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A novel electrochemical detection method based on a nickel ferrite@graphene (NiFe2O4@Gr) nanocomposite-containing molecularly imprinted polymer (MIP) was developed for the sensitive determination of butylated hydroxyanisole (BHA). After successful completion of the nanocomposite production under hydrothermal conditions, the NiFe2O4@Gr nanocomposite and a novel molecularly imprinted sensor based on the NiFe2O4@Gr nanocomposite were characterized using microscopic, spectroscopic and electrochemical techniques. According to the characterization results, the synthesis of the core–shell type NiFe2O4@Gr nanocomposite with high purity and efficiency has been proved to be successful. After successful modification of a cleaned glassy carbon electrode (GCE) with the NiFe2O4@Gr nanocomposite, analytical applications were started with the prepared BHA printed GCE. This novel molecularly imprinted electrochemical sensor for BPA detection demonstrated a linearity of 1.0 × 10−11–1.0 × 10−9 M and a low detection limit (LOD, 3.0 × 10−12 M). In addition, the BHA imprinted polymer based on the NiFe2O4@Gr nanocomposite also exhibited excellent selectivity, stability, reproducibility and reusability performances in flour analysis. [ABSTRACT FROM AUTHOR]

Herein, electrochemical tau protein immunosensor based on manganese sulfide nanoparticles/graphene oxide/polyaniline (MnS/GO/PANI) and magnetite‐incorporated gold nanoparticles (AuNPs@Fe3O4) was constructed. After the modification of the glassy carbon electrode (GCE) with MnS/GO/PANI, the immobilization and conjugation of anti‐Tau capture antibody and antigen Tau protein were successfully completed on MnS/GO/PANI/GCE, respectively. Then, the conjugation of anti‐Tau secondary antibody was carried out to AuNPs@Fe3O4 as signal amplification via amino‐gold affinity and the eventual immunosensor was accomplished by the distinctive interactions of electrode platform and signal amplification. Final immunosensor demonstrated the quantification limit (LOQ) of 1.0×10−13 M and the detection limit (LOD) of 1.0×10−14 M. [ABSTRACT FROM AUTHOR]

A novel molecularly imprinted electrochemical biosensor for glucose detection is reported based on a hierarchical N-rich carbon conductive-coated TNO structure (TNO@NC). Firstly, TNO@NC was fabricated by a novel polypyrrole-chemical vapor deposition (PPy-CVD) method with minimal waste generation. Afterward, the electrode modification with TNO@NC was performed by dropping TNO@NC particles on glassy carbon electrode surfaces by infrared heat lamp. Finally, the glucose-imprinted electrochemical biosensor was developed in presence of 75.0 mM pyrrole and 25.0 mM glucose in a potential range from + 0.20 to + 1.20 V versus Ag/AgCl via cyclic voltammetry (CV). The physicochemical and electrochemical characterizations of the fabricated molecularly imprinted biosensor was conducted by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) method, X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and CV techniques. The findings demonstrated that selective, sensitive, and stable electrochemical signals were proportional to different glucose concentrations, and the sensitivity of molecularly imprinted electrochemical biosensor for glucose detection was estimated to be 18.93 μA μM−1 cm−2 (R2 = 0.99) at + 0.30 V with the limit of detection (LOD) of 1.0 × 10−6 M. Hence, it can be speculated that the fabricated glucose-imprinted biosensor may be used in a multitude of areas, including public health and food quality. [ABSTRACT FROM AUTHOR]

TNF-α, as a pro-inflammatory cytokine, regulates some physiological and pathological courses. TNF-α level increases in some important diseases such as cancer, arthritis, and diabetes. In addition, it displays an important function in Alzheimer's and cardiovascular diseases. Herein, a novel, sensitive, and selective voltammetric TNF-α immunosensor was prepared by using gold nanoparticles involved in thiol-functionalized multi-walled carbon nanotubes (AuNPs/S-MWCNTs) as sensor platform and bimetallic Ni/Cu-MOFs as sensor amplification. Firstly, the sensor platform was developed on glassy carbon electrode (GCE) surface by using mixture of thiol-functionalized MWCNTs (S-MWCNTs) and AuNPs. Then, capture TNF-α antibodies were conjugated to sensor platform by amino-gold affinity. After capture TNF-α antibodies' immobilization, a new-type voltammetric TNF-α immunosensor was developed by immune reaction between AuNPs/S-MWCNTs immobilized with primer TNF-α antibodies and bimetallic Ni/Cu-MOFs conjugated with seconder TNF-α antibodies. The prepared TNF-α immunosensor was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). A linearity range of 0.01–1.0 pg mL−1 and a low detection limit of 2.00 fg mL−1 were also obtained for analytical applications. [ABSTRACT FROM AUTHOR]

