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In the current study, a nanoscale perovskite SrFeO (SrFNPs) was synthesized by a rapid microwave-assisted co-precipitation method and characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, scanning electron microscopy, Energy dispersive X-ray, and vibrating sample magnetometer techniques. Modified glassy carbon electrode with Pt nanoparticles (PtNPs), functionalized carbon nanotubes (CNTs), and SrFNPs as multifunctional catalyst is prepared and its catalytic activity toward methanol oxidation is investigated. Based on the electrochemical studies, a PtNPs-CNTs-SrFNPs nanocomposite was shown a considerable activity for methanol oxidation in comparison of PtNPs, PtNPs-CNTs, and PtNPs-SrFNPs. A direct methanol fuel cell was designed, assembled, and tested with suggested PtNPs-CNTs-SrFNPs nanocomposites under several different conditions. The effect of some experimental factors such as temperature, methanol concentration, and flow rate as well as NaOH concentration on electrical performances of fuel cell were studied and optimized. [ABSTRACT FROM AUTHOR]

The interaction of DNA with [Y(bpy)(OH 2 ) 6 ] +3 , where bpy is 2,2′-bipyridine has been studied at physiological pH in Tris–HCl buffer. Fluorescence and absorption spectroscopy, agarose gel electrophoresis as well as EB quenching experiments are used to study DNA binding of the complex. The results reveal that DNA have the strong ability to bind with Y(III) complex. The binding constant, K b and the Stern–Volmer quenching constant, K SV are determined. For characterization of the binding mode between the Y(III) complex and DNA various procedures such as: iodide quenching assay, salt effect and thermodynamical investigation are used. The results suggest that minor groove binding should be the interaction mode of complex to DNA. A gel electrophoresis assay demonstrates the ability of the complex to cleave the DNA via oxidative pathway. Electronic structure of [Y(bpy)(OH 2 ) 6 ] +3 was also carried out applying the density functional theory (DFT) method and applied to explain some obtained experimental observations. [ABSTRACT FROM AUTHOR]

In this proof-of-concept study, we reported the incorporation of a graphene oxide hydrogel (GO-gel) electrolyte as the cathode and the electropolymerized aniline (E-PANI) in situ on a titanium oxide (TiO 2)-coated fluorine-doped tin oxide (FTO) as the anode in an organic solar cell (OSC) for the first time, to the best of our knowledge. Fourier-transform infrared (FT-IR) microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were applied for characterization studies. The incorporation of GO-gel electrolyte within E-PANI significantly enhanced the power conversion efficiency (PCE) by 257.0% compared to the standard E-PANI solar cell with a liquid electrolyte. Under an AM 1.5 G (100 mW/cm2) illumination, the final OSC (FTO│TiO 2 /E-PANI/GO-gel-I-/I 3 −│Al) demonstrated an overall PCE of 4.35% with an open circuit voltage (V oc) of 0.889 V and a short circuit current density (J sc) of 15.13 mA/cm2. The photovoltaic properties were found to be superior to those of the previously reported E-PANI-based solar cells. Our preliminary results showed that the rheological properties, PCE and stability were significantly enhanced with the incorporation of GO-gel electrolyte. Thus, GO-gel electrolytes provide a promising platform for the development of high-efficiency photovoltaic devices in the near future. [Display omitted] • A graphene oxide (GO) hydrogel iodide/triiodide electrolyte was synthesized. • The GO hydrogel electrolyte was incorporated into a solar cell. • The electropolymerized PANI was utilized as the active layer. • The stability of the solar cell was enhanced in the presence of GO hydrogel electrolyte. • A PCE of 4.35% was recorded for the polymer solar cell. [ABSTRACT FROM AUTHOR]

This work investigates the efficiency and possibility of modified nanoscale zeolite with baloform for removing of arsenate anions from wastewaters. A combination of scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, Thermogravimetric-differential thermal analysis and Brunauer–Emmett–Teller surface area were used for characterization of zeolitic materials. Effects of different parameters such as pH and dosage of adsorbent, on the arsenate removing yield are studied. The yield of arsenate removing increases by increasing dosage of adsorbent and contact time. The results show that arsenate removal efficiency from wastewaters is higher than 99% at optimum conditions. The adsorption data of the modified zeolite for arsenate removing was consistent with six isotherm equations (Freundlich, Langmuir, Langmuir–Freundlich, Dubinin–Radushkevich, Redlich–Peterson and Toth). The obtained modeling results indicated that, although the three-parameter models, taking into account the surface heterogeneity, provided the closest approach to the measurement data, the parameters estimates could be highly biased. Batch experiments were carried out to study the removal kinetics of arsenate. The kinetic studies proved that the Elovich was the applicable model. [ABSTRACT FROM AUTHOR]

Abstract: Incorporation of LaFeO3 nanoparticles (LaFeO3NPs) and carbon nanotubes (CNT) into Pt–chitosan for methanol electrooxidation has been studied. LaFeO3 nanoparticles are successfully prepared by a rapid microwave-assisted co-precipitation method. The formation of LaFeO3NPs is confirmed by X-ray powder diffraction (XRD), Fourier transformed infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) techniques. Modified glassy carbon (GC) with Pt nanoparticles (PtNPs), LaFeO3NPs and chitosan (CH) as binder (GC/PtNPs–LaFeO3NPs–CH) and GC/PtNps–LaFeO3NPs–CNT–CH electrodes are prepared by layer by layer technique and their catalytic activity toward methanol oxidation is investigated. It is demonstrated that the catalytic activity of PtNPs can be significantly enhanced by mixing with LaFeO3NPs and CNT. The Pt–LaFeO3NPs–CNT catalyst has a better durability compared to the Pt–LaFeO3NPs catalyst due to the existence of CNT, which prevents dissolution of PtNPs. Moreover, PtNPs–LaFeO3NPs–CH shows improved methanol oxidation activity, but its direct methanol fuel cells (DMFC) performance is found to be inferior to that measured for PtNps–LaFeO3NPs–CNT–CH. The factor influencing PtNPs utilization in the methanol oxidation reaction is intrinsically related to PtNPs formation but using LaFeO3NPs helps in enhancing the DMFC performance with low Pt loading. [Copyright &y& Elsevier]

