the calibration curve plotted as current versus the concentration of Ag+ ion was used to calculate the sensitivity (6.4241 µAµM−1cm−2) by considering the active surface area of the sensor probe. The current observation based on Ag+ ionic concentration is found to be linear over the linear dynamic range, where the detection limit (DL = 14.78 ± 0.74 pM) is measured by considering the signal to noise ratio at 3. Considering the application feature of Ag+ ion sensor, the proposed sensor was demonstrated to have good reproducibility and reliability for the sensor application through the determination of toxins in environmental and healthcare fields at broad scales. [ABSTRACT FROM AUTHOR]

Abstract The Tetradentate Schiff base was easily prepared from o -phenylenediamine and salicylaldehyde and used as a ligand for the detection of heavy metal ions in phosphate buffer medium by electrochemical approach. To fabricate the selective lead (Pb2+) ion sensor, a slurry of the synthesized 2,2′-(−(1,2-phenylenebis(azaneylylidene))bis(methaneylylidene))diphenol (TDL) ligand was deposited onto glassy carbon electrode (GCE) as uniform thin-layer. The calibration curve of the proposed Pb2+ ion sensor in form of a current vs. concentration plot is found to be linear over Pb2+ ion concentration range (0.1 nM ~ 0.01 mM). The sensitivity of the sensor is very high (8.84 μAμM−1 cm−2) and detection limit is as low as 98.02 ± 0.50 pM (Limit of quantification is 316.73 pM). The projected Pb2+ sensor with active TDL shows reliability, precise reproducibility and short response time (16.0 s.) during sensing performances. Above all, it was showed successive applicability to detect the real environmental samples. In the field sensor development, this methodology using TDL onto GCE might be ae efficient and reliable innovative technique for the detection of heavy metal ions by electrochemical methods. Graphical abstract Unlabelled Image Highlights • Tetradentate TDL Schiff-base was prepared by condensation method • TDL/Nafion/GCE Pb2+ sensor probe was fabricated • The highest sensitivity (~25.05 μAμM−1 cm−2) was achieved • The lowest LOD (~37.88 ± 1.89 pM) was found • Environmental and healthcare safety [ABSTRACT FROM AUTHOR]

Abstract Synthesis of carboxyl-functionalized MWCNT/poly(o -toluidine) nanowires (OH-MWCNT/POT NWs) was achieved through micro emulsion and in-situ oxidative polymerization methods. A mixture of dodecylbenzenesulfonic was used as microemulsion surfactant, while Na 2 S 2 O 8 in HCl was utilized as an active oxidant. The structure, morphology, thermal, and sensing properties of the OH-MWCNT/POT NWs were analyzed in details. Then, the OH-MWCNT/POT NWs was utilized to develop an efficient cationic sensor by electrochemical method. A cationic sensor based on NCs for selective Ce3+ ions was prepared by coating of glassy carbon electrode (GCE). A thin-layer of the prepared OH-MWCNT/POT NWs was made with the help of 5% nafion as a conducting binder. The obtained calibration curve was found to be linear over the linear dynamic range (LDR) of 0.1 nM–0.01 mM. The sensitivity (47.0411 μA·μM−1·cm−2) to the Ce3+ cation was estimated from the slope of the calibration curve. The detection limit (96.03 ± 4.80 pM) was also calculated from the calibration curve by considering the signal-to-noise ratio of 3. On a broad scale, this approach may introduce a highly efficient method for the detection of Ce3+ cations in toxic chemicals as well as environmental fields. Highlights • Poly(o -toluidine)/carboxyl-functionalized MWCNT nanowires were prepared. • High-sensitivity (47.0411 μA·μM−1·cm−2) towards Ce3+ sensor was achieved. • An ultra-low detection limit (96.03 ± 4.80 pM) was obtained by 3 N / S ratio. • Real environmental samples were successfully validated. • Potential applications for health-care and environmental safety [ABSTRACT FROM AUTHOR]

Abstract In this study, conducting polyaniline (PAni) and silicon dioxide (SiO 2) nanocomposites (NCs) were synthesized for chemical sensing applications by microwave assisted reaction technique. Facile synthesis and characterization of the PAni-SiO 2 nanocomposites were investigated in details and discussed in this report. For the potential application, 1,4-dioxane chemical sensor was fabricated with the PAni-SiO 2 nanocomposites deposited onto glassy carbon electrode (GCE). A very thin uniform film was deposited onto GCE with nanocomposite by using conducting 5% nafion binder at room conditions. To evaluate the sensor analytical performances, a calibration plot such as current versus concentration of 1,4-dioxane was drawn and calculated the analytical parameters from the slope of calibration curve. Results are found as sensitivity (0.5934 µAµmol-1 L−2 cm−2), detection limit (16.0 ± 0.8 pmol L−1), and quantification limit (LOQ; 53.3 ± 1.5 pmol L−1) in this observation. Considering the linear region in calibration plot, the linear dynamic range of 1,4-dioxane chemical sensor was found (0.12 nmol L−1 ∼ 1.2 mmol L−1). Besides this, the proposed 1,4-dioxane chemical sensor was exhibited good reproducibility, long-term stability, high accuracy in detecting of 1,4-dioxane in real environmental samples. This research is to develop of a selective and an efficient electrochemical sensor. It might be a simple and easy way by applying electrochemical method to ensure the safe and sustainable green environment. Graphical abstract fx1 Highlights • PAni-SiO 2 nanocomposites prepared by microwave method. • Highly sensitive 1,4-dioxane chemi-sensor by reliable electrochemical method. • Chemi-sensor exhibits the lower detection limit within short response time. • Practically analyzed the real environmental samples. • Effective chemi-sensor for health care and environmental fields. [ABSTRACT FROM AUTHOR]

