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In recent years, there has been considerable attention in unique materials in the field of nanotechnology. Magnetic nanoparticles (MNPs) relate to the family of nanotechnology with an impression in areas of nanomedicine, biosensing, and analytical chemistry. MNPs that exhibit super magnetic and catalytic features have been extensively recognized as one of the greatest talented nanoagents used in various fields. Although many articles have been published to explain the synthesis of MNPs, a small number of useful methods are generally used for their separation and isolation. Because of their inapproachable physical and chemical features, MNPs are interesting applicants for biomedical usages and analytical isolations. In this chapter, we describe the isolation methods that have been primarily exploited for this aim. It is the usage of a practical magnetics flux or field gradients such as magnetic field-flow fractionation and high-gradient magnetic separation that allows isolations for MNPs. Extra methods have been discovered for employing particles in microfluidic channels or mesoporous membranes. Additional improvement of these methods and novel experimental techniques for isolation and examination of nanoparticles with magnetic features is essential to permit the valuable exploit of these, chiefly in the medical fields.

A colorimetric paper-based sensor is proposed for the rapid monitoring of six major organophosphate and carbamate pesticides. The assay was constructed by dropping gold and silver nanoparticles on the hydrophilic zones of a paper substrate. The nanoparticles were modified by L-arginine, quercetin, and polyglutamic acid. The mechanism of sensing is based on the interaction between the pesticide and the nanoparticles. The color of nanoparticles changed during the interactions. A digital camera recorded these changes. The assay provided a unique response for each studied pesticide. This method can determine six individual pesticides including carbaryl, paraoxon, parathion, malathion, diazinon, and chlorpyrifos. The limit of detection for these pesticides were 29.0, 22.0, 32.0, 17.0, 45.0, and 36.0 ng mL−1, respectively. The assay was applied to simultaneously determine the six studied pesticides in a mixture using the partial least square method (PLS). The root mean square errors of prediction were 11, 8.7, 9.2, 10, 12, and 11 for carbaryl, paraoxon, parathion, malathion, diazinon, and chlorpyrifos, respectively. The paper-based device can differentiate two types of studied pesticide (organophosphate and carbamate) as well as two types of organophosphate structures (oxon and thion). Furthermore, this sensor showed high selectivity to the pesticides in the presence of other potential species (e.g., metal ions, anions, amino acids, sugar, and vitamins). This assay is capable of determining the pesticide compounds in tap water, apple juice, and rice samples. Graphical abstract

This study introduces an applicable colorimetric sensor array for the detection of pesticides in the vapor phase. The array consisted of six metal nanoparticles spotted on the piece of filter paper. 3D-origami pattern was used for the fabrication of a paper-based sensor to decrease the effect of the nanoparticles leaching after exposure to analytes. Exposure to pesticide aerosols caused changes in the color of the array due to the aggregation of nanoparticles. These changes provided selective responses to thion pesticides such as malathion, parathion, chlorpyrifos, and diazinon. The sensing assay could also differentiate between aliphatic and aromatic thions and discriminate amine-containing compounds from the other studied analytes. These finding results are clearly confirmed by both visual detection and multivariate statistical methods. The proposed sensor was successfully developed for the quantitative measurement of pesticide aerosols at a very low concentration. The limit of detection of this method determined for malathion, parathion, chlorpyrifos and diazinon were 58.0, 103.0, 81.0 and 117.0, respectively. Moreover, the array could be employed to simultaneously analyze four studied pesticides. The statistcal results confirmed that the method has high performance for concurrent detection of thions as a major air pollutant without the interference of other species.

This work presents an effective strategy for the well-oriented immobilization of antibodies in which boronic acid is directly attached to the surface and with no need of the long and flexible spacer. A magnetic graphene nanoribbon-boronic-acid-based immunosensor was developed and tested for the impedimetric detection of lymphoma cancer cells, a blood cancer biomarker. Magnetic graphene nanoribbons (MGNRs) were modified with boronic acid (BA) to create a supporting matrix that is utilized by immobilizing anti-CD20 antibodies with good orientation. The prepared biosensing layer (MGNR/BA/Ab) with well-oriented antibodies was premixed into whole blood samples to interact with lymphoma cancer cell receptors. In the presence of target cell receptors, an immunocomplex was formed between anti-CD20 antibodies and lymphoma cancer cell receptors. Then, the biosensing layer was magnetically collected on a screen-printed carbon electrode (SPCE) and placed in a homemade electrochemical cell configuration to measure impedimetric signals. The fabrication steps of the immunosensor were characterized by various techniques, such as resonance light scattering, fluorescence, electrochemical impedance spectroscopy, and cyclic voltammetry. The assay is highly sensitive: the calculated limit of detection of lymphoma cancer cells was as low as 38 cells/mL, and the detection was linear from 100 to 1 000 000 cells/mL. The specificity of the immunosensor is also very high, and there is no interference effect with several potential interferents, such as the breast cancer (MCF-7), human embryonic kidney (HEK293), and leukemia (HL-60 and KCL-22) cell lines. The performance of the immunosensor for lymphoma cancer cells in clinical blood samples is consistent with that of commercial flow cytometric assays.

In this paper, a novel enzymeless electrochemical sensor with high sensitivity was constructed based on TiO2 functionalized graphene oxide@UiO-66 (TGO@UiO-66) for simultaneous detection of paraoxon and chlorpyrifos. TGO@UiO-66 for electrode modification possesses good conductivity and a distinctive structure, which promotes the electron transfer rate and improves the efficiency of electrochemical sensors. In this work, a TGO@UiO-66 modified glassy carbon electrode (TGO@UiO-66/GCE) was used for simultaneous determination of paraoxon and chlorpyrifos. The square wave voltammogram of TGO@UiO-66/GCE in the presence of paraoxon and chlorpyrifos showed two characteristic cathodic peaks at −0.45 and −1.3 V (vs. Ag/AgCl). Also, excellent electrochemical characteristics of the proposed sensor were evidenced by impedance and cyclic voltammetry studies in a Fe(CN)64−/3− solution. Different experimental parameters such as the type of electrolyte, pH of the electrolyte, and scan rate were optimized, and calibration curves were plotted under the optimal conditions. The designed sensor exhibited low detection limits of 0.2 and 1.0 nM within the linear ranges of 1.0–100.0 nM and 5.0–300.0 nM for paraoxon and chlorpyrifos, respectively. The developed sensor was successfully applied to pesticide residue monitoring in vegetable and water samples.