Incorporation of palladium nanoparticles (PdNPs) and multi-walled carbon nanotubes (MWCNTs) into chitosan-coated glassy carbon (GC) electrode for alcohols (methanol, ethanol, and isopropanol) electrooxidation has been studied. PdNPs-chitosan and MWCNTs-PdNPs-chitosan nanocomposites are successfully prepared and characterized by transmission electron microscopy images and UV-Vis spectroscopy. Based on the results, PdNPs-chitosan nanocomposite indicates high electrochemical activity and excellent catalytic characteristic for alcohol (C-C) electrooxidation on a GC electrode in an alkaline medium. The current density of the alcohols oxidation at GC-PdNPs-chitosan electrode is investigated in optimized conditions and compared with that obtained at the GC-modified electrode by Pd with different polymers. Also, our results show that the dispersion of Pd nanoparticles on the MWCNTs significantly improved the performance of the PdNPs/chitosan composite for electrooxidation of the C-C alcohols. [ABSTRACT FROM AUTHOR]

Abstract: The photoluminescence properties of a Tb(III) complex of the form [Tb(phen)2Cl3·OH2] (phen=1,10-phenanthroline) in different solvents are presented. It shows the characteristic luminescence of the corresponding Ln3+ ion in the visible region. The emission intensity of this complex in coordinating solvent is higher than non-coordinating one. The suggested mechanism for the energy transfer between the ligand and Tb3+ ion is the intramolecular energy transfer mechanism. The interactions of the Tb(III) complex with fish salmon DNA are studied by fluorescence spectroscopy, circular dichroism study and viscosity measurements. The results of fluorescence titration reveal that DNA strongly quenches the intrinsic fluorescence of the complex through a static quenching procedure. The binding constant (K b ) of the above metal complex at 25°C is determined by the fluorescence titration method and it is found to be M−1. The thermodynamic parameters (ΔH0>0, ΔS0>0 and ΔG0<0) indicate that the hydrophobic interactions play a major role in DNA–Tb complex association. The results support the claim that the title complex bonds to FS-DNA by a groove mode. [Copyright &y& Elsevier]

Highlights: [•] Interaction of [Dy(phen)2(OH2)3Cl]Cl2⋅H2O with DNA has been studied. [•] Intrinsic binding constant and the binding site number were determined by emission measurements. [•] Thermodynamic parameters indicate that the binding reaction is endothermic and spontaneous. [•] Our studies suggest that the major binding mode should be groove binding. [•] Dy(III) complex shows good antimicrobial activity against different bacteria. [Copyright &y& Elsevier]

A novel biosensor has been constructed by incorporating modified nanosized natural zeolite and 3-hydroxypropanaminium acetate (HPAA) as a novel room temperature ionic liquid, supported on multiwalled carbon nanotube (MWCNTs) and employed for the simultaneous determination of dopamine (DA) and uric acid (UA). A detailed investigation by transmission electron microscopy and electrochemistry is performed in order to elucidate the preparation process and properties of the composites. The voltammetric studies using the modified carbon paste electrode show two well-resolved anodic peaks for DA and UA with a potential difference of 160 mV, revealing the possibility of the simultaneous electrochemical detection of these compounds. The modified carbon paste electrode shows good conductivity, stability, and extraction effect due to the synergic action of HPAA, MWCNTs, and iron ion-doped natrolite zeolite. Under optimized conditions, the peak currents are linear from 8.12 × 10 to 3.01 × 10 mol L and from 9.31 × 10 to 3.36 × 10 mol L with detection limits of 1.16 × 10 and 1.33 × 10 mol L for DA and UA using the differential pulse voltammetric method, respectively. Finally, the modified carbon paste electrode proved to have good sensitivity and stability and is successfully applied for the simultaneous determination of DA and UA in human blood serum and urine samples. [ABSTRACT FROM AUTHOR]

A nanoscale catalyst Fe(FeNPs) supported on the natrolite zeolite nanoparticles (NANPs) is successfully synthesized and characterized by FT-IR, X-ray diffraction (XRD) and scanning electron microscopy (SEM) and thermogravimetric-differential thermal analysis (TG-DTA). The photodegradation of methyl orange (MO) is studied in aqueous suspension containing the catalyst under UV irradiation and HO. The effect of various reaction parameters such as initial dye concentration, irradiation time, pH, HO concentration and catalyst dosage on the decolorization of methyl orange is investigated. The degradation study reveals that the reactivity of the catalysts is in order of: photo-NANPs-FeNPs-HO > photo-NANPs-HO > photo-NANPs-FeNPs > photo-HO > NANPs-FeNPs-HO. The results show that methyl orange can be effectively decolorized by NANPs-FeNPs via the pseudo-first-order kinetic model. [ABSTRACT FROM AUTHOR]

Abstract: Nanosized perovskite LaFe0.7Co0.3O3 (LFCO) is synthesized through conventional co-precipitation method and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. The incorporation effect of the mentioned perovskite to catalytic activity of the PtNPs-MWCNTs-nafion (or -chitosan) catalyst toward methanol oxidation has been studied by cyclic voltammetry. Based on the electrochemical studies, all MWCNTs-PtNPs-nafion (or chitosan) and MWCNTs-PtNPs-LFCO-nafion (or chitosan) catalysts show a considerable activity for methanol oxidation. However, a synergistic effect is observed when LFCO is added to the catalyst by decreasing the poisoning rate of the Pt catalyst. [Copyright &y& Elsevier]

Abstract: Characterization of the interaction between yttrium(III) complex containing 1,10-phenanthroline as ligand, [Y(phen)2Cl(OH2)3]Cl2⋅H2O, and DNA has been carried out by UV absorption, fluorescence spectra and viscosity measurements in order to investigate binding mode. The experimental results indicate that the yttrium(III) complex binds to DNA and absorption is decreasing in charge transfer band with the increase in amount of DNA. The binding constant (Kb ) at different temperatures as well as thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°), were calculated according to relevant fluorescent data and Vant’ Hoff equation. The results of interaction mechanism studies, suggested that groove binding plays a major role in the binding of the complex and DNA. The activity of yttrium(III) complex against some bacteria was tested and antimicrobial screening tests shown growth inhibitory activity in the presence of yttrium(III) complex. [Copyright &y& Elsevier]