Integration of LFO/rGO nanocomposite for the electrochemical detection of MTZ in human urine and milk samples. [Display omitted] • LFO/rGO nanocomposite was synthesized through a facile sonochemical approach. • LFO/rGO/GCE had excellent electrocatalytic activity for MTZ. • The modified sensor exhibited a wide linear range and a low limit of detection. • The sensor showed outstanding performance in the analysis of urine and milk samples. Metronidazole (MTZ) is a nitroimidazole antibiotic commonly used to treat bacterial infections, but its residues in food products may pose teratogenic, mutagenic, and carcinogenic risks to human health. Hence, monitoring MTZ in food and human samples is essential. In this study, we developed a glassy carbon electrode (GCE) modified with lanthanum ferrite (LFO) integrated with reduced graphene oxide (rGO) nanocomposite for the electrochemical detection of MTZ. The engineered nanocomposite was prepared by the sonochemical treatment and then systematically characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The modified LFO/rGO/GCE exhibits excellent electrochemical performance, which is mainly owing to the high surface areas, conductivity, and synergistic effects of LFO and rGO. Using the DPV method, the LFO/rGO/GCE sensor showed a wide linear range of 0.2–1221 µM and a low LOD of 0.048 µM for MTZ detection. The modified sensor selectivity was confirmed with biological species and metal compounds. In addition, the developed sensor demonstrated good stability, reproducibility, and repeatability toward MTZ. Satisfactory recoveries were obtained for MTZ detection in human urine and milk samples using the fabricated LFO/rGO/GCE sensor. [ABSTRACT FROM AUTHOR]

The contamination of arsenic (As3+) cation in drinking water is one of the most well‐known sources for human arsenic poison. Due to its high toxicity to human, there is a need to develop an efficient and low‐cost method to detect it in aquatic environment. A sensor of nitrated polyethersulfone (PES‐NO2) doped with ZnYNiO nanocomposites was successfully fabricated. PES‐NO2 was synthesized in this study using H2SO4: HNO3 while ZnYNiO nanoparticles were fabricated using wet‐chemical technique under low temperature and basic condition. The results of Fourier transform infrared spectroscopy (FT‐IR) and X‐ray diffraction (XRD) analysis did confirm the interactions between the doped nanoparticles and nitro functions grafted on PES backbone. The developed polymeric nanocomposite (PES‐NO2‐ZnYNiO) was then used as a superb coating sensor for As3+. The working electrode of desire heavy metal ion sensor was fabricated by glassy carbon electrode (GCE) coated with PES‐NO2‐ZnYNiO nanocomposites as layer of thin film. To estimate the cationic sensor performances, a calibration curve obtained from current versus electrolyte (selective As3+ ion) concentration relation was plotted. The linearity of calibration curve is found over the linear dynamic range (LDR) of 0.1 nM~0.1 mM. The slope of calibration curve is used to measure the sensitivity and detection limit (DL) of As3+ cation sensor, and these are 9.8101 μA μM−1 cm−2 and 96.77 ± 4.84 pM, respectively. Therefore, the As3+ ion sensor is found as selective with good sensitivity, reproducible with high accuracy, validated in real environmental samples, long‐term stability in aqueous medium, and highly active with short response time. [ABSTRACT FROM AUTHOR]

A new category of thermally stable hybrid polyarylidene(azomethine-ether)s and copolyarylidene(azomethine-ether)s (PAAP) based on diarylidenecycloalkanones has been synthesized using solution polycondensation method. For potential cationic sensor development, a thin layer of PAAP onto a flat glassy carbon electrode (GCE, surface area: 0.0316 cm2) was prepared with conducting nafion (5%) coating agent to fabricate a sensitive and selective arsenic (III) [As3+] ion in short response time in neutral buffer system. The fabricated cationic sensor was measured the analytical performances such as higher sensitivity, linear dynamic range, detection limit, reproducibility, and long-term stability towards As3+ ions. The sensitivity and detection limit were calculated as 2.714 μAμM−1cm−2 and 6.8 ± 0.1 nM (SNR of 3; 3N/S) respectively from the calibration curve. This novel approach can be initiated a well-organized route of an efficient development of heavy selective arsenic sensor for hazardous pollutants in biological, environmental, and health care fields. Real sample analysis for various environmental sample was performed with PAAP-modified-GCE. [ABSTRACT FROM AUTHOR]