We assessed possible changes in the levels of some trace elements among nuclear medicine staff. This study was carried out on 30 nuclear medicine staff and 10 individuals as a control group. After the blood samples were collected, serum levels of trace elements were measured using atomic absorption spectroscopy (AAS). Mean Zn levels in the control group (89.75 ± 17.35 µmol/l) were significantly (p = 0.002) higher than in the exposed group (70.91 ± 14.46 µmol/l). Increased duration of exposure was significantly associated with reduced zinc levels (p = 0.005). Furthermore, the 5-year average dose received was adversely and significantly correlated with zinc concentrations (p = 0.019). No significant difference was observed in the Cu level between control group (93.85 ± 25.33 µmol/l) and staff worker group (85.6 ± 21.66 µmol/l) (p = 0.32). A positive significant correlation was observed between exposure time and reduced Cu levels (p = 0.05). No difference was found in mean Mn and Se levels between both groups according to exposure time. Declined Zn and Cu levels may be considered as one of the possible mechanisms of oxidative damages induced by gammas rays. Therefore, an antioxidant treatment could be recommended for people who work in medical radiation centers.

Introduction: Although some countries have set up predetermined programs and specialized teams to deal with hazardous materials (Hazmat) induced events, in other countries including Iran there are many weaknesses in this regard. Objective: We aimed to develop the necessary indicators for the formation of teams to deal with Hazmat accidents in the health system based on existing standards and resources as well as the indigenous conditions of Iran. Methods: This cross-sectional study was carried out in two stages from 2018 to 2020. In the first stage, the literature review was performed and the current guidelines, standards, and models presented in other countries were reviewed and related items were extracted. In the second stage, semi-structured and purposeful interviews by managers and physicians specialized in Hazmat incidents working in Iran, were conducted. The interviews were recorded and later the recordings were transcribed and simultaneously the categorizing and coding of the interviews were performed. Results: In the first stage, searching through the available resources for the present study identified 12 published references through which 10 indicators to develop a Hazmat team were ultimately extracted. In the second stage, a total of 10 interviews were conducted and data saturation occurred. Based on the results of the content analysis for the main indicators of designing and developing teams, 8 categories and 19 sub-categories were developed. Conclusions: The results of this project outline 10 key indicators for designing a Hazmat team of the health system. Emergency Response Program, Personal Protective Equipment Program, Medical Surveillance Program, Training of Hazmat Team Members, Hazmat Team’s Structure and Response, Hazmat Team Dispatch, Team’s Position in Incident Command System, Hazmat Team Equipment, Hazmat Team certification and Maintenance of Certificate is a key element for team formation.

A high-performance sensing layer based on dual-template molecularly imprinted polymer (DMIP) was fabricated and successfully applied for one-by-one detection of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) as lung cancer biomarkers. The plastic antibodies of AFP and CEA were created into the electropolymerized polypyrrole (PPy) on a fluorine-doped tin oxide (FTO) electrode. Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) tests were performed to pursue the formation and characterization of the sensing layer. Methyl orange (MO) increased the conductivity of PPy and induced the formation of MO doped PPy (PPy-MO) rectangular-shaped nanotubes. Using impedimetric detection, the rebinding of the template antigens was evaluated, the charge transfer resistance increased as the concentration of AFP and CEA increased. The linear dynamic ranges of 5-10

A new sensing layer composed of BSA templated Au-Pt bimetallic nanoclusters (Au-Pt@BSA/GCE) and graphene nanoribbons (GNRs) was employed for the rapid, selective and sensitive determination of diazinon as an enzyme-less electrochemical sensor. The UV–vis absorption spectroscopy, fluorescence spectroscopy, transmission electronic microscopy, X-ray diffraction and Fourier transform infrared techniques were used to investigate the size, morphology, and structure of the synthesized nanocomposite. Additionally, the electrochemical properties of the sensor were investigated by cyclic voltammetry, square wave anodic stripping voltammetry and electrochemical impedance spectroscopy. The results showed that Au-Pt@BSA-GNRs/GCE significantly catalyzes the oxidation and reduction of diazinon during electrochemical detection. The linear ranges of diazinon were between 0.01–10.0 and 10.0–170 μM, with a detection limit of 0.002 μM. The selectivity, stability, and reproducibility of Au-Pt@BSA-GNRs/GCE were studied, and obtained data indicates the great potential of the sensor as an alternative to enzyme inhibition-based biosensors for the determination of diazinon. The constructed electrode was employed for the determination of diazinon in some real samples with complex matrices such as soil, diverse water, fruit, and vegetables. The results indicate the excellent capability of the method for the detection of diazinon in real samples in comparison with the standard method.

This work demonstrates the development of a gold screen-printed electrode (Au-SPE)-based biosensor modified with a molecularly imprinted polymer and amplified using antibody-conjugated nano-liposomes. The developed biosensor was utilized for dual determination of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) as cancer biomarkers. To prepare this biosensor, Au-SPE was modified with 3,3′-dithiodipropionic acid di(N-hydroxysuccinimide ester) via self-assembly method and then the target proteins (EGFR and VEGF) were covalently attached to the modified SPE. To synthesize the molecularly imprinted polymer, monomers of acrylamide and N,N′-methylenebis(acrylamide) were polymerized around the EGFR and VEGF templates, and to characterize the prepared biosensor, electrochemical impedance spectroscopy was used for analyses of surface changes in the engineered electrodes. To produce reliable electrochemical signals, nano-liposomes which were loaded with Cd(II) and Cu(II) cations and decorated with antibodies specific for EGFR and VEGF were used as an efficient tool for detection of target biomarkers. In the analysis step, potentiometric striping analysis (PSA), as an electrochemical technique, was utilized for sensitive determination of these cations. The limits of detection (LODs) of EGFR and VEGF analyses were found to be 0.01 and 0.005 pg mL−1 with the linear dynamic ranges (LDRs) of 0.05–50000 and 0.01–7000 pg mL−1, respectively. Moreover, the proposed biosensor was successfully used for sensitive, reproducible, and specific detection of EGFR and VEGF in real samples. Due to the SPE nature of the developed biosensor, we envision that this sensing tool has capability of being integrated with lab-on-a-chip (LOC), microfluidics, and micro total analysis systems.