Electrooxidation of alcohols including methanol, ethanol, and isopropanol is studied on the modified solid glassy carbon electrodes with various amounts of platinum nanoparticles (PtNPs) immobilized on a composite of functionalized multi-walled carbon nanotubes (MWCNTs) and chitosan in an acidic solution. Here the chitosan is available as a binder to tightly anchor Pt nanoparticles onto the MWCNTs surfaces. MWCNTs/chitosan composite support can significantly improve the activity of the catalyst for alcohol oxidation and reduce the Pt catalyst loading. The calculated electrochemical active surface area is 379.2 m/g Pt for PtNP-MWCNT/chitosan. Cyclic voltammetry and chronoamperometry techniques are employed for catalytic activity evaluation. The effects of operational parameters including platinum loading, concentration of the corresponding alcohol, concentration of the acid solution, scanning rate, and the final limit of anodic potential on the performance of the electrodes are also investigated. [ABSTRACT FROM AUTHOR]

In this proof-of-concept study, a novel hybrid nanomaterial-based electrochemical sensor was developed for the simultaneous detection of four DNA bases. For the modification of the working electrode surface, graphene oxide quantum dots (GOQDs) were synthesized using a solvothermal method. GOQDs were then used for the preparation of a hybrid nanomaterial with multi-walled carbon nanotubes (GOQD-MWCNT) using a solvothermal technique for the first time. Transmission electron microscopy (TEM) was used to characterize the GOQDs-MWCNTs. A glassy carbon electrode (GCE) was modified with the GOQDs-MWCNTs using Nafion™ to prepare a GOQD-MWCNT/GCE for the simultaneous determination of four DNA bases in phosphate buffer solution (PBS, pH 7.0) using differential pulse voltammetry (DPV). The calibration plots were linear up to 50, 50, 500, and 500 µM with a limit of detection at 0.44, 0.2, 1.6, and 5.6 µM for guanine (G), adenine (A), thymine (T) and cytosine (C), respectively. The hybrid-modified sensor was used for the determination of G, A, T, and C spiked in the artificial saliva samples with the recovery values ranging from 95.9 to 106.8%. This novel hybrid-modified electrochemical sensor provides a promising platform for the future development of a device for cost-effective and efficient simultaneous detection of DNA bases in real biological and environmental samples. [ABSTRACT FROM AUTHOR]

Abstract: Several novel mixed ligand lanthanum complexes with 1,10-phenantroline and phenylcyanamide derivatives with the formula of [La(phen)3Cl3·OH2] (1) and [La(phen)3L3] (phen=1,10-phenantroline; L=2-clorophenylcyanamide (2), 2,5-dichlorophenylcyanamide (3), 2,4-dichlorophenycyanamide (4) and 2,4,5-trichorophenycyanamide (5)) are successfully synthesized in aqueous solution. The complexes are characterized by spectroscopic analysis such as infrared, 1H NMR, UV–Vis spectroscopy as well as elemental analysis. The molecular structure of 3 is determined by single-crystal X-ray diffraction method. Three 2,5-Cl2pcyd and three phenanthroline ligands are coordinated to the central La atom in monodentate and bidentate manner, respectively. [Copyright &y& Elsevier]

Abstract: The evaluation of a novel modified glassy carbon electrode modified with iron ion-doped natrolite zeolite-multiwalled carbon nanotube for the simultaneous and sensitive determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp) has been described. The measurements were carried out using cyclic voltammetry in buffer solution with pH 1. This modified electrode exhibits potent and persistent electroxidation behavior followed by well-separated oxidation peaks towards AA, DA, UA and Trp with increasing of the oxidation current. For the quaternary mixture containing AA, DA, UA and Trp, the 4 compounds can well separate from each other at the scan rate of 100mVs−1 with a potential difference of 270mV, 150mV and 260mV for the oxidation peak potentials of AA–DA, DA–UA and UA–Trp, respectively, which was large enough to simultaneous determine AA, DA, UA and Trp. The catalytic peak current obtained, was linearly dependent on the AA, DA, UA and Trp concentrations in the range of 7.77–833μM, 7.35–833μM, 0.23–83.3μM and 0.074–34.5μM and the detection limits for AA, DA, UA and Trp were 1.11, 1.05, 0.033 and 0.011μM, respectively. The analytical performance of this sensor has been evaluated for simultaneous detection of AA, DA, UA and Trp in human serum and urine samples. [Copyright &y& Elsevier]

Abstract: The main purpose of our research is focused to increase anodic catalysts activity and thus to decrease noble metal loading in anodes for electrooxidation of methanol. Binary and ternary catalysts dispersed in chitosan, Pt–Ni, Pt–Sn and Pt–Ni–Sn are synthesized by reduction of appropriate metal salts with NaBH4 in the chitosan solution. UV–vis spectra and transmission electron microscopy (TEM) images of the catalysts reveal the presence of metal nanoparticles (NPs). Performance of Pt–Ni, Pt–Sn, and Pt–Ni–Sn nanocomposites for methanol electrooxidation are examined by cyclic voltammetery and chronoamperometry methods. The effect of some experimental factors such as methanol, chitosan and electrolyte (H2SO4) concentrations, Ni and Sn amounts dispersed in chitosan on the current density and potential for the oxidation of methanol are studied and optimized. The electrochemical measurements show that the activity of Pt–Ni–SnNPs catalyst for methanol electrooxidation is higher than the activity of PtNPs, Pt–NiNPs and Pt–SnNPs catalysts. [Copyright &y& Elsevier]

Abstract: The binding of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline, [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)), to DNA has been investigated by absorption, emission, and viscosity measurements. The complexes show absorption decreasing in charge transfer band, fluorescence decrement when bound to DNA. The binding constant K b has been determined by absorption measurement for both complexes and found to be (6.76±0.12)×104 for 1 and (1.83±0.15)×104 M−1, for 2. The fluorescence of [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)) has been studied in detail. The results of fluorescence titration reveal that DNA has the strong ability to quenching the intrinsic fluorescence of Nd(III) and Pr(III) complexes through the static quenching procedure. The binding site number n, apparent binding constant K b and the Stern–Volmer constant k SV are determined. Thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°), are calculated according to relevant fluorescent data and Van’t Hoff equation. The experimental data suggest that the complexes bind to DNA by non-intercalative mode. Major groove binding is the preferred mode of interaction for [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)) with DNA. [Copyright &y& Elsevier]