Abstract A three-dimensional graphene-based ratiometric signal amplification aptasensor for highly sensitive and selective detection of mucin1 (MUC1) by electrochemical method has been developed. Au-reduced graphene oxide (Au-RGO) composite, which was synthesized through hydrothermal reaction and freeze-drying treatment, was used as substrate for fabricating the sensor interface on glassy carbon electrode (GCE). The application of Au-RGO is beneficial for improving electrochemical performance and immobilizing aptamer. Ferrocene labeled aptamer (Fc-Apt), grafting on Au-RGO composite, worked for specific recognition of MUC1 and as internal reference to improve the detection accuracy. Au nanoparticle modified with methyl blue labeled aptamer (MB-Apt@Au) was adopted to combine with MUC1 that captured on the electrode surface to amplify the electrical signal. Under optimal experimental conditions, this sensor was applied to detect a series concentration of MUC1 solution by alternating current voltammetry method. The aptasensor shows satisfactory detection results with a wide linear range of 1 pM to 1 µM, a low detection limit of 0.25 pM and good specificity. The good performance of the prepared electrochemical aptasensor implies that this method has potential for MUC1 detection, and it would be promising for early screening and diagnosis of cancer diseases. The proposed method also lays an important foundation for preparing ratiometric signal amplification aptasensor for other biomarkers detection. Highlights • A three-dimensional graphene-based ratiometric signal amplification aptasensor for MUC1 detection. • Three-dimensional Au-RGO composite was used as backing material for sensing interface construction to enlarge GCE surface and enhance its conductivity. • The ferrocene labeled MUC1 aptamer worked for specific recognition of MUC1 molecules and as internal reference, which was beneficial for improving the detection performance. • Au nanoparticle modified with methyl blue labeled aptamer was adopted to combine with MUC1 to amplify the detection signal. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A linear Schiff base (BZNA) as Cd2+ sensor synthesized and fully characterized. • Highly sensitive Cd2+ sensor by reliable I-V method. • Cd2+ sensor exhibits the lower detection limit within short response time. • Practically analyzed the real environmental samples. • Effective cationic sensor for healthcare and environmental fields. Abstract A new electrochemical sensor for the selective detection of Cd2+ ion based on Schiff base, 1,1′-(biphenyl-4,4′-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene) dinaphthalen-2-ol (BZNA) having from both moieties 2-hydroxy-1-iminomethylnaphthalene and benzidine core is presented. BZNA was synthesized by condensation reaction and then fully characterized. A thin film of BZNA was fabricated onto Nafion/Glassy carbon electrode (GCE) with 5.0% ethanolic solution of Nafion as the conducting coating agent. A slurry of BZNA was used to coat the GCE (GCE; 0.0316 cm2) as a thin layer for the selective detection of Cd2+ ion in an aqueous solution. A linear calibration curve that has a linear dynamic range (LDR) from 0.1 nM to ∼0.1 mM is obtained. From the slope of the plot, the calculated sensitivity, limit of detection (LOD), and limit of quantification (LOQ) of Cd2+ ion were found to be 2.93 µA µM−1 cm−2, 32.0 ± 1.62 pM, and 106.67 pM respectively. This novel approach might pave the way for the development of heavy metal ion detection process in the fields of environmental and healthcare. [ABSTRACT FROM AUTHOR]

Early detection of Parkinson's disease (PD), as a dangerous neurodegenerative disease, is a key factor in the therapy or prevention of further development of this disease. We developed an electrochemical nanobiosensor for early detection of PD based on the quantification of circulating biomarker, miR-195. Exfoliated graphene oxide (EGO) and gold nanowires (GNWs) were used to modify the surface of screen-printed carbon electrode. A single-strand thiolated probe was designed for specific hybridization with target miRNA (miR-195), and doxorubicin was used as an electrochemical indicator for differential pulse voltammetry measurements. The results of scanning electron microscope imaging and cyclic voltammetry experiments confirmed the accuracy of the working electrode modification steps. The results of analytical performance nanobiosensor showed a high sensitivity of the biosensing with 2.9 femtomolar detection limit and dynamic range of 10.0–900.0 femtomolar. In addition, good selectivity for target miRNA over non-specific oligonucleotides (one and three base replacement in target miRNA, and non-complementary) was achieved. The results of real human serum analysis did not show any interference in the function of the biosensor. Based on the results, the miR-195 electrochemical nanobiosensor could be suggested for clinicians in the medical diagnosis of PD. [ABSTRACT FROM AUTHOR]

Bentazone (BZ) is selective contact-past herbicide with suspected reproductive toxicity potential for human due to possible contamination of ground and surface waters. This work presents simple, rapid, sensitive and accurate determination of bentazone at unmodified boron-doped diamond electrode, using differential pulse voltammetry in Britton-Robinson buffer (pH 4, oxidation peak at 1.0 V). Under optimized DPV conditions linear calibration curve was obtained for range of 2 to 100 μM, with a detection limit of 0.5 μM. The effect of possible interfering agents is negligible, confirming good selectivity of the method. The method was successfully applied to determination of bentazone in spiked river water samples. This electrochemical determination of bentazone represents a favorable alternative to other used time-consuming and expensive analytical techniques and procedures. [ABSTRACT FROM AUTHOR]

The study presents a new approach for rapid and ultrasensitive detection of maltol using a glassy carbon electrode (GCE) modified with graphene oxide-wrapped tin oxide@carbon nanospheres (SnO 2 @C@GO). The morphological and components properties of SnO 2 @C@GO nanocomposites were investigated by means of X-ray diffraction spectroscopy, Raman spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy, and electrochemical impedance spectroscopy. SnO 2 @C@GO nanocomposite on a GCE had a synergetic effect on the electrochemical oxidation of maltol by means of square wave voltammetry. Under the optimum conditions, anodic peak current response of maltol was linear with its concentration in the range of 80 nM–10 μM, and a detection limit of 12 nM was achieved for maltol. The experiment results presented that the method showed good selectivity, sensitivity, reproducibility, and long-term stability, as well as excellent potential for use as an ideal inexpensive voltammetric method applicable for complex food matrices. [ABSTRACT FROM AUTHOR]