A novel, sensitive, and selective electrochemical sensor has been fabricated for the determination of 1-naphthyl methylcarbamate (carbaryl) as an important pesticide. Three-dimensional graphene (3DG) was synthesized by using thiourea as the crosslinking agent that simultaneously caused impregnation of sulfur and nitrogen functional groups onto the graphene. Graphene doped with S and N atoms was modified by gold nanoparticles. The obtained 3DG-Au nanocomposite was used for the determination of carbaryl by differential pulse voltammetry. Different experimental parameters such as pH, type of electrolyte, accumulation time, and accumulation potential were optimized. Under optimal conditions, a linear response was achieved in the range of 0.004–0.3 μM of carbaryl with a detection limit of 0.0012 μM (S/N = 3). The sensor demonstrated suitable selectivity, stability, and reproducibility through its successful application for the determination of carbaryl in fruit, vegetable, and water samples with good recoveries.

For the first time, a sensitive and selective method for determination of docetaxel (as an anti-cancer drug) at gold nanoparticle-multiwall carbon nanotubes/glassy carbon electrode (Au-MWCNTs/GCE) was suggested using cyclic voltammetry and differential pulse anodic stripping voltammetry (DPASV) method. After the construction of the electrochemical sensor and optimization of the effective parameters such as pH, accumulation time, and potential, the sensor was applied for the determination of docetaxel in the range of 0.3–3.3 μmol L−1. The results show that Au-MWCNTs significantly catalyzed the redox reaction of docetaxel during electrochemical detection. The limit of detection was estimated to be 90 nmol L−1 based on 3Sb/m. The performed studies showed that Au-MWCNTs/GCE has a good selectivity, sensitivity, and reproducibility. This sensor was used to determine the docetaxel in real samples (human urine and human serum), and the obtained data illustrate that fabricated electrochemical sensor is promising for use in routine analytical applications.

Developing sensitive strategies to detect the biomarkers is responsible for early detection of a genetic disorder and cancer-related biomarkers. Herein, a rational design of high catalytic activity of artificial enzyme mimics with enhancing the robustness of functional nanozymes has been introduced to detect PSA as a model target. Using a separation/enrichment tool of capture antibody (cAb1)-modified magnetic nanoparticles (MNPs/cAb1), signal amplifier luminol (LUM)-loaded graphitic carbon nitride nanosheets (C3N4 NS)-encapsulated NH2-MIL(53)-Fe (NMF) (C3N4@LUM/NMF)) to label signal antibody (Ab2) as a specific targeting and a supporting platform of a nanoporous gold electrode (NPGE) with high-efficiency electron acceleration, a cascade signal amplification strategy has been achieved. In addition, the nanoscale proximity effect of confined LUM within the C3N4@NMF nanozyme and synergistically enhanced catalytic activity causes significantly to promote the electrochemiluminescence (ECL) of LUM owing to minimize the decomposition of highly active intermediates of •OH-generating reaction of C3N4@NMF nanozymes from H2O2. Taking the advantages of multiple-amplification, the present strategy shows PSA detection in dynamic range of 0.1 pg mL−1-60 ng mL−1 with 0.02 pg mL−1 limit of detection. This ECL-based nanozyme opens a new horizon for high sensitive targeted bioanalysis with functional nanomaterial design.

A sensitive electrochemiluminescence (ECL) aptasensor for aflatoxin M1 (AFM1) detection by a closed bipolar electrode (BPE) array has been introduced. The thiolated AFM1 aptamer was immobilized on gold nanoparticle-coated magnetic Fe3O4 nanoparticles (Apt-GMNPs). Luminol-functionalized silver nanoparticle-decorated graphene oxide (GO-L-AgNPs) participates in π-π interactions with the unpaired bases of the immobilized aptamer (Apt-GMNPs-GO-L-AgNPs). After the Apt-GMNPs-GO-L-AgNPs were introduced to a gold anodic BPE array, the individual electrodes were subjected to different concentrations of AFM1. Upon the interaction of AFM1 with the aptamers, the GO-L-AgNPs detach from the aptamer; the resulting ECL of luminol and H2O2 at the anodic poles is monitored using a photomultiplier tube (PMT) or smartphone, and the images are analyzed using ImageJ software. This process triggers thionine reduction at the cathodic poles. Under the optimal conditions obtained by a face-centered central composite design (FCCD), the PMT-based detection of the BPE-ECL aptasensor exhibit a linear response over a wide dynamic range from 5 to 150ngmL-1, with a detection limit of 0.01ngmL-1. Additionally, smartphone-based detection shows a linear relationship between the ECL image gray value and the logarithmic concentration of the AFM1 target over a range of 10-200ngmL-1, with a detection limit of 0.05ngmL-1. Furthermore, the BPE-ECL aptasensor was successfully used to detect AFM1 in milk complex media without any serious interferences with reliable reproducibility (average relative standard deviation (RSD = 2.3%)). This smartphone-based detection opens a new horizon for bioanalysis that does not require a trained technician to operate and is a promising technology for point-of-care testing.

In this study, a new strategy for the preparation of a modified glassy carbon electrode (GCE) based on a novel nano-sensing layer for the electrocatalytic oxidation of hydrazine was suggest...

A smartphone-based microfluidic platform was developed for point-of-care (POC) detection using surface plasmon resonance (SPR) of gold nanoparticles (GNPs). The simultaneous colorimetric detection of trace arsenic and mercury ions (As3+ and Hg2+) was performed using a new image processing application (app). To achieve this goal, a microfluidic kit was fabricated using a polydimethylsiloxane (PDMS) substrate with the configuration of two separated sensing regions for the quantitative measurement of the color changes in GNPs to blue/gray. To fabricate the microfluidic kit, a Plexiglas mold was cut using a laser based on the model obtained from AutoCAD and Comsol outputs. The colorimetric signals originated from the formation of nanoparticle aggregates through the interaction of GNPs with dithiothreitol – 10,12-pentacosadiynoic acid (DTT-PCDA) and lysine (Lys) in the presence of As3+ and Hg2+ ions. This assembly exhibited the advantages of simplicity, low cost, and high portability along with a low volume of reagents and multiplex detection. Heavy Metals Detector (HMD), as a new app for the RGB reader, was programmed for an Android smartphone to quantify colorimetric analyses. Compared with traditional image processing, this app provided significant improvements in sensitivity, time of analysis, and simplicity because the color intensity is measured through a new normalization equation by converting RGB to an Integer system. As a simple, real-time, and portable analytical kit, the fabricated sensor could detect low concentrations of As3+ (710 to 1278 μg L−1) and Hg2+ (10.77 to 53.86 μg L−1) ions in water samples at ambient conditions.