Abstract: The sensitive determination of cyanide in wastewaters using modified GC electrode with silver hexacyanoferrate nanoparticles (SHFNPs) immobilized on multiwall carbon nanotube (MWCNT) was reported. The immobilization of SHFNPs on MWCNT was confirmed by transmission electron microscopy (TEM). The TEM image showed that the SHFNPs retained the spherical morphology after immobilized on MWCNT. The size of SHFNPs was examined around 27nm. The GC/MWCNT-SHFNPs was used for the determination of cyanide in borax buffer (BB) solution (pH 8.0). Using square wave voltammetry, the current response of cyanide increases linearly while increasing its concentration from 40.0nM to 150.0μM and a detection limit was found to be 8.3nM (S/N=3). The present modified electrode was also successfully used for the determination of 5.0μM cyanide in the presence of common contaminants at levels presenting in industrial wastewaters. The practical application of the present modified electrode was demonstrated by measuring the concentration of cyanide in industrial wastewater samples. Moreover, the studied sensor exhibited high sensitivity, good reproducibility and long-term stability. [ABSTRACT FROM AUTHOR]

Abstract: The fluorescence of praseodymium(III) complex containing 2,2′-bipyridine, [Pr(bpy)2Cl3·OH2] has been investigated in details. Also, the biological activity of [Pr(bpy)2Cl3·OH2] has been evaluated by examining its ability to bind to DNA with UV–vis, fluorescence as well as viscosity measurement. The fluorescence of [Pr(bpy)2Cl3·OH2] is strongly quenched through static mechanism in the presence of DNA. DNA intrinsic binding constant, K b the binding site number, n the Stern–Volmer quenching constant, K SV and the thermodynamic parameters have been determined by fluorescence spectroscopy. For characterization of bonding mode, the effect of various experimental parameters were investigated on the interaction of [Pr(bpy)2Cl3·OH2] with DNA. [Copyright &y& Elsevier]

Abstract: The interaction of [Nd(bpy)2Cl3·OH2], where bipy is 2,2′-bipyridine, with DNA has been studied by absorption, emission, and viscosity measurements. [Nd(bpy)2Cl3·OH2] showed absorption decreasing in charge transfer band with increasing of DNA. The binding constant, K b has been determined by absorption measurement and found to be (1.5±0.1)×105 M−1. The fluorescent of [Nd(bpy)2Cl3·OH2] has been investigated in detail. The interaction was also studied by fluorescence quenching technique. The results of fluorescence titration revealed that DNA had the strong ability to quenching the intrinsic fluorescence of Nd(III) complex at 327nm. The binding site number n, apparent binding constant K b and the Stern–Volmer quenching constant K SV have been determined. Thermodynamic parameters have been calculated according to relevant fluorescent data and Van’t Hoff equation. Characterization of bonding mode has been studied. The results suggested that the major interaction mode between [Nd(bpy)2Cl3·OH2] and DNA was groove binding. [Copyright &y& Elsevier]

Abstract: The effect of pyrazine as axial ligand on the formation and coordination of heme analogue has been studied. A new six coordinate and stable iron(III) heme analogue, [OEPFeIII(Pz)2]ClO4, where OEP is octaethylporphyrin and Pz is pyrazine, has been isolated. The compound has been characterized by different spectroscopic methods 1H NMR, UV–Vis, IR as well as elemental analysis. 1H NMR spectroscopy and magnetic moment measurements show that [OEPFeIII(Pz)2]ClO4 is paramagnetic and iron is six coordinate. The structure of [OEPFeIII(Pz)2]ClO4 has been determined by X-ray diffraction analysis. The four Fe–Np, bond distances have average values of 1.985Å. [Copyright &y& Elsevier]

An optical sensor for the direct measurement of silver was developed. The basic element of this optode is the immobilization of diphenylthiocarbazone on a triacetyl cellulose membrane. This optode has a linear range of up to 40 μg mL-1 o f Ag+ ions, with a limit of detection of 0.01 μg mL-1. The response time of the optode was 4-7 min, depending on the concentration of Ag+ ions. [ABSTRACT FROM AUTHOR]

A pneumatic flow injection-tandem spectrometer system, without a delivery pump, was used for the speciation of manganese (Mn). In this system the suction force of the pneumatic nebulizer of a flame atomic absorption spectrometer (FAAS) was used for solution delivery through the manifold. Mn(VII) and total Mn (Mn(VII) and Mn(II)) concentrations were determined using a UV-Vis spectrometer and FAAS, respectively. The Mn(II) concentration was determined by the difference between the two. The calibration curves were linear up to 15.00 mg L-1 for Mn(VII) and total Mn, with a detection limit of 0.08 mg L-1 and 0.05 mg L-1 for Mn(VII) and Mn, respectively. The mid-range precision and accuracy were < 1.89% and ± 2.50% for the 2 species, respectively, at a sampling rate of 80 samplings h-1. This system was used for the determination of Mn(VII) and Mn(II) in spiked and natural water, as well as industrial water. [ABSTRACT FROM AUTHOR]

A symmetric Ni(II) tetraaza macrocycle modified glassy electrode shows electrocatalytic activity for the oxidation of L-ascorbic acid at pH 7. It was shown the peak potential shifted to the negative by 250 mV compared with that for the bare electrode in the cyclic voltammograms. The calibration curve was linear up to 5 mM with a detection limit of 2.5 x 10-4 mM and RSD% better than 2.8%. Excipients used as additives in pharmaceutical formulations and foods did not interfere in the proposed procedure. This new modified electrode was applied to commercial pharmaceutical tablets, injections and foods. The obtained results were identical to those obtained by the classical 2,6-dichlorophenolindophenol method. [ABSTRACT FROM AUTHOR]

A spectrophotometric procedure for the determination of ascorbic acid in pure form and in a number of pharmaceutical preparations and real samples has been developed that offers the advantages of simplicity, accuracy, precision and sensitivity over many other methods. The method is based on the oxidation of ascorbic acid by a known excess amount of potassium chromate followed by the estimation of the unreacted amount of chromate by reactions with sym-diphenylcarbazide. The reacted oxidant corresponds to the ascorbic content. At the maximum absorption of 548 nm, Beer's law is obeyed up to 5 µg/mL of ascorbic acid. Statistical treatment of the experimental results indicates that the procedure is precise and accurate. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedure. The reliability of the method was established by parallel determination against the 2,6-dichlorophenolindophenol methods. The procedure described was successfully applied to the determination of bulk drugs, in pharmaceutical formulations and real samples. [ABSTRACT FROM AUTHOR]

A flow injection analysis (FIA)-background correction method comprising two solid-phase reactors and spectrophotometry for determination of ascorbic acid (AsA) is proposed. A polyethylene mini-column filled with solid iodine (30% m/m suspended on silica gel beads), reactor 1, and other column filled only with silica gel, reactor 2, which are then incorporated in a flow system so that solid iodine reagent in reactor 1 is affected as the sample passes through the column. The sample blank is produced by the oxidation of the AsA by iodine to form dehydroascorbic acid, insensitive to ultraviolet at 267 nm. AsA in samples is determined after injected in reactor 2; the difference in two analytical signal observed is related to amount of AsA. The linear range of the system is up to 50 μg ml−1 with a detection limit of 0.08 μg ml−1, R.S.D. of better than 1.0% and sampling frequency of 110 sample h−1. The method is successfully applied to the determination of AsA in pharmaceuticals and foods. [Copyright &y& Elsevier]

Deals with a study which presented the flow injection speciation of manganese in aqueous solution using a spectrophotometry method of detection. Experimental details; Results and discussion.