It was first time using the l-cysteine self-assembled on the surface of gold nanoparticles and Bi2O3 nano-structured materials modified GCE composed l-cysteine/AuNPs/Bi2O3/GCE sensor. The sensor possessed three-dimensional nanostructure and exhibited a higher ratio of activity sites, large active surface, fast electron transfer rate, excellent catalytic, sensing characteristics and larger affinity to Cu (II). The sensor was determined to have an excellent sensitivity and selectivity for the detection of Cu (II). The characterization of sensor as well as the optimization of the analytical procedure was reported. The optimized conditions parameters allowed the detection of Cu (II) concentration following short analysis time, a detection limit of 5×10−11 M at 80 s of preconcentration time was obtained using the as-prepared sensor, and also show excellent stability and good repeatability, and, thus, could be used for detection of Cu (II) in environment. [ABSTRACT FROM AUTHOR]

A sensitive electrochemical DNA biosensor was developed for Helicobacter pylori ( H. pylori ) detection using differential pulse voltammetry. Single-stranded DNA probe was immobilized on a graphene oxide/gold nanoparticles modified glassy carbon electrode (GO/AuNP s /GCE). A hybridization reaction was conducted with the target DNA and the immobilized DNA on the electrode surface. Oracet blue (OB) was selected for the first time as a redox indicator for amplifying the electrochemical signal of DNA. Enhanced sensitivity was achieved through combining the excellent electric conductivity of GO/AuNPs and the electroactivity of the OB. The DNA biosensor displayed excellent performance to demonstrate the differences between the voltammetric signals of the OB obtained from different hybridization samples (non-complementary, mismatch and complementary DNAs). The proposed biosensor has a linear range of 60.0–600.0 pM and a detection limit of 27.0 pM for detection of H. pylori . In addition, the biosensor have responded very well in the simulated real sample evaluations, signifying its potential to be used in future clinical detection of the H. pylori bacteria. [ABSTRACT FROM AUTHOR]

Novel mesoporous carbon fibers (MCFs) were fabricated through a self-templating strategy and solution growth process. MCF modified glassy carbon electrode (MCF/GCE) was proposed for the direct electrocatalytic and simultaneous determination of four DNA bases (guanine (G), adenine (A), thymine (T) and cytosine (C)) using differential pulse voltammetry (DPV) measurement. The MCF/GCE exhibits satisfactory electrocatalytic activity by significantly enhancing the oxidation peak currents and lowering the oxidation potentials toward the four bases when compared with those on GCE. Especially, MCF greatly accelerates the electron transfer of pyrimidine base, which have high oxidation potentials and slow electron transfer kinetics. Moreover, MCF/GCE realizes the simultaneous determination of four DNA bases with low detection limits, high sensitivity and wide linear range. More important, the proposed electrode was successfully applied in the direct detection of bases in herring sperm DNA sample with satisfactory results. Besides, the MCF/GCE shows good long-term stability and reproducibility. These superior performances of MCF/GCE toward purine and pyrimidine DNA bases provide a good possibility for applying the MCF/GCE in our further DNA biosensor research. [ABSTRACT FROM AUTHOR]

In this approach, Ba 0.5 Sr 0.5 Fe 12-2x (CoHf) x O 19 ferrite samples have been successfully prepared using the conventional solid-state method, and single hexagonal crystal structure of the M-type hexaferrite phase have been formed according to the space group No. 194 (P 63/mmc). The cation distribution in Ba 0.5 Sr 0.5 Fe 12-2x (CoHf) x O 19 has been defined. The bandgap energies of ferrite compositions are found to be 2.86, 2.83, 2.85, 2.89, 2.89, and 2.89 eV for different concentrations x = 0, 0.2, 0.4, 0.6, 0.8 and 1, respectively. The photocatalytic efficiencies were evaluated by degradation of an aqueous solution of Acridine Orange (AO) dye [0.03 mM] under visible light. Interestingly, the Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 at x = 0.4 exhibited the highest degradation rate of AO which was about 3.6 times larger than Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 at x = 0. The findings showed a slight decrease in the photocatalytic performance of compositions x = 0.0 after five cycles, indicating a stable photo-catalyst behavior. Additionally, a highly sensitive and selective electrochemical sensor on a glassy carbon electrode (GCE) for the detection of 4-nitrophenol (4-NP) has been fabricated with the similar Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 (x = 0.4) composition. The electrochemical linear responses of the 4-NP chemical sensor were studied over the concentration range (0.1 nM–0.01 mM), known as a linear dynamic range (LDR). The obtained slope from the calibration curve was applied in the calculation of the sensitivity (16.9114 μAμM−1cm−2), and detection limit (96.11 ± 4.81 pM) of the proposed 4-NP electrochemical sensor with Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 (x = 0.4) fabricated Nafion coated GCE. The Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 (x = 0.4)/Nafion/GCE sensor parameters were found to be reliable in performance of response time and repeatability in comparison to previous reports. Finally, the prepared Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 (x = 0.4) material is introduced in a new route by the photocatalytic and electrochemical approaches to remove colored and carcinogenic chemicals from the environmental and healthcare fields in a broad scale. [Display omitted] • Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 compound can be considered as multifunctional material. • The narrow bandgap energies of Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 showed effective response to visible light. • Ba 0.5 Sr 0.5 Co x Hf x Fe 12-2x O 19 could be applied as an effective photocatalyst for practical applications in pollutants treatment. • The selective 4-NP electrochemical sensor was fabricated by GCE coated with prepared material and the conductive nafion (5%) binder. [ABSTRACT FROM AUTHOR]