In the present manuscript, a modified glassy carbon electrode with BSA templated Au–Ag bimetallic nanoclusters (Au–Ag@BSA/GCE) was employed for the rapid, selective and sensitive determination of methyl parathion (MP) as an enzyme-less electrochemical biosensor. The properties and morphology of the synthesized bimetallic nanoclusters were characterized by fluorescence, transmission electronic microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy techniques. Additionally, the properties of the prepared biosensors were investigated by cyclic voltammetry (CV), square wave anodic stripping voltammetry (SWASV) and electrochemical impedance spectroscopy (EIS). The results show that Au–Ag@BSA/GCE greatly catalyzed the redox reaction of MP during electrochemical detection. Under optimal conditions, the linear dynamic ranges of MP were obtained between 0.02 to 8.0 and 8.0 to 200 μmol L−1, with a detection limit of 8.2 nmol L−1. The selectivity, stability, repeatability, and reproducibility of Au–Ag@BSA/GCE were studied, and the obtained data suggest that the proposed biosensor has an excellent capacity as an alternative to enzyme inhibition-based biosensors for the determination of MP. The constructed biosensor was able to successfully electrochemically determine the presence of MP in different water, apple, vegetable, and soil samples.

A novel electrochemical sensor for sensitive determination of ampyra (Am) based on graphene nanoribbons modified by iron-platinum bimetallic nanoparticles and uric acid (SPCE/FePtGNR/UA) dropped on the screen-printed carbon electrode (SPCE) surface and magnetically captured onto an SPCE working electrode surface is reported in the present work. The modified nanocomposite and sensing layer was characterized by different techniques, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray powdered diffraction (XRD). Am determination by conventional electrochemical methods is not possible, because of its high redox overpotential. Therefore, the differential pulse voltammetry (DPV) signals of UA were used as a redox probe for indirect electrochemical determination of Am. The limit of detection (LOD) and linear concentration range were obtained as 0.028 and 0.08-9.0µmolL-1 (3Sb/m = 3), respectively. The feasibility of the proposed method was examined by the detection of Am in biological and pharmaceutical samples with satisfactory results. The constructed electrochemical sensor was applied for fast, simple and sensitive detection of Am in real environments.

In the present research, we have developed a novel label free aptasensor based on screen printed carbon electrode (SPCE) modified with three-dimensional magnetic reduced graphene oxide(3D-MRGO)/polyaniline(PA)/gold nanoparticle(AuNP) nanocomposite for impedimetric determination of cocaine. To achieve this goal, a specific thiolated cocaine aptamer was immobilized onto the surface of synthesized nanocomposite. The signaling mechanism of the proposed aptasensor was based on increase in the [Fe(CN)6]3-/4- charge transfer resistance (RCT) as an electrochemical probe in the presence of target analyte. In order to collect of 3D-MRGO/PA/AuNP/aptamer on the surface of working electrode easily, a new electrochemical cell was fabricated. The advantages of the new electrochemical cell configuration can be counted as reusing SPCE for several times, obtaining repeatable responses, reducing required volume of electrolyte and probe solution and making proposed method more user-friendly. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) were used for the characterization of synthesized nanocomposite and modified electrode surface. Under optimized condition, cocaine was determined in a linear concentration range from 0.09 to 85 nM with a detection limit of 0.029 nM by EIS. Also, in order to test applicability of the proposed aptasensor, it was applied to determine cocaine in urine and serum samples and satisfactory results were obtained.

For the first time, simultaneous voltammetric determination of two kinds of the first-line categorized anti-tuberculosis drugs including isoniazid (INZ) and ethambutol (EBL) was reported at a highly sensitive electrochemical sensor. The proposed sensor was successfully prepared based on an electroactive poly-melamine film and electrodeposited gold nanoparticles (PMel-Aunano)-modified pre-anodized glassy carbon electrode (GCE*). The morphological and electrochemical characteristics of the sensing surface (PMel-Aunano/GCE*) was well-characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The PMel-Aunano/GCE* exhibited strongly catalytic activity toward the oxidation of INZ (0.39 V potential shift) and EBL (0.29 V potential shift) in comparison with PMel/GCE* and bare GCE. Differential pulse voltammograms of INZ and EBL depicted the linear responses with their concentrations at the ranges of 0.3 to 170.0 μM and 0.5 to 150.0 μM, respectively. The detection limits for INZ and EBL were sequentially estimated as 0.08 and 0.21 μM. Furthermore, the developed electrochemical sensor was successfully implemented for the determination of INZ and EBL in real samples using standard addition method. This fabricated sensor showed to be promising for INZ and EBL detection with many desirable features including high-sensitivity, low detection limit, decrease in over-voltage, reproducible responses, and acceptable anti-interferences ability.

Background This study aimed to assess the effects of the topical application of tamoxifen on wound healing of burned skin in Wistar rats by evaluating 3 healing characteristics: fibrotic tissue thickness (FTT), scar surface area (SSA), and angiogenesis in the healed scar tissue. Methods Eighteen male Wistar rats were used in this study. A third-degree burn wound was made on the shaved animals’ back, measuring 2×2×2 cm. In the first group, a 2% tamoxifen ointment was applied to the wound twice daily for 8 weeks. The second group received a placebo ointment during the same period. The third group did not receive any treatment and served as the control group. Results The median (interquartile range=[Q1, Q3]) FTT was 1.35 (1.15, 1.62) mm, 1.00 (0.95, 1.02) mm, and 1.25 (0.8, 1.5) mm in the control, tamoxifen, and placebo groups, respectively (P=0.069). However, the FTT in the tamoxifen group was less than in the placebo and control groups. The median angiogenesis was 3.5 (3.00, 6.25), 8.00 (6.75, 9.25), and 7.00 (5.50, 8.25) vessels per high-power field for the control, tamoxifen, and placebo groups, respectively (P=0.067). However, the median angiogenesis was higher in the tamoxifen group than in the control group. No significant difference was observed in the mean SSA between the tamoxifen group and the control group (P=0.990). Conclusions Local application of tamoxifen increased angiogenesis and decreased the FTT, with no change in the SSA in burned skin areas. These effects are expected to expedite the wound healing process, reducing contracture and preventing hypertrophic scar and keloid formation.

This paper presents a novel impedimetric sensor for the sensitive determination of ampyra (Am) based on the l -Cysteine/Cu (II) modified gold electrode (Cu (II)/L-Cys/AuE). This novel sensing layer was characterized by different techniques, including atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Am determination by conventional electrochemical methods is not possible, because of its high redox overpotential. Therefore, [Fe(CN)6]3-/4- was used as a redox probe for the impedimetric determination of Am. Under the optimized conditions, the calibration curve for Am concentration was linear in the range 0.010–40.0 nM with a detection limit of 0.0028 nM. The practical applicability of the proposed sensor was examined by evaluating the detection of Am in biological fluids and pharmaceutical samples with satisfied recoveries. Therefore, the prepared sensor can hold great promise for fast, simple and sensitive detection of Am in various real samples.