[Display omitted] In this research, the biological properties of the yttrium (III) (Y) complex, with 2,9-dimethyl- 1,10-phenanthroline (Me 2 Phen) ligand, were examined for in vitro fish DNA (FS-DNA)/ bovine serum albumin (BSA) interactions, DNA-cleavage, anticancer and antibacterial activities. Multi-spectrophotometric techniques and computational calculations were used for the interaction studies of the BSA and FS-DNA with the Y-complex. Absorption and fluorescence spectroscopy methods were used to define thermodynamic parameters, the binding constants (K b), and the probable binding mechanism. Also, the DFT (density functional theory) study and molecular docking calculation of the Y-complex were done. Besides, the nanocarriers of Y-complex (lipid nanoencapsulation (LNEP) and the starch nanoencapsulation (SNEP)), as active anticancer candidates, were prepared. Finally, DNA-cleavage, anticancer, and antibacterial activities of this complex were investigated. The absorption and fluorescence measurements were exhibited that the Y-complex has a high binding affinity to FS-DNA and BSA through a static mechanism. The negative thermodynamic parameter values for both DNA/BSA binding were confirmed that the hydrogen bonds and van der Waals forces played an essential role in the spontaneous bonding procedure. The site marker competitive studies for BSA confirmed that the Y-complex bonds to the sub-domain IB of protein (site III) on BSA, which was entirely agreement by docking calculation. The complex has displayed efficient DNA cleavage, antifungal and antibacterial activities. The anticancer activity of the Y-complex and its starch/lipid nano-encapsulated was carried out in cancer cell lines, which exposed considerably high activity. Thus, Y-complex can be transported professionally through BSA in the blood and bonds in the groove of DNA. Base on biological applications of the Y-complex, it can be concluded that this complex and its nanocarriers can suggest as novel anticancer and antibacterial candidates. [ABSTRACT FROM AUTHOR]

The advantages of polyaniline for application in new generation solar cells include its cost-effectiveness, environmentally friendly synthesis, remarkable stability, and the ability to modify the bandgap through the synthesis of its nanocomposites. But a challenge for its nanostructures is the limited solubility in non-toxic solvents, including water, which limits their processability in coating techniques. We overcame this challenge by synthesizing its copolymer with diphenylamine-4-sulfonate and its nanocomposite with titanium dioxide nanoparticles (TiO 2 NPs). So through a solid-state and template-free technique and using sodium diphenylamine-4-sulfonate, aniline hydrochloride salt, TiO 2 NPs, and FeCl 3 ∙6 H 2 O as an oxidant, poly(N-(sulfophenyl)aniline) nanoflowers (PSANFLs), poly [(aniline- co-N -(4-sulfophenyl) aniline] nanofibers (PAPSANFs), poly(N-(sulfophenyl)aniline) nanofibers/titanium dioxide nanoparticles (PSANFs/TiO 2 NPs), and poly (aniline- co-N -(4-sulfophenyl)aniline nanofibers/titanium dioxide nanoparticles (PAPSANFs/TiO 2 NPs) were synthesized. Characterization of the synthesized samples was carried out through field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectra, ultraviolet-visible spectra (UV-Vis), cyclic voltammetry (CV), and elemental analysis (CHNS). The FE-SEM images clearly illustrate that the synthesized samples are of nanoscale dimensions. The band gap values of 2.23 eV for PSANFs/TiO 2 NPs and 1.96 eV for PAPSANFs/TiO 2 NPs nanocomposites were determined through electrochemical calculations based on cyclic voltammetry curves, showcasing the complementary properties of n and p semiconductors. Using doctor blade method to prepare films from synthesized materials and the architectural pattern of ITO│TiO 2 NPs│semiconductor sample│Al , all hybrid solar cells are fabricated. The I-V characteristics and power conversion efficiency (PCE) of the samples were examined and discussed. The PCE values for the four samples were found to be in the range of 0.20–0.82 %. [Display omitted] ● The synthesis of homopolymer of sodium diphenylamine-4-sulfonate and its copolymer with aniline by mechanochemical method. ● The synthesis of nanocomposites of homopolymer (PSANFLs) and copolymer (PAPSANFs) with titanium dioxide nanoparticles (TiO 2 NPs). ● The first report of preparation of nanoflowers from PSANFLs and nanofibers from PAPSANFs and their nanocomposites with TiO 2 NPs. ● The first report of the hybrid solar cell (HSC) fabrication of them as ITO│TiO 2 NPs│sample│Al. ● The nanopolymers, nanocomposites, and their HSC preparation are inexpensive, simple, and environmentally sustainable. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 (eCO2RR) holds promise in mitigating atmospheric greenhouse gas levels but is hindered by low reaction kinetics, high energy barriers, and poor selectivity. To address these challenges, we developed a novel series of cost‐effective AgCu‐containing metal‐aerogel catalysts with high electrochemical surface areas (ECSA) using a top‐down reduction approach. The Ag85Cu15 aerogel, with an ECSA of 27.41 cm2, achieved a Faraday efficiency (FE%) of 89.3 % for CO production at −0.9 V vs. RHE. Increasing the Cu content to over 50 % in the aerogel matrix produced small amounts of C2H4, with a maximum FE% of 12.9 % at −1.0 V vs. RHE. To further enhance CO2 reduction efficiency, multi‐walled carbon nanotubes (CNT) were incorporated into the Ag85Cu15 alloy aerogel via a hydrothermal treatment. The highly dispersed CNTs within the aerogel matrix increased the ECSA to 57.00 cm2 by forming a well‐defined porous structure through van‐der Waals interactions, improving CO selectivity, and achieving a FE% of 98.6 % at −0.7 V vs. RHE and a partial current density of 9.6 mA/cm2 in an H‐cell. 86 % of the initial FECO% was maintained during an 18 h test with continuous electrolysis. [ABSTRACT FROM AUTHOR]