We conducted a clinical trial to analyze human serum containing carbamazepine by using the differential pulse voltammetry ( DPV) method with a glassy carbon electrode, and compared it with the fluorescence polarization immunoassay ( FPIA). Thirty patients, who visited our hospital to have their serum carbamazepine level checked, were enrolled. Ten mL of venous blood was collected from each patient and analyzed by DPV and FPIA methods. The correlation between the carbamazepine concentrations determined by DPV and FPIA was good, with an RSQ of 0.998. The similarity of the results indicates that these two methods can be used interchangeably. The DPV method using a glassy carbon electrode may be a potential alternative method to determine the carbamazepine level in human serum. [ABSTRACT FROM AUTHOR]

Abstract: Oxidative protein damage is the most critical factor implicated in carcinogenesis and other disorders. However, the electrochemical detection of oxidative protein damage and the protections of protein from damage by antioxidants have been reported rarely. In this work, a novel, sensitive and inexpensive method for direct electrochemical detection of bovine serum albumin (BSA) damage in aqueous solutions is described. The simple electrochemical procedure has been constructed on the glassy carbon electrode (GCE) surface by BSA direct adsorption technique. Co(bpy)3 3+ was used as a redox indicator to monitor BSA damage induced by hydroxyl radical (h was produced from Fenton reaction. The simplest fabrication procedure and the most classic method of free radical production were used to research the protein damage, demonstrating obvious virtues of brachylogy, rigor and precise. The electrochemical behaviors of the underlying electrodes were characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Ultraviolet–visible (UV–vis) spectroscopy was used to verify the BSA damage with the universal index of the protein carbonyl group content. The optimizations of the Fe2+/H2O2 ratio and incubation time on BSA damage were explored. Moreover, the protections of BSA from damage by antioxidants were investigated. These conclusions demonstrated that the proposed method could be used to detect protein damage induced by Fenton reaction through a simple electrochemical approach. [Copyright &y& Elsevier]

Abstract: A highly sensitive method was investigated for the simultaneous determination of dopamine (DA) and acetaminophen (AP) using acid functionalized multi-wall carbon nanotubes (f-MWCNTs) modified glassy carbon electrodes (GCEs). Both DA and AP were accumulated at the surface of f-MWCNTs modified GCE (under open circuit condition for 30s). In differential pulse voltammetry (DPV) technique both DA and AP give sensitive oxidation peaks at 125mV and 307mV, respectively. Under the optimized experimental conditions (such as supporting electrolyte pH, accumulation time and scanning rate, etc.) DA and AP give linear response over the range of 3–200μmolL−1 (r =0.992) and 3–300μmolL−1 (r =0.989), respectively. The lower detection limits were found to be 0.8 for DA and 0.6μmolL−1 for AP. The interfering species such as ascorbic acid (AA), uric acid (UA) and reduced form of Nicotinamide adenine dinucleotide (NADH) showed no interference with the selective determination of DA and AP. The investigated method showed good stability, reproducibility (1.3% (DA) and 2.3% (AP)), repeatability (1.9%) and high recovery in pharmaceutical preparation (1.7% (DA) and 2.7% (AP)), and human serum (1.7% (DA) and 1.9% (AP)). [Copyright &y& Elsevier]

An electrochemical sensor based on a cobalt oxide nanorod (Co3O4NR) modified glassy carbon electrode (GCE) (Co3O4NR-GCE) was prepared for simultaneous and selective determination of hydroquinone (HQ) and catechol (CT). Surface morphology and crystallinity of Co3O4NR were investigated employing field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. The structure (16 nm) of the Co3O4 nanorod was observed in the FESEM image. A sharp peak pattern in the XRD survey revealed the following crystal planes in Co3O4NR material: (111), (220), (311), (222), (400), (422), (511), and (440). Electrochemical characterization of modified Co3O4NR-GCE was carried out performing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Selective and simultaneous detection of HQ and CT was carried out by performing CV and differential pulse voltammetry (DPV) analysis. In both studies, modified Co3O4NR-GCE showed well defined oxidation and reduction peaks for HQ and CT with enhanced peak current, and the oxidation peaks for HQ and CT were observed at 0.152 V and 0.254 V, respectively, in the CV analysis. Scan rate and pH variation analysis were performed to evaluate different kinetic parameters, including charge transfer coefficient (α = 0.56 for HQ and 0.66 for CT), heterogeneous charge transfer rate constant (ks = 56 for HQ and 72 for CT), and the number of electrons involved in HQ and CT oxidation. Quantitative analysis of HQ and CT was studied by observing the current response of DPV analysis with respect to concentration variation. Here, the detection limit was calculated as 0.2 µM for HQ with a linear concentration range of 5–200 µM, and 0.4 µM for CT with a linear concentration range of 5–150 µM. The practical applicability of the proposed sensor was investigated using sample solutions prepared in tap water. The reported sensor showed impressive selectivity towards HQ and CT in the presence of common interferents. [ABSTRACT FROM AUTHOR]