Direct‐methanol fuel cells are proton‐exchange fuel cell in which methanol is used as the fuel. The important advantage of these fuel cells is the simplicity of transport and storage of methanol. In this study, methanol fuel cell electrocatalysts including graphene quantum dots (GQDs), functionalized multi‐walled carbon nanotubes (f‐MWCNTs) and GQDs/f‐MWCNTs composite were synthesized. The structures of synthesized electrocatalysts were highlighted by scanning electron microscope (SEM), raman spectroscopy, UV–vis spectroscopy, fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) and x‐ray diffraction (XRD) method. After that, the effective surface areas (ESA) of GQDs, f‐MWCNTs and GQDs/f‐MWCNTs were calculated. Finally, GQDs/f‐MWCNTs composite modified glassy carbon electrode (GQDs/f‐MWCNTs/GCE) showed highest current signals for methanol oxidation than those of comparable GQDs/GCE and f‐MWCNTs/GCE. [ABSTRACT FROM AUTHOR]

Abstract β-Agonists are illegally consumed in various products such as food and animal and effect the nutrition distribution owing to change of body fat. In addition, they result in acute poisoning and several symptoms such as muscular tremors and nervousness. A new electrochemical approach based on two-dimensional hexagonal boron nitride (2D-hBN) nanosheets decorated functionalized multi-walled carbon nanotubes (f-MWCNTs) was presented for simultaneous determination of β-agonists such as phenylethanolamine A (PEA), clenbuterol (CLE), ractopamine (RAC) and salbutamol (SAL) in urine samples. X-ray diffraction (XRD) method, Raman spectroscopy, scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used characterizations of nanomaterials. After that, 2D-hBN/f-MWCNTs nanocomposite modified glassy carbon electrode (GCE) was prepared for simultaneous determination of β-agonists. 1.0 × 10−12–1.0 × 10−8 M and 1.0 × 10−13 M were founded as the linearity range and the detection limit (LOD) for PEA, CLE, RAC and SAL. Finally, the prepared electrochemical sensor was used for urine sample analysis in presence of ascorbic acid (AA) and uric acid (UA). Highlights • Hexagonal Boron Nitride Nanosheets/Multi-walled Carbon Nanotubes composite is developed. • The prepared based on nanocomposite were characterized by XRD, SEM, CV and EIS. • The proposed sensor is preferred to the other methods for analysis. [ABSTRACT FROM AUTHOR]

In this report, ruthenium nanoparticles (RuNPs) and calix[4]amidocrown-5 (C4A5) were synthesized and grafted onto the surface of reduced graphene oxide (RGO) nanocomposite (RuNPs/C4A5/RGO). The morphologies of the nanocomposites were characterized by transmission electron microscope, scanning electron microscope, atomic force microscope, electrochemical impedance spectroscopy and x-ray photoelectron spectroscopy. The electrochemical experiments were performed by cyclic voltammetry, electrochemical impedance spectroscopy and square wave voltammetry. The simultaneous determination of quercetin, rutin and morin was performed on glassy carbon electrode modified with RuNPs/C4A5/RGO (RuNPs/C4A5/RGO/GCE). The linearity ranges and the detection limits of QR, RT and MR were 1.0×10−10-1.0×10−8 M and 2.0×10−11 M respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] We prepared glassy carbon electrode modified with AuNPs–modified graphene oxide. [•] The prepared composites were characterized by using various techniques. [•] The validated method was applied for determination of quercetin in pharmaceuticals. [Copyright &y& Elsevier]