This study introduces a series of Rh–Pd bimetallic aerogels Rh 75 Pd 25 , Rh 50 Pd 50 , and Rh 25 Pd 75 as efficient electrocatalysts for ethanol electrooxidation, crucial for direct ethanol fuel cell technology. The bimetallic Rh–Pd and monometallic Rh and Pd aerogels were synthesized from RhCl 3 and PdCl 2 as starting materials and sodium borohydride as the reducing agent. A combination of X-ray photoelectron spectroscopy, elemental mapping, and electron microscopy studies of the bimetallic aerogels enable compositional analysis of the materials and provide insight into the porous 3D nanoarchitecture. Importantly, the material performs efficiently as an electrocatalyst on glassy carbon electrodes for the oxidation of ethanol under basic conditions (1.0 M KOH) at onset potentials ranging from −0.59 to −0.64 V (vs. Hg/HgO). Importantly, these materials exhibit high peak current densities of 216 mA/cm2 for the Rh-rich Rh 75 Pd 25 to 536 mA/cm2 for Rh 25 Pd 75 , which are significantly higher than reported peak current densities for other Pd-containing electrocatalysts. The 1H and 13C NMR techniques were used to evaluate products for ethanol electrooxidation, with the results indicating selectivity for acetic acid. This demonstrates an enhanced catalytic activity, selectivity to acetic acid vs. CO 2 , representing a significant step in advancing DEFCs and their broader application in sustainable energy technologies. [Display omitted] • Synthesis different Rh–Pd bimetallic aerogels Rh 75 Pd 25 , Rh 50 Pd 50 , and Rh 25 Pd 75. • Highly efficient electrocatalysts for ethanol electrooxidation. • Significant enhancements in catalytic activity to 536 mA/Cm2. • Bimetallic Rh–Pd aerogels selectively convert ethanol to acetic acid. [ABSTRACT FROM AUTHOR]

• Ferrocene-conjugated α-synuclein peptides were synthesized. • Square-wave voltammetry was applied to study the interaction between peptides and copper(II) ions. • The binding of copper(II) induced the folding of peptides increasing the ferrocene oxidation signal. • The interaction of zinc(II) with peptides did not cause a folding process on surfaces. • The binding of pyrroloquinoline quinone with peptides suppressed the folding process in the presence of copper(II) ions. The structure and aggregation states of alpha-synuclein (α-syn) have been shown to have a connection to the pathological development of Parkinson's disease (PD). Computational modeling studies have indicated that α-syn proteins misfold in the presence of biometals such as copper, iron and zinc, resulting in down-stream off-pathway oligomerization. If the early folding processes can be prevented, subsequent neurotoxicity due to the production of reactive oxygen species induced by the formation of α-syn-Cu(II) complexes can be suppressed. However, experimental data are lacking to support this hypothesis and many traditional approaches lack speed and sample volume efficiency. Through the application of an aptamer-like folding/unfolding strategy on an electrochemical platform, these challenges can be resolved. By exploiting the effect of spatial distance between the redox probe and electrode surface, a biosensor capable of monitoring the structural changes of α-syn peptides was constructed. Ferrocene-conjugated α-syn peptides (Fc-PEP) were immobilized on gold surfaces via gold-sulfur bond. Square-wave voltammetry (SWV) was used to monitor the Fc oxidation signal in the presence and absence of Cu(II). Full surface characterization studies were performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed that Fc-PEPs folded in the presence of Cu(II), and this behaviour could be reversed with the addition of EDTA. The biosensor was able to demonstrate distinguishable current responses between the effects of Cu(II) and Zn(II) on the folding of Fc-PEPs. Finally, in the presence of a well-described antioxidant and amyloid inhibitor, pyrroloquinoline quinone (PQQ), the current responses remained the same, indicating the strong interaction between PQQ and Fc-PEPs that suppressed the folding process. Our preliminary results demonstrated that an aptamer-like electrochemical approach has a promising potential for developing a platform toward screening the antioxidant and amyloid inhibitor molecules targeting Cu(II)-induced folding of α-syn in PD. [ABSTRACT FROM AUTHOR]

In this proof-of-concept study, a nanocomposite of poly(m-aminobenzodioxol) with Fe 3 O 4 magnetic nanorods (PABD - Fe 3 O 4 NRs) was synthesized using a one-pot synthesis. The nanocomposite was characterized using transmission electron microscopy (TEM), environmental scanning electron microscopy (ESEM), and Fourier-transform infrared spectroscopy (FT-IR), which all displayed successful synthesis. The PABD - Fe 3 O 4 NRs were then incorporated within a graphite-implanted polyacrylamide (PAA-G) hydrogel matrix to develop an innovative nanocomposite-polymer solar cell. The additional Fe3+ was then used to form a metal thiocyanate complex, [FeSCN]2+, within the pores of the hydrogel. To the best of our knowledge, this study is the first to report the use of a conductive hydrogel nanocomposite for the encapsulation of the active layer within a hybrid solar cell. The incorporation of this material as a single layer enabled storage of the [FeSCN]2+ solution as well as increased the formation of interconnected channels for faster electron transfer and diminished charge transfer resistance, and therefore, significantly enhanced the overall efficiency of the solar cell. Under simulated solar irradiation, the final FTO│TiO 2 / PAA-G-PABD-Fe 3 O 4 NRs gel [FeSCN]2+ │Al solar cell demonstrated a power conversion efficiency (PCE or η) of 6.08% and a significant enhancement of 2100% in comparison with the solar cells fabricated with PABD-Fe 3 O 4 NRs in the absence of the PAA-G and [FeSCN]2+ complex. Our preliminary results exhibited high thermal stability and displayed superior photovoltaic properties when compared to other similar solar cells in literature. We envisage that the synthesis of hydrogel nanocomposites using various nanomaterials will significantly enhance the development of high-efficiency hybrid solar cells. [Display omitted] [ABSTRACT FROM AUTHOR]