The multiwalled carbon nanotube-nickel hydroxide composite film used to modify glassy carbon electrode was prepared and confirmed by transmission electron microscopy and cyclic voltammetry. The process and mechanism of film formation were discussed in detail. The electrode modified with the composite film exhibited good catalytic activity toward electrochemical oxidation of hydrogen peroxide in 0.1 mol/L sodium hydroxide solution. Various factors affecting the electrocatalytic activity of nickel hydroxide film were investigated. The anodic peak current increased with the increased concentration of hydrogen peroxide. The linear range for the determination of hydrogen peroxide was from 1.5 × 10-6 mol/L to 2.5 × 10-3 mol/L with the detection limit 6.1 × 10-7 mol/L (S/N = 3). And the proposed method was applied to the determination of hydrogen peroxide in disinfector with higher sensitivity and lower detection limit. [ABSTRACT FROM AUTHOR]

Abstract: Voltammetric behavior of Morin was studied in 0.1M HAc–NaAc+50mM KCl (pH 3.4) solution at glassy carbon electrode (GCE) using cyclic voltammetry (CV). Morin showed an irreversible anodic peak at 0.720V in CV which was involving two electrons and two protons. Also, the interaction of Morin with double-stranded calf thymus DNA (ctDNA) was studied by CV at GCE with an irreversible electrochemical equation. As a result of reaction with ctDNA, the voltammetric peak of Morin was a position shift and the peak current decreased. The diffusion coefficients of both free and binding Morin (D f =1.1086×10−7 cm2 s−1 and D b =8.2544×10−9 cm2 s−1), binding constant (K =1.7765×107 cm3 mol−1), and binding site size (s =0.8510) of the Morin–DNA complex were obtained simultaneously by non-linear fit analysis. The results demonstrate that Morin can bind to ctDNA in 0.1M HAc–NaAc+50mM KCl (pH 3.4) solution and the ring B of Morin intercalates between the DNA base pairs. [Copyright &y& Elsevier]

[Display omitted] • An electrochemical nitrofurantoin and nilutamide sensor was fabricated based on BZO/SCN/GCE. • This sensor showed high sensitivity, lower LOD, and good selectivity. • The nanocomposite enhanced performances of detecting nitrofurantoin and nilutamide. • Real-time monitoring was done in water and urine samples. In this study, a rhombic dodecahedral barium zirconate microcrystals decorated on sulphur-doped graphitic carbon nitride (BZO/SCN) composite was prepared by a hydrothermal (HT) method followed by ultrasonication, which was used for the sensitive and selective determination of nitrofurantoin (NFT, an antibacterial agent) and nilutamide (NLT, an anticancer drug). The nanocomposite structure and morphology were characterized by XRD, FE-SEM/TEM, FT-IR, and XPS techniques. CV, EIS, and DPV methods have also been employed to investigate the electrochemical performance of the nanocomposite. Analytical parameters such as loading amount of catalyst, effect of scan rate, electron rate kinetics (K s), diffusion coefficient (D), and pH value were analyzed. The BZO/SCN composite modified glassy carbon electrode (GCE) shows excellent detection of NFT and NLT in a wide dynamic linear range (WLR: 0.09–260.9 μM; 0.09–189.61 μM), a low limit of detection (LOD: 2 nM; 6 nM), and a sensitivity of (35.73 µA µM−1 cm2; 12.17 µA µM−1 cm2), respectively. Moreover, the fabricated electrode was further applied to the detection of the NFT and NLT in spiked real samples with satisfactory recoveries. [ABSTRACT FROM AUTHOR]

• SnO 2 -doped Ag 2 O nanorods (NRs) were synthesized by wet-chemical method. • NRs were deposited onto GCE using 5% nafion chemical binder. • NRs sensor probe was exhibited the highest sensitivity and lowest LDR. • Validated of NRs/Nafion/GCE sensor probe with real bio-samples. • Safety of health and biomedical fields. Here, a reliable electrochemical sensor prove was fabricated by SnO 2 -doped Ag 2 O nanorods (NRs) decorated glassy carbon electrode (GCE) to detect choline (CA) in the buffer phase. The wet-chemically synthesized SnO 2 -doped Ag 2 O NRs were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques respectively. SnO 2 -doped Ag 2 O NRs was layered as a film of NRs onto a GCE using Nafion adhesive to obtain the working electrode of the choline (CA) sensor. The proposed sensor is calibrated by using the concentration of CA versus measured current, which is found linear over a concentration range of CA (0.1 nM ~ 0.01 mM) defined as a dynamic range (LDR) for choline detection. Using LDR slope and the active surface of GCE (0.0316 cm2), the choline sensor sensitivity (95.1 µAµM-1cm−2) is calculated. The limit of detection (LOD) and limit of quantification (LOQ) of the proposed CA sensor are calculated using the signal-to-noise ratio at 3, and the obtained values are 95.9 ± 4.8 pM and 319.67 ± 5 pM respectively. The sensor reliability measuring parameters (response time, stability and reproducibility) are found satisfactory. In the end, the choline sensor with SnO 2 -doped Ag 2 O NRs/GCE is performed preciously in the electrochemical analysis of various real bio-samples to validate its real-time applicability. [ABSTRACT FROM AUTHOR]