Abstract: This study reports the electrochemical modification of glassy carbon (GC) surface with etodolac (ETO), the characterization of this ETO modified glassy carbon (ETO/GC) electrode and its electroanalytical application for the determination of Pb(II) ions. Binding type of the etodolac with the glassy carbon surface was investigated and found that it was through the etheric linkage revealed from the reflection–absorption infrared spectroscopy (RAIRS). The ETO/GC electrode was characterized by cyclic voltammetry (CV), reflection–adsorption IR spectroscopy, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The ETO/GC electrode was found to be suitable for selective determination of Pb(II) by adsorptive stripping voltammetry in the solutions of the mixture of heavy metal ions, such as Cu(II) and Cd(II) and showed high stability and reproducibility. The stability and the potential range of the ETO/GC electrode were also studied. The developed method was validated according to the ICH guideline and found to be linear, sensitive, selective, precise and accurate. The linearity range of Pb(II) was 5.0×10−10 to 1.0×10−8 M with the detection limit (S/N=3) of 1.67×10−10 M. The validated method was applied successfully for the determination of Pb(II) in real samples. [Copyright &y& Elsevier]

Highlights: [•] We electrochemically prepared sensor based on graphene oxide. [•] The prepared electrode was characterized by using various techniques. [•] The proposed nanosensor showed good stability, selectivity and high sensitivity. [•] The proposed nanosensor electrode was used for the analysis of Cd(II) and Cu(II). [ABSTRACT FROM AUTHOR]

Highlights: [•] Sulfisoxazole was grafted onto glassy carbon electrode. [•] The electrode was characterized by spectroscopic and electrochemical methods. [•] It has been used for the determination of Cd(II) ions in real samples in very low concentrations. [Copyright &y& Elsevier]

In this study, an ultra-sensitive electrochemical immunosensor for PSA detection was designed. Firstly, gold nanoparticles (AuNPs)/p-aminothiophenol (ATP) functionalized graphene oxide (GO) composite (AuNPs-ATPGO) was constructed and modified to glassy carbon electrode (AuNPs-ATPGO/GCE). AuNPs-ATPGO/GCE was utilized as immunosensor platform to increase the amount of PSA antibody1 (Ab 1). After that, self-assembled delaminated MXene-gold nanoparticles (d-Ti 3 C 2 T X MXene@AuNPs) was used to label PSA seconder antibody2 (Ab 2) as signal amplification. The prepared AuNPs-ATPGO, d-Ti 3 C 2 T X MXene@AuNPs and electrochemical immunosensor was charecterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), scanning electron microscope (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR). The linearity range and detection limit (LOD) were obtained as 0.01–1.0 pg mL-1 and 3.0 fg mL-1, respectively. Image 1 • Ultra-sensitive sandwich type electrochemical immunosensor is developed for prostate recognition. • The prepared immunosensor is characterized by several methods. • The prepared immunosensor shows high stability, repeatability, reproducibility and reusability. • The prepared immunosensor is preferred in comparison with the other analytical methods. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The detection of water soluble vitamins using electrochemical method is widely established in pharmaceutical quality control laboratories, and especially the recent advances in hybrid heterostrucure nanomaterials has devoted to enhance the significant analytical parameters like sensitivity, selectivity and fast response time. Herein, we report the synthesis of a hybrid heterostructure comprising SnO 2 nanoparticles supported mesoporous TiO 2 , and the obtained nanocomposite were fabricated over glassy carbon electrode (GCE) for the electrochemical oxidation of vitamin B 6 in pharmaceutical tablets. The designed SnO 2 -TiO 2 /GC modified electrode exhibits well-defined oxidation peak with lowering over-potential and larger signal response compared to the pristine counterparts, and it is mainly due to the formation of abundant active surface layer offered by SnO 2 cocatalyst, and thus significantly enhances the electrochemical surface area. Differential pulse voltammetry (DPV) measurements revealed a sharp increase in the anodic peak current upon addition of increasing concentration of vitamin B 6. The analytical performance of the modified electrode displayed a wide linear range (0.1–31.4 µM), high selectivity, and excellent sensitivity (759.73 µA mM−1 cm−2) with low detection limit (35 nM). Thus, the resultant mesoporous hybrid nanocatalyst provides an efficient electrochemical platform for determination of various potential analytes. [ABSTRACT FROM AUTHOR]