The derivatives of polyaniline have obtained remarkable attention due to their electronic applications in the field of nanomaterials. This work considers the electronic, structural, and photovoltaic properties of nanocomposites (POT/WO3NPs) synthesized with three different ratios of poly(o-toluidine) and WO3 nanoparticles [a-c (molWO3/molmonomer) 100 = 60, 65, 70%] using a template-free method and a basic mechanochemical reaction in solid-state. The nanocomposites are analyzed and characterized by various spectroscopy methods. The prepared nanocomposites have core-shell morphology. The results of the band gap assessed via cyclic voltammetry and UV-vis specified that the forbidden band gap for (POT/WO3NPs) nanocomposite b [(molWO3/molmonomer) 100 = 65%] are about 1.03 and 1.5-1.9 eV, respectively. The J-V analysis and power conversion efficiency of the fabricated devices FTO|TiO2NPs|POT|Al and FTO|TiO2NPs|POT/WO3NPs (a-c) |Al single-layer solar cells are performed and discussed. The photovoltaic energy conversion efficiency (PCE) of the two devices are 0.18% and in average, 0.57%, respectively. The data show both indirect and direct transitions are observed for the WO3NPs, POT, and POT/WO3NP (b). This investigation demonstrates that the morphology and architecture of nanocomposites (POT/WO3NPs) can be helpful in improving solar cell performance. [ABSTRACT FROM AUTHOR]

• DNA and protein (BSA) binding were comparatively analyzed by experimental and theoretical methods. • The theoretical results kept in good agreement with experimental results. • Tb-complex showed considerable DNA cleavage and antimicrobial activity. • Anti-cancer activity of the parent and nano-encapsulated terbium(III) complex was determined on in vitro assays. • The lipid nanoencapsulated (LNEP) and the starch nanoencapsulated (SNEP) have a potential for use as drug delivery systems. There is a crucial need for finding and developing new compounds as the anticancer and antimicrobial agents with better activity, specific target, and less toxic side effects. Base on the potential anticancer properties of lanthanide complexes, in the paper, the biological applications of terbium (Tb) complex, containing 2,9-dimethyl- 1,10-phenanthroline (Me 2 Phen) such as anticancer, antimicrobial, DNA cleavage ability, the interaction with FS-DNA (Fish-Salmon DNA) and BSA (Bovine Serum Albumin) was examined. The interaction of Tb-complex with BSA and DNA was studied by emission spectroscopy, absorption titration, viscosity measurement, CD spectroscopy, competitive experiments, and docking calculation. Also, the ability of this complex to cleave DNA was reported by gel electrophoresis. Tb-complex was concurrently screened for its antibacterial activities by different methods. Besides, the nanocarriers of Tb-complex (lipid nanoencapsulation (LNEP) and the starch nanoencapsulation (SNEP)), as active anticancer candidates, were prepared. MTT technique was applied to measure the antitumor properties of these compounds on human cancer cell lines. The experimental and docking results suggest significant binding between DNA as well as BSA with terbium-complex. Besides, groove binding plays the main role in the binding of this compound with DNA and BSA. The competitive experiment with hemin demonstrated that the terbium complex was bound at site III of BSA, which was confirmed by the docking study. Also, Tb-complex was concurrently screened for its DNA cleavage, antimicrobial, and anticancer activities. The anticancer properties of LNEP and SNEP are more than the terbium compound. Tb-complex can bond to DNA/BSA with high binding affinity. Base on biological applications of Tb-complex, it can be concluded that this complex and its nanocarriers can suggest as novel anticancer, antimicrobial candidates. [ABSTRACT FROM AUTHOR]

In this proof-of-concept study, a thiol-functionalized sol-gel-based carbon ceramic electrode (CCE) was developed. This CCE was further modified by immobilizing gold nanoparticles (AuNP) in the thiol-functionalized ceramic matrix as well as incorporating multi-walled carbon nanotubes (MWCNT) within the pores of this ceramic sol-gel. The proposed electrode (MWCNT-AuNP-CCE) was used for the simultaneous determination of purine derivatives, uric acid (UA), xanthine (XA) and caffeine (CA). The simultaneous detection of these compounds is essential because these purine derivatives often coexist in real samples. Moreover, since these analytes have the capacity to interchange structures, developing a simultaneous detector is important. This electrode was successfully characterized using environmental scanning electron microscopy (ESEM) with secondary and back scattering electron detectors, energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and Fourier-transform infrared (FT-IR) spectroscopy. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were performed in phosphate buffer solution (0.1 M PBS, pH 6) at a potential window of 0.2 to 1.1 V (vs. Ag/AgCl). The proposed modified electrode (MWCNT-AuNP-CCE) displayed three well-defined, stable and continuous oxidation peaks at 0.3, 0.7 and 1.0 V for UA, XA, and CA, respectively. The resulting catalytic current at the surfaces showed a linear dependence to the concentrations of UA, XA and CA for up to 225, 225 and 1500 μM, respectively. The limit of detection was determined to be 50, 63 and 354 nM for UA, XA and CA, respectively. The analytical performance of MWCNT-AuNP-CCE was challenged with real samples such as human serum and urine with recoveries ranging between 98.1 and 102.6%. Moreover, the selectivity of sensor was further challenged with very similar purine molecules, theobromine and theophylline, which contain one less methyl group than CA. Overall, MWCNT-AuNP-CCE exhibited a promising platform for the future development of sensitive electrochemical sensors for the detection of purine derivatives in real samples. • A novel thiol functionalized carbon ceramic electrode modified with nanomaterials was developed. • Simultaneous electrochemical determination of purine derivatives (uric acid, xanthine and caffeine) was achieved. • The selectivity of sensor was challenged with theobromine and theophylline. • Real sample measurements were completed in human urine and serum. [ABSTRACT FROM AUTHOR]

The synthesis of a novel nanocomposite that contains ferricyanide-doped chitosan and multi-walled carbon nanotubes (FC/Chi-MWCNTs) is reported here for the first time, to the best of our knowledge. A graphite paste electrode (GPE) with the incorporation of FC/Chi-MWCNT nanocomposite was fabricated for the simultaneous electrochemical determination of six redox-active biomolecules; ascorbic acid (AA), dopamine (DA), uric acid (UA), tryptophan (Trp), xanthine (XA) and caffeine (CA). The differential pulse voltammetric measurements were performed in 0.10 M phosphate buffer solution at pH 4.0. The MGPE displayed a strong, stable and continuous six well-separated oxidation peaks towards electrooxidation at potentials 0.15, 0.30, 0.45, 0.75, 0.85, and 1.34 V for AA, DA, UA, Trp, XA and CA, respectively. The calibration curves were linear up to 2056.8, 94.1, 193.7, 198.9, 191.3, 2.4 μM with a limit of detection of 5.3 μM, 1.1, 2.7, 3.7, 7.3 nM, 2.2 μM for AA, DA, UA, Trp, XA and CA, respectively. The analytical performance of the FC/Chi-MWCNT-modified electrodes has been evaluated using human serum and urine samples with recoveries of 94.25–115%. Thus, we concluded that the synthesized FC/Chi-MWCNT-nanocomposites provided a promising electrochemical platform for development into routine clinical applications. • Nanocomposite of ferricyanide-doped chitosan and multi-walled carbon nanotubes was synthesized. • Nanocomposite was incorporated into a graphite paste electrode. • Simultaneous electrochemical detection of six biomolecules was achieved. • Real sample applications were performed using human serum and urine. [ABSTRACT FROM AUTHOR]