In the present research, design and construction of a development potentiometric sensor based on a newly nanosensing layer for the sensitive determination of tramadol in various real samples were suggested. The proposed nanosensing layer was fabricated with the incorporation of a synthesized tramadol-imprinted polymer nanoparticles “as an efficient sensing agent” into the carbon paste matrix composed of graphite powder, decorated graphene nanosheets with silver nanoparticles, and a typically ionic liquid as the conductive pasting binder. The detection limit and the linear range of this study were found to be 2.04 × 10−9 and 3.50 × 10−9 to 1.00 × 10−2 M with a Nernstian slope of 59.85 ± 0.13 mV decade−1, respectively. The presented modified carbon paste sensor was successfully applied for the determination of tramadol in pharmaceutical and biological samples.

The synthesis of a novel nanocomposite comprised of SiO2-coated magnetic graphene oxide modified with a pyrrole-thiophene (mGO/SiO2@coPPy-Th) copolymer is reported in the present work. The nanocomposite was applied for the fast magnetic solid phase extraction (MSPE) of trace levels of copper, lead, chromium, zinc and cadmium from water and agricultural samples. The nanocomposite was prepared in three steps: (1) decoration of graphene oxide sheets with magnetite nanoparticles thorough a facile one-step chemical reaction strategy; (2) chemical grafting by a silica layer to obtain high stability in acidic solutions; and (3) surface modification by coPPy-Th via simultaneous oxidation polymerization of pyrrole and thiophene in the presence of mGO/SiO2 composite. The nanocomposite was subsequently characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD) and vibrating sample magnetometry (VSM) techniques. Several important experimental variables that could affect MSPE performance, including the pH of the sample, sorption time, sorbent dosage, eluent type and its concentration, eluent volume and elution time, were investigated and optimized. Under optimal conditions, the limits of detection for the target heavy metals ranged from 0.15 to 0.65μgL-1. The maximum sorption capacity of the mGO/SiO2@coPPy-Th nanocomposite was 201, 230, 125, 98 and 80mgg-1 for Cu(II), Pb(II), Zn(II), Cr(III) and Cd(II), respectively. Finally, the feasibility of the proposed method was investigated for the extraction and determination of the target metals from real matrices.

A ternary nanocomposite of Fe3O4 SnO2 Gr was synthesized and characterized by scanning electron microscopy and X-ray diffraction. A novel sensing layer was constructed by incorporation of the prepared nanocomposite into carbon paste electrode (CPE) for the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Three clear and well-separated voltammetric peaks along with the remarkably increased electro-oxidation currents were obtained on the modified electrode (Fe3O4 SnO2 Gr/CPE) in differential pulse voltammetry (DPV) measurements. The linear calibration curves were obtained by plotting the peak currents against the analytes concentrations in the range of 0.1 to 23.00, 0.02 to 2.8, and 0.015 to 2.40 μM, with detection limits of 62.0, 7.1 and 5.0 nM for AA, DA, and UA, respectively. Additionally, the Fe3O4 SnO2 Gr/CPE presented a noticeable anti-interference ability, stability, and reproducibility. Also, the obtained electrode showed satisfactory results when applied for the determination of the AA, DA and UA in biological fluids and pharmaceutical samples.

A biocompatible nanocomposite including bovine serum albumin (BSA) template Cu nanoclusters (CuNCs@BSA) and single-walled carbon nanotubes (SWCNT) was synthesized to fabricate a highly sensitive electrochemical biosensor for paraoxon as a model of organophosphates. The UV–vis, fluorescence and Fourier transform infrared (FTIR) demonstrated that BSA entrapped in the nanocomposite film have been changed in its secondary structure so that it provided an enzyme like activity attributing to the high electrical conductivity of the entrapped copper nanoclusters. Also, the morphology and structure of prepared nanocomposites were investigated by transmission electronic microscopy (TEM) and scanning electron microscopy (SEM). In the prepared nanocomposite, the CuNCs@BSA found to play as a conductive holder as well as an accumulator of redox active centers on the surface of the electrode, and SWCNT improves the electrocatalytic activity along with conductivity of glassy carbon electrode (GCE) surface. The fabricated biosensor exhibited excellent sensitivity, acceptable stability, fast response, and high electrocatalytic activity toward the reduction of paraoxon. The reduction peak current vs paraoxon concentration was linear over the range 50 nM to 0.5 μM and 0.5–35 μM, with a limit of detection of 12.8 nM. Notable electrocatalytic properties of the developed electrode toward paraoxon indicated that the nanocomposite possesses a promising potential to fabricate the third generation enzyme-free electrochemical biosensors, bioelectronics and state-of-the-art biomedical devices in the future.

Adsorption processes as water purification processes have attracted more attention everywhere, from research departments to industrial sections. The first part of this chapter introduces the general principles of the adsorption processes. The next part presents more common pollution models. Then, various nanoadsorbents will be discussed. The fourth section deals with the mechanism of the adsorption, and the final section covers the conclusion of this contents. The chapter will be of excellent application to correct design of nanoadsorbents and development of water treatment process.

A novel electrochemical sensor based on the reduced graphene oxide-Cu/CuO-Ag nanocomposite modified glassy carbon electrode (rGO/Cu/CuO-Ag/GCE) has been applied for the simultaneous analysis of carbaryl and fenamiphos as two important pesticides. The electrochemical behavior of carbaryl and fenamiphos at rGO/Cu/CuO-Ag/GCE was studied by cyclic voltammetry and differential pulse voltammetry. The modified electrode exhibited two separated oxidation signals for the simultaneous determination of both carbaryl and fenamiphos with excellent sensitivity. The characteristics of the modified electrode were studied with transmission electron microscopy, X-ray diffraction and Fourier transform-infrared spectroscopy techniques. Under optimized conditions, the rGO/Cu/CuO-Ag/GCE detected carbaryl and fenamiphos with the wide linear ranges of 0.05–20 and 0.01–30 μM, and the detection limits were 0.005 and 0.003 μM, respectively. This developed electrochemical platform applied as a simple and cost-effective sensor for the detection of low levels of carbaryl and fenamiphos in fruit and vegetable samples successfully.