• Two electrochemical signals of S. aureus suspension were detected. • The electrochemical signals of S. aureus were attributed to adenine and guanine. • Microbial viability was evaluated from the perspective of purine metabolism. • The inhibition of bacterial viability was evaluated by purine metabolism. Establishment of new method for evaluation microbial viability has become an urgent need in the fields of biology, medicine, environment and so on. In this paper, two electrochemical signals of Staphylococcus aureus (S. aureus) at + 0.693 and + 0.973 V vs. Ag/AgCl (sat. KCl) were detected on the multi-walled carbon nanotube modified glassy carbon electrode (MWCNTs/GCE), and attributed to the oxidation of guanine and adenine secreted by S. aureus. For the first time, bacterial viability was evaluated from the perspective of proliferation and purine metabolism. Compared with the plate counting method, the electrochemical signals of guanine and adenine showed an earlier change of viability when S. aureus entered stationary from logarithmic phase and apoptotic from stationary phase during the growth process of S. aureus. There were good linear relationships between electrochemical signals of guanine and adenine and the number of S. aureus cells in different growth phases, but there were different detection thresholds. At the logarithmic phase, S. aureu s had stronger viability and ability to metabolize purines, which resulted in a lower detection threshold. Both electrochemical signals of bacteria could well reflect the inhibition of levofloxacin on S. aureus viability, and the guanine signal peak was closer to the result of plate counting method. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• CdO/SnO 2 nanoparticles prepared by facile wet-chemical method. • Highly sensitive in-situ L-tyrosine sensor by reliable electrochemical method. • L-tyrosine-sensor exhibits the lower detection limit within short response time. • Practically validated the real biological serum samples. • Effective L-tyrosine -sensor for health care and biomedical fields. Here, the nanoparticles (NPs) of CdO/SnO 2 were prepared by co-precipitation method in alkaline phase at low temperature. The characterization of CdO/SnO 2 NPs were analyzed by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analysis. To fabricate the sensor, glassy carbon electrode (GCE) was coated by CdO/SnO 2 NPs with 5% nafion suspension. The resulted sensor was applied to detect L-Tyrosine (L-Tyr) in buffer phase. A linear relation current versus concentration known as calibration curve was made. The sensor sensitivity (11.848 µA µM−1 cm−2) is calculated from the slope of calibration curve. Recognizing the maximum linear region in calibration curve (regression coefficient R2 = 0.99), the linear dynamic range (0.1 nM–0.01 mM) is used. Finally, the lower limit of detection (97.93 ± 4.89 pM) is estimated by applying the signal to noise ratio of 3 from the calibration curve. During the sensing performances, it was found as reliable, reproducible and long-term stable sensor and validated to detect the real biological samples by electrochemical approach in room conditions. [ABSTRACT FROM AUTHOR]

In this approach, RuO 2 doped ZnO nanoparticles (NPs; 10% RuO 2 doping) were prepared by wet-chemical method and characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDS), and Field Emission Scanning Electron Microscopy (FESEM). The slurry of RuO 2 -doped ZnO NPs in ethanol was deposited as thin film of onto a glassy carbon electrode (GCE) to result in a working electrode to be used for l -glutamic acid (L-GA) sensing probe. The electrochemical response of the sensor was found to be linear in the range of 0.1 nM–0.01 mM in current versus logarithm of concentration plot, called 'linear dynamic range (LDR)'. The sensitivity of the electrode is found to be 5.42 μAμM−1cm−2. The detection limit is estimated to be 96.0 ± 5.0 pM by using signal-noise ratio of 3. The proposed L-GA sensor has shown excellent reproducibility, good stability and fast response time. It is successfully used to analyze the selective biological sample with the RuO 2 -doped ZnO nanoparticles fabricated sensor matrix. Thus, this methodology for developing enzyme-less sensor would be the most reliable, efficient, and simple route in the field of healthcare sector in broad scales. Image 1 • RuO 2 doped ZnO nanoparticles were synthesized by wet-chemical method. • NPs were deposited on GCE by using 5% nafion chemical binder. • l -glutamic acid was detected with RuO 2 doped ZnO NPs. • Sensor exhibited the highest sensitivity and lowest detection limit. • Biomedical and health safety. [ABSTRACT FROM AUTHOR]

• Germanium-doped zinc oxide composite nanoparticles was prepared. • A fast response and high selectivity toward 4-Aminophenol were realized. • Exhibited sensor sensitivity was 0.5063 µA cm−2 µM−1. • Found sensor lowest detection limit was 0.5925 ± 0.02 nM. • Safety of environment and healthcare fields. The present study aims to fabricate and investigate the germanium-doped zinc oxide (Ge/ZnO) composite nanoparticles (NPs) coated gassy carbon electrode (GCE) sensor by electrochemical method. The performances including sensitivity, stability, lower detection limit, reliability, and reproducibility were evaluated in details at room conditions. Electrochemical method was employed to deposit Ge/ZnO NPs on flat GCE in the presence of 5% nafion (conducting binders) for fabricating the sensor matrix, which exhibited the fast response towards hazardous 4-Aminophenol (4AP) chemical. UV/vis, FT-IR, EDS, XRD, FESEM, and XPS were used to characterize the prepared Ge/ZnO NPs. Electrochemical method is employed to investigate the current response in detecting 4AP chemical at room conditions. Results show that the current response of Ge/ZnO NPs coated GCE sensor precisely changes, which directly depended on the target concentration as well as the type of the target analyte existed in solution. The sensitivity and detection limit are calculated from the slope of calibration curve by considering the active surface area of fabricated electrode, which are found as 0.5063 µA cm−2 µM−1 and 0.5925 ± 0.02 nM respectively. The measured performances are found to be good and in some cases, better than those of other sensor materials reported in literatures. The developed chemical sensors could be efficiently applied to detect the phenolic derivatives for green environment by ensuring safety in broader scales. [ABSTRACT FROM AUTHOR]