Two dimensional single-crystal hexagonal gold nanosheets (SCHGNSs) were prepared by microwave heating of a solution of HAuCl4 in an ionic liquid. The SCHGNSs were characterized by field emission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, atomic force microscopy and electrochemical impedance spectroscopy. The SCHGNSs were then used to modify a graphite paste electrode for voltammetric determination of the hypertension drug captopril (CAP). The modified electrode showed a well-defined oxidation peak (at 0.41 V vs. Ag/AgCl) at pH 7.0 using differential pulse voltammetry. Under the optimum conditions, the response is linear in the 2-400 nM and 4.0-50 μM CAP concentration range, and the detection limit (at S/N = 3) is 0.3 nM. The sensor was successfully applied to the determination of CAP in pharmaceutical tablets and in spiked urine.Schematic presentation of the preparation of single crystal hexagonal gold nanosheets and their use to modify a carbon paste electrode for ultra-trace voltammetric determination of the drug captopril [ABSTRACT FROM AUTHOR]

Highly dispersed palladium nanoparticles that are successfully decorated on the charcoal activated carbon by a rapid and simple improved polyol method in Ethylene Glycol (EG) media in the presence of ethanolic sodium hydroxide, without any protection by capping agent, is proposed for the first time in this paper. Along this process, H 2 PdCl 4 in ethylene glycol media can be reduced to metallic palladium at 40°C in the presence of alcoholic sodium hydroxide. Therefore, it can be claimed that ethanolic sodium hydroxide is behaving like a mild reducing agent in the EG media. Pd/C catalysts are also synthesized using improved and traditional methods for comparison. Catalysts synthesized in two different ways were characterized by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results illustrated that Pd/C synthesized using the improved polyol method had better dispersity and its diameter was equal to 8–10 nm which was lower compared to the conventional polyol method. The electrocatalytic performance of both Pd/C catalysts synthesized by two methods was investigated by cyclic voltammetry and chronoamperometry in the solution of 1.0 M EtOH +1.0 M NaOH at room temperature. The results showed that the Pd/C catalyst synthesized by the improved method had a significantly enhanced the activity and durability for Ethanol Oxidation Reaction (EOR) that can be related to the good dispersity of Palladium nanoparticles over support due to the improved polyol method. Image 1 • Polyol method was improved by adding alcoholic NaOH to reaction mixture. • The proposed polyol method caused a significant reduction in temperature and reaction time. • Pd/C catalyst prepared by improved polyol method shows higher catalytic activity. [ABSTRACT FROM AUTHOR]

In this proof-of-concept study, a microfluidic flow injection analysis (FIA) system was developed using multi-walled carbon nanotube-modified screen-printed carbon electrodes (CNTSPEs) that were modified with copper nanoparticles (CuNPs) following the electrodeposition of the diazonium salt of 4-aminothiophenol to form 4-thiophenol-conjugated CuNPs (CuNPs-CNTSPE). Transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) were used to characterize the size of CuNPs, morphology and elemental analysis of CuNPs-CNTSPE, respectively. Using electrochemical impedance spectroscopy (EIS), the charge-transfer resistance (R ct) of CuNPs-CNTSPE was found to be 20-fold lower than that of CNTSPE. The CuNPs-CNTSPE displayed an oxidation peak for dopamine at −0.08 V which is ∼80 mV lower than the one detected using CNTSPE. The modified electrode was used in microfluidic flow injection analysis and offline systems for sensitive detection of dopamine (DA). The pH, flow rate, loop volume, concentration, and type of surfactant were all optimized for on-chip detection. Under the optimal conditions, using phosphate electrolyte solution (pH 6) containing 0.05% (w/v) Tween 20® as the carrier at a flow rate of 0.6 mL min−1 and a loop volume of 50 μL, the calibration curve was linear from 1.5 to 500 nM with a limit of detection of 0.33 nM. This technique was used for the successful detection of DA in real samples with recovery ranging from 96.5% to 103.8%. The microfluidic FIA system described here has the potential to be used as an electrochemical point-of-care device for rapid DA detection with high sensitivity and reproducibility. [Display omitted] • Screen-printed electrodes were modified with copper nanoparticles using diazonium chemistry. • Microfluidic flow injection analysis system was developed for the chronoamperometric determination of dopamine. • Ultrasensitive detection of dopamine was achieved in real samples. [ABSTRACT FROM AUTHOR]

In this study, ceramic membranes were fabricated using commercially available ceramic powder, native Kalporgan's soil and acid-leached native Kalporgan's soil, which were used in MFCs as the membrane, and the performances were compared. The ceramic powder based membrane was applied as an appropriate reference. By leaching the native soil using phosphoric acid, the compounds such as iron, calcium, and magnesium were reduced that is melting during the sintering in a furnace before 900 °C and produced liquid phase was placed within SiO 2 networks at the membrane structure, which is referred to sintering phenomena. The porosity of 49.58 ± 0.52% was obtained for the leached membrane while 19.22 ± 0.50% was achieved for non-leached membrane indicating that the leaching process increased the porosity of the membrane significantly and based on the SEM images it reduced the average size of cavities (3.5–0.08 μm). The internal resistance was significantly decreased from 977.36 to 52.81 Ω, and the power density increased remarkably 42 times from 0.48 to 20.18 W/m3, and the maximum current density climbed by 15 times from 102 to 1535 mA/m2. The results of this study revealed that the fabricated ceramic membrane can be an excellent candidate as proton exchange membrane. • Bioelectricity increased in MFC with membrane using acid leached native soil. • Leaching the native soil significantly decreased the internal resistance of MFC. • The Ohmic resistance of ion exchange in membrane eliminated approximately. • An ideal super capacitor was achieved in leached native soil. [ABSTRACT FROM AUTHOR]