A sensitive prostate-specific antigen (PSA) detection method using a visual-readout closed bipolar electrode (BPE) system has been introduced by integration of hydrogen evolution reaction (HER) in cathodic pole and electrochemiluminescence (ECL) of luminol loaded within the MIL-53(Fe)-NH

In this work, we demonstrated the development of a colorimetric immunosensor using surface plasmon resonance band of gold nanoparticles for the detection of prostate specific antigen (PSA). To develop this biosensing tool, triangular gold nanoparticles (AuNPs) were synthesized using Tween-20 as a nonionic surfactant and then, conjugated with PSA capture antibody (Ab1-AuNPs). When exposed to Ab1-AuNPs, PSA antigens were found to be successfully captured by nanosystem (PSA)-Ab1-AuNPs. Next, (PSA)-Ab1-AuNPs were incubated with second PSA antibody (2)-decorated magnetite (Fe3O4-Ab2) and separated by an external magnetic force to leave Ab1-AuNPs in the supernatant solution to be directly analyzed using UV–Vis spectroscopy. It was found that the absorption intensity was directly proportional to the PSA concentration. As a result, the linear range for PSA detection was found to be 0.01–20 ng mL−1 with a detection limit of 0.009 ng mL−1. Because of significant stability of the prepared Ab1-AuNPs and excellent selectivity to the PSA antigen, this simple and sensitive sensing system is proposed to be potentially effective in the fast and real-time analysis of clinical samples from prostate cancer patients. We believe that the simple platform of this immunosensor to be useful in the development of future point-of-care sensing tools, working on the quantification of biomarkers in a drop of blood.

Herein, by taking advantage of the special binding of an aptamer to the membrane surface of a B cell and accumulation of the positive charges of a nanocomposite, including luminol-chitosan-platinum nanoparticles (L-Cs-Pt NPs), on the negatively charge of the aptamer phosphate backbone, a sensitive, simple, selective and rapid strategy for the detection of lymphoma cells by a new label-free electrogenerated chemiluminescence (ECL) aptasensor has been introduced. With increasing concentrations of B lymphoma cells, the nanocomposite detaches from the aptamer, leading to a decrease in the ECL of a luminol and H2O2 system. With high loading of luminol and Pt NPs on a chitosan, together with the electrocatalytic effect of Pt NPs, enhanced sensitive detection of cancer cells with a limit of detection of 31 cells/mL was achieved. Step-by-step modification and biosensor response to cancer cells was monitored by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and ECL. The aptasensor exhibited excellent specificity for lymphoma cells vs breast cancer (MCF-7) and human embryonic kidney (HEK293) cell lines as potential interferents. Finally, the performance of the aptasensor in blood samples was assessed against a commercial flow cytometric method. Satisfactory results confirmed the applicability of the proposed biosensing platform.

This work describes the development of a new sensor for simultaneous determination of tryptophan and melatonin. The proposed sensor was an ionic liquid carbon paste electrode modified with reduced graphene oxides decorated with SnO2-Co3O4 nanoparticles. The voltammetric oxidation of the analytes by the proposed sensor confirmed that the electrooxidation process undergoes a two-electron/one-proton reaction for melatonin and a two-electron/two-proton reaction for tryptophan in diffusion-controlled processes. Moreover, based on the excellent electrochemical properties of the modified electrode, a sensitive voltammetric method was used for individual and simultaneous determination of melatonin and tryptophan in the aqueous solutions. Under the optimized experimental conditions, a linear response obtained in the range of 0.02 to 6.00μmolL-1 with detection limits of 4.1 and 3.2nmolL-1 for melatonin and tryptophan, respectively. The prepared sensor possessed accurate and rapid response toward melatonin and tryptophan with a good sensitivity, selectivity, stability, and repeatability. Finally, the applicability of the proposed sensor was verified by evaluation of melatonin and tryptophan in various real samples including human serum and tablet samples.

In this study, a sensitive carbon paste electrode based on a novel nanocomposite of carbon dots/CuFe2O4 (C-dots@CuFe2O4) was developed for the simultaneous determination of rifampicin (RIF) and isoniazid (INZ). The morphological and structural properties of the C-dots@CuFe2O4 were well characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Under the optimized conditions, the voltammetric current increased linearly on increasing the concentration of RIF and INZ in the range of 0.07 to 8.0 and 0.1 to 14.0 μmol L−1, respectively. Moreover, the detection limits for the analytes were calculated to be 0.022 μmol L−1 for RIF and 0.041 μmol L−1 for INZ based on 3Sb/m. The practical applicability of the proposed sensor was examined by evaluating the detection of RIF and INZ in biological fluids and pharmaceutical samples with satisfactory recoveries. The C-dots@CuFe2O4/CPE can hold great promise for fast, simple and sensitive detection of RIF and INZ in various real samples.

In this work, a novel electrochemical sensing platform was successfully prepared by electrodeposition of gold nanoparticles on the electropolymerized layer of poly-melamine modified pre-anodized glassy carbon electrode. The surface morphology and electrochemical behaviour of the modified electrode (PMel-Aunano/GCE*) were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The proposed sensor remarkably increased the oxidation responses of rifampicin (RIF) associated with a significant decrease in its peak over-potentials of about 0.10 V based on the integration of the beneficial effects of a conductive PMel (with excellent electrocatalytic activity) and gold nanoparticles (with prominent electrochemical properties and large surface area), which exhibits the properties of their individual components with synergistic effects. The results demonstrated that voltammetric determination of RIF achieved favourably and the modified electrode represents two oxidation peaks for rifampicin at potentials approximately 0.09 V (peak 1) and 0.70 V (peak 2) in phosphate buffer solution with a linear range of 0.08–15.00 μM and a detection limit of 0.03 μM. The developed sensor is stable, reproducible and feasible for long-term use in biological samples with satisfactory results for RIF detection.