Schematic representation showing (a) Ag 2 O·SnO 2 ·TiO 2 nanomaterials coated GCE with conducting nafion (5 % ethanol) coating binders, (b) expected I–V response by the Ag 2 O·SnO 2 ·TiO 2 nanomaterials/GCE, (c) observed electrochemical response by the Ag 2 O·SnO 2 ·TiO 2 nanomaterials/GCE, and (d) proposed detection mechanism of TU, while TU is reduced by removing conducting electrons from the Ag 2 O·SnO 2 ·TiO 2 nanomaterials/GCE electrodes. • Synthesized multifunctional nanomaterial with high dye degradation efficiency. • Ag 2 O·SnO 2 ·TiO 2 /Nafion/GCE sensor assembly determine Thiourea from 0.10 nM to 0.10 M. • Sensitivity and LOD were obtained as 4.2913 μAμM−1 cm−2 and 2.3 ± 0.1 pM (S/N = 3). • Anti-bacterial activity against Gram positive and Gram negative bacteria observed. A novel multifunctional material with high dye degradation efficiency, photoluminescence (PL) and electro-sensing ability was synthesized with a simple co-precipitation method followed by thermal calcination. The dye degradation efficiency was 98% at pH 9 within only 60 min. The material also showed excellent anti-bacterial activity against both Gram positive and Gram negative bacteria in the presence and absence of light. For the electro-sensor application of Ag 2 O·SnO 2 ·TiO 2 , glassy carbon electrode (GCE) was modified by the Ag 2 O·SnO 2 ·TiO 2 nanomaterials at room conditions. The resulting Ag 2 O·SnO 2 ·TiO 2 /Nafion/GCE sensor assembly was employed to determine Thiourea (TU) by a simple and reliable electrochemical approach at low-potential. Hazardous TU was selected as the target analyte by the selectivity study. In the investigative study, for the TU concentrations of 0.10 nM to 0.10 M, the calibration plot was found linear (r2 = 0.9997). Calculated sensitivity and limit of detection values were obtained as 4.2913 μAμM−1 cm−2 and 2.3 ± 0.1 pM (S/N = 3) respectively. [ABSTRACT FROM AUTHOR]

A reliable and highly sensitive dopamine sensor was fabricated with mixture of Al–Mn–Cr-oxide (the composition is found as AlMn 0.65 Cr 1.76 O 7.47) nanoparticles (NPs). The wet-chemically synthesized NPs was deposited onto a glassy carbon electrode (GCE) as a layer of thin film using conductive 5% Nafion suspension in ethanol as a chemical binder. The assembled AlMn 0.65 Cr 1.76 O 7.47 NPs/binder/GCE sensor was selective towards dopamine and was implemented to analyze a number of dopamine solutions with various concentration. The electrochemical response of the sensor was found to be indifferent to the presence of electrolytes like Na+, K+, Ca2+ and Fe2+ in the analyte-samples. The electrochemical response of the sensor was reproducible in replicate runs at a single time of use as well as in usage at different time-intervals. The I vs. log C plot was linear over a range of as wide as 0.1 nM- 0.01 mM. The sensitivity of the assembled electrode at the applied potential +1.5 V was found to be 55.8165 μAμM−1cm−2, while the detection limit was 96.87 ± 4.84 pM. The fabricated sensor was detected the dopamine effectively and measured it in the real biological samples precisely. Thus, the present approach to developing sensors has acquired immense potential significance for future application in biomedical sector. Image 1 • AlMn 0.645 Cr 1.76 O 7.47 NPs were synthesized by wet-chemical method. • NPs were deposited on GCE by using 5% nafion chemical binder. • Sensor was exhibited the highest sensitivity and lowest detection limit. • Validated with real bio-samples samples. • Biomedical and health safety. [ABSTRACT FROM AUTHOR]

• A simple analytical method for the determination of DNA nucleobases. • Enhanced sensitivity for electrochemical detection using PANI-MoS 2 /CPE. • The effects of supporting electrolyte, concentration, and pH were investigated. • Low limit of detection of the electrochemical biosensor with favorable R2. Robust detection of DNA as a molecule that encodes genetic instructions is getting significant attention in recent years due to its promising applications in diseases diagnosis and treatment, forensic analysis, food safety evaluation, environmental monitoring, and so on. In this research, a simple, rapid and multiplex electrochemical method based on single-layer molybdenum disulfide (MoS 2) nanosheets sensing platform and differential pulse voltammetry (DPV) method for detection of DNA nucleobases (DNANBs) was set up without any pretreatment or separation process. Hence, the carbon paste electrode modified with MoS 2 (MoS 2 /CPE) was selected, and the effects of different parameters such as supporting electrolyte composition and pH were optimized to obtain the best peak potential separation and high sensitivity. Then, the individual, respective and simultaneous determinations of DNANBs were performed by controlling the certain experimental conditions. The results exhibited the excellent sensitivity, low limit of detection, and high selectivity of the electrochemical biosensor. Moreover, the peak current values were linearly dependent on the concentration of DNANBs. For comparison, common methods for determination of DNANBs were analyzed based on the absorption of ultraviolet light and Raman spectroscopy. Finally, the proposed electrode was modified with polyaniline (PANI-MoS 2 /CPE) as a new biosensor for the determination of DNANBs, exhibiting good reproducibility and stability. [ABSTRACT FROM AUTHOR]