A novel biosensing platform based on fractal-pattern of iron oxides magnetic nanostructures (FIOMNs) and mixed hemi/ad-micelle of sodium dodecyl sulfate (SDS) was designed for the magnetic immobilization of hemoglobin (Hb) at a screen printed carbon electrode (SPCE). The FIOMNs was successfully synthesized through hydrothermal approach and characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). In order to provide guidelines for the mixed hemi/ad-micelle formation, zeta-potential isotherms were investigated. The construction steps of the biosensor were evaluated by electrochemical impedance spectroscopy, cyclic voltammetry and Fourier transform infrared spectroscopy. Direct electron transfer of Hb incorporated into the biocomposite film was realized with a pair of quasi-reversible redox peak at the formal potential of -0.355V vs. Ag/AgCl attributing to heme Fe(III)/Fe(II) redox couple. The results suggested that synergistic functions regarding to the hyper-branched and multidirectional structure of FIOMNs and the dual interaction ability of mixed hemi/ad-micelle array of SDS molecules not only induce an effective electron transfer between the Hb and the underlying electrode (high heterogeneous electron transfer rate constant of 2.08s(-1)) but also provide powerful and special microenvironment for the adsorption of the redox proteins. Furthermore, the biosensor displayed an excellent performance to the electrocatalytic reduction of H2O2 with a detection limit of 0.48µM and Michaelis-Menten constant (Km) value of 44.2µM. The fabricated biosensor represented the features of sensitivity, disposable design, low sample volume, rapid and simple preparation step, and acceptable anti-interferences, which offer great perspectives for the screen-determination of H2O2 in real samples.

An Au-Pd/reduced graphene oxide composite was employed as a novel electrode material for the sensitive and simultaneous determination of ascorbic acid, acetaminophen and tyrosine. The electrochemical response characteristics of the modified electrode toward the analytes were investigated by differential pulse voltammetry and cyclic voltammetry. The responses of the electrochemical sensor for the target analytes were found to be improved significantly in comparison with those obtained using a conventional carbon paste electrode (CPE) and reduced graphene oxide/CPE. The experimental conditions for simultaneous determination of these species have been established. Ternary mixtures of analytes can be determined in the ranges of 0.03-9.50μM. Under optimal conditions, the limits of detection were 15.7, 7.6 and 11.1nM for ascorbic acid, acetaminophen, and tyrosine, respectively. The method was applied successfully to determine the analytes in urine, serum and pharmaceutical samples simultaneously.

A new method for the selective extraction of p-aminosalicylic acid from aqueous and urine samples has been developed using magnetic molecularly imprinted polymer nanoparticles before determination by high-performance liquid chromatography. The Fe3O4 nanoparticles were first prepared through the chemical co-precipitation of Fe2+ and Fe3+ and coated then with a vinyl shell. Subsequently, a layer of molecularly imprinted polymers was grafted onto the vinyl-modified magnetic nanoparticles by precipitation polymerization. FTIR spectroscopy, scanning electron microscopy, vibrating sample magnetometry and thermogravimetric analysis were applied to characterize the sorbent properties. Moreover, the predominant parameters affecting the magnetic solid phase extraction such as sample pH, sorption and elution times, the amount of sorbent, and composition and volume of eluent were investigated thoroughly. The maximum sorption capacity of imprinted polymer toward para-aminosalicylic acid was found to be 70.9 mg g−1, which is 4.5 times higher than that of the magnetic non-imprinted polymer. The magnetic molecularly imprinted polymer nanoparticles were applied for the selective extraction of p-aminosalicylic acid from aqueous and urine samples and satisfactory results were achieved. The results illustrate that magnetic molecularly imprinted polymer nanoparticles have great potential in the extraction of p-aminosalicylic acid from environmental and biological matrices. This article is protected by copyright. All rights reserved

Background and Aim: Anti-inflammatory cytokine IL-10 is important and single nucleotide polymorphisms in the interleukin-10 gene promoter is associated with HBV infection. Especially single nucleotide polymorphisms in the promoter region of the gene IL10, at position -1082, -819, -592 is associated with production of IL10. Therefore, the present study was to determine the effect of IL-10 -819 polymorphism with chronic HBV infection in Iranian patients. Materials and Methods: A total of 200 subjects (100 chronically infected hepatitis B patients and 100 blood donors) with an age range of 18-59 years were included in this study randomly.The study in 1392 on samples of patients referred to clinical laboratory blood transfusion was performed. Genomic DNA was extracted from Buffy coat layer with using of salting out procedure.Allele Specific Polymerase Chain Reaction Method was used for determining polymorphisms -819 (C/T) in the IL-10 gene promoter.Electrophoresis was performed on a arose gel 1.5 per cent for the detection of PCR products. Data were analyzed using Chi Square analysis Results: The frequency of Homozygote genotype IL-10 -819 (TT, TC, CC) was in patients with HBV 84%,12% and 4% and 89%,10% and 1% in healthy individuals respectively and no significant difference was observed between the two groups in terms of genotype (P =0.8). Variant of C allele frequency was in patients with HBV 10% and 6% in healthy individuals. There was no statistically significant difference between the two groups (P=.0.6). Conclusions: Our results showed that there was no correlation between polymorphism IL-10-819(T/C) in control group and chronic Hepatitis B infection.

In this research, a new strategy for construction of a development potentiometric carbon paste Zn2+-ion selective electrode based on a novel nano-sensing layer is suggested. The proposed nano-sensing layer was prepared with the addition of a synthesised Zn2+-ion imprinted polymer nanoparticles ‘as an efficient sensing agent’ into the carbon paste matrix consisting of graphite powder, nanographene-composite ‘graphene nanosheets decorated with silver nanoparticles’ and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ‘ an ionic liquid ’, as the conducting binder. Under the optimised experimental conditions, the suggested nanographene-composite potentiometric sensor presented a low detection limit of 1.93 × 10−1 μg L−1 and a linear analytical range from 2.62 × 10−1 to 6.54 × 105 μg L−1 with an excellent Nernstian slope of 29.80 mV decade−1. The proposed zinc selective sensor was successfully applied for the highly sensitive determination of trace amounts of Zn2+ in environmental and bi...

In this study, a novel impedimetric immunosensor based on Au nanoparticles@ multiwall carbon nanotubes-graphene quantum dots (AuNPs@MWCNTs-GQDs) was designed for the detection of prostate cancer biomarker with high sensitivity and selectivity in human serum. This label-free immunosensor was constructed by glassy carbon electrode surface coating with AuNPs@MWCNTs-GQDs as a signal amplifier and then an antibody against ،Prostate specific antigen)PSA(was immobilized on the modified electrode. The constructed immunosensor was characterized using transmission electron microscopy (TEM), Energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Fourier transform infrared (FTIR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. EIS measurements were applied to investigate the specific immuno-interactions at the immunosensor surface utilizing redox probe [Fe (CN)6]3−/4− to detect prostate specific antigen (PSA). The label-free immunosensor was successfully used to improve the analytical performance significantly and the impedance increment was linearly related to the PSA concentration in a wide linear range of 1–10,000 pg/mL and a low detection limit of 0.48 pg/mL. The responses of the proposed immunosensor in the real samples were compared with the commercial enzyme-linked immunosorbent assay (ELISA) method. The obtained were in good agreement with those obtained by the reference ELISA method. Therefore, this sensor with high sensitivity, selectivity and repeatability, could be utilized for early clinical diagnosis of prostate cancer in the clinical laboratories.

In this paper, we have presented the syntheses feasible scheme for reliable and suitable construction, using a two-step hydrothermal/ grinding method, g-AgI@TiO2/UiO-66-NH2 (gAT/U6N) composites. The photocatalytic efficiency was calculated by the elimination of Rhodamine B (RhB) by visible light radiation. Consequently, the optimized (AT30-U6N) exhibited a noteworthy photocatalytic performance and a rapid degradation ability for Rhodamine B with a removal efficiency of 82.9 % in 30 min, which was considerably enhanced than those of bulk U6N (22 %), bulk TiO2 (16.8 %), pure AgI (29 %) and g-AT under the identical conditions, proffering a synergistic efficacy in the hybrid materials. Remarkable amelioration in Photocatalytic efficiency was caused by the ternary structure of TiO2, U6N and photoelectrical efficiency of AgI, strongly absorbing visible light irradiation and promoting photoelectrons Transfer. This research demonstrates the superior outcome of ternary 30AT@U6N Z-scheme photocatalyst in dyed wastewater and creates a unique vision in improving U6N.

In this paper, we introduce an easy method for the synthesis of bimetallic gold and palladium nanoparticles coated on reduced graphene oxide (Au-Pd/rGO nanocomposite). Also, the application of this nanocomposite for modification of carbon paste electrode (CPE) for electrochemical determination of Parathion (PAR) in aqueous solution is investigated. The synthesised Au-Pd/rGO was characterised using scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS). The cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV) were employed to evaluate the electrochemical performance of the modified electrode toward PAR. The parameters which can affect the response of Au-Pd/rGO/CPE for determination of the analyte, such as pH, accumulation potential and time were optimised. The electrode represents a linear response at 0.01 to 11.2 µM and a detection limit of 0.008 µM under the optimised condition. The impact of some potential interfering species on the electrochemical determination of PAR were examined, and Au-Pd/rGO/CPE illustrates a good selectivity for determination of PAR. Finally, the modified electrode was applied to determine PAR in different spiked real samples with various matrixes including cucumber, cabbage, groundwater and tap water. The obtained results and the percentage of recoveries show an excellent capability of the proposed sensor for the detection of PAR in real samples.

In this study, for the first time, a novel MOF based nanocomposite, UiO-66@ WO3/graphene oxide (UiO-66@WG) was synthesized by a solvothermal method and its ability was evaluated for photodegradation of two pollutant models containing aromatic (tetracycline (TC)) and nonaromatic (malathion (MA)). The characterization of nanocomposite was performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and N2 adsorption–desorption technique. The best efficiencies (84% and 100% for TC and MA respectively) obtained using UiO-66@35WG under 70 min visible light irradiation which is noticeably more efficient when compared with pure UiO-66. This enhancement arises from several aspects containing increase in visible light response, proper matching of conductive and valence bands belong to UiO-66 and WO3 that led to improved separation of electron-hole pair and faster transfer of photoinduced carriers on layers of graphene oxide. The reduced band gap, various functional groups and good availability of active sites also are other positive factors in this design. The total oxygen carbon (TOC) analysis indicated 75%, 83% mineralization efficiency for TC and MA respectively, indicating acceptable decomposition of these pollutants under optimum condition. Furthermore, this nanocomposite shown good reusability after 4 consecutive runs.

A nanostructured material of the type Au-ZnO-SiO2 is described that consists of ZnO and gold nanoparticles (NPs) dispersed into a silica matrix and used to construct a voltammetric sensor for 4-nitrophenol. The AuNPs and ZnO NPs are anchored onto the silica network which warrants the nanostructures to be stable in various environments. It also facilitates the electron transfer between the electrolyte and the glassy carbon electrode (GCE). The properties of the nanostructure as a modifier for the GCE were investigated by energy dispersive spectrometry, X-ray diffraction spectroscopy, and transmission electron microscopy. It is shown that the nanostructure increases the surface area. Hence, the cathodic and anodic current in differential pulse voltammetry of 4-nitrophenol are considerably enhanced in comparison to a bare GCE. Under optimum conditions, the currents for oxidation and reduction are proportional to the concentration of 4-nitrophenol in the 0.05–3.5 μM and 0.01–1.2 μM concentration ranges, with 13.7 and 2.8 nM detection limits, respectively. The sensor has excellent sensitivity, fast response, long-term stability, and good reproducibility. It is perceived to be a valuable tool for monitoring 4-nitrophenol in real water samples.

In the present study, graphene oxide reinforced two-phase electromembrane extraction (EME) coupled with gas chromatography was applied for the determination of methamphetamine as a model analyte in biological samples. The presence of graphene oxide in the hollow fiber wall can increase the effective surface area, interactions with analyte and polarity of support liquid membrane that leads to an enhancement in the analyte migration. To investigate the influence of the presence of graphene oxide in the support liquid membrane on the extraction efficiency, a comparative study was performed between graphene oxide and graphene oxide/EME methods. The extraction parameters such as type of organic solvent, pH of the donor phase, stirring speed, time, voltage, salt addition and the concentration of graphene oxide were optimized. Under the optimum conditions, the proposed microextraction technique provided low limit of detection (2.4 ng/mL), high preconcentration factor (195-198) and high relative recovery (95-98.5%). Finally, the method was successfully employed for the determination of methamphetamine in urine and hair samples.

In the present study, a novel nano-layer sensing materials for the fabrication of a newly modified potentiometric carbon paste electrode was introduced. Its sensing layer was prepared with the incorporation of 1-(3-imino-4-hydroxophenylazo-4 nitrobenzene) isonicotinohydrazide “as an efficient ionophore” into the matrix consisting of graphite powder, synthesized graphene nanosheets, synthesized CdO nanowires, and diphenylacetylene (a typical molecular wire as the conductive binder). The suggested nanocomposite carbon paste electrode gave a Nernstian behavior in the linear range of 3.50 × 10−9 to 1.00 × 10−2 M with the detection limit of 1.44 × 10−9 M. For investigation of the electrochemical behavior of Cu2+ at the surface of the unmodified and modified electrodes, the differential pulse voltametric method was used. The proposed sensor was successfully applied in the determination of copper ions in some foodstuff real samples with satisfactory results.