Ceftizoxime (CFX) is used to reduce the infection caused by both gram-negative and gram-positive bacteria. In this report, silver@gold nanoparticles (Ag@AuNPs) involved in 5-(5-bromo-2-hydroxybenzylidenamino)-2-mercaptobenzimidazole (ILs) was firstly synthesized. After that, CFX imprinted glassy carbon electrode (GCE) was prepared. The formation of the surfaces was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), electrochemical impedance spectroscopy (EIS) and x-ray photoelectron spectroscopy (XPS). CFX imprinted electrochemical surface was formed in the presence of 100.0 mM phenol containing 25.0 mM CFX as template. The linearity range and the detection limit (LOD) of the developed nanosensor were calculated as 1.0 × 10 − 9 - 1.0 × 10 − 11 M and 2.0 × 10 − 12 M, respectively. [ABSTRACT FROM AUTHOR]

A glassy carbon electrode (GCE) modified by calixarene functionalized reduced graphene oxide (CA/RGO) has been fabricated and utilized in this study for simultaneous voltammetric detection of several metal ions, Fe(II), Cd(II) and Pb(II), in aqueous solution. The CA/RGO nanocomposite was characterized in surface and electrochemical properties using scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Raman spectroscopy and electrochemical impedance spectroscopy (EIS). The CA/RGO coating significantly improves the sensitivity of electrochemical responses and separation of heavy metals. The electrochemical oxidation of Fe(III), Cd(II), and Pb(II) was performed by square wave voltammetry (SWV). The metal ions, Fe(III), Cd(II), and Pb(II), gave a linear relationship with their concentrations at 1.0 × 10 −10 – 1.0 × 10 −8 M on the CA/RGO/GCE. The detection limits of the metal ions were found to be similar at 2.0 × 10 −11 M. A good recovery was also obtained for practical use of the CA/RGO/GCE in pharmaceutical formulation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Glassy carbon electrode based on molecularly imprinted polypyrrole was prepared. [•] The developed surfaces were characterized by AFM, FTIR, EIS and CV. [•] The developed nanosensor was applied to egg and milk samples. [ABSTRACT FROM AUTHOR]

A highly sensitive method for detection of DNA hybridization was developed. This method was based on the modification of glassy carbon electrode with gold nanoparticles (AuNPs) involving p-aminothiophenol (ATP) functionalized graphene oxide (GO). This GO was used as a platform for impedimetric genosensing using 5′-TA GGG CCA CTT GGA CCT-(CH2)3-SH-3′ single-stranded probe (ss-DNA), 5′-AGG TCC AAG TGG CCC TA-3′ (target DNA), 5′-SH-C6-TAG GGC CA-3′ (non-complementary-1) and 5′-SH-C6-TGC CCG TTA CG 3-′ (non-complementary-2) oligonucleotide sequences. The film exhibited excellent properties for immobilizing DNA probes and sensing DNA hybridization. The DNA immobilization and hybridization on the film were studied by cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), and found that the charge transfer resistance (R ct) of the electrode increased with the concentration of the target DNA hybridized with the ss-DNA. The linear detection range was from 1.0×10−13 M to 1.0×10−7 M and the detection limit was 1.10×10−14 M (n =6). Compared with the other electrochemical DNA biosensors, the proposed biosensor showed its own performance of simplicity, good stability, and high sensitivity. [ABSTRACT FROM AUTHOR]

• Ultra-sensitive sandwich type electrochemical immunosensor is developed for procalcitonin recognition. • The prepared immunosensor is characterized by several methods. • The prepared immunosensor shows high stability, repeatability, reproducibility and reusability. • The prepared immunosensor is preferred in comparison with the other analytical methods. Septicemia, also known as sepsis, refers to a systemic inflammatory response syndrome and becomes the dominant reason of mortality for seriously diseases. Procalcitonin (PCT), the peptide precursor of the hormones, is a key biomarker of septicemia in the diagnosis and detection of bacterial inflammation. In this study, an ultra-sensitive sandwich type electrochemical immunosensor for PCT detection was constructed. Firstly, delaminated sulfur-doped MXene (d-S-Ti 3 C 2 T X MXene) modified glassy carbon electrode (GCE) including gold nanoparticles (AuNPs) was utilized as immunosensor platform to increase the amount of PCT antibody1 (Ab 1). After that, carboxylated graphitic carbon nitride (c-g-C 3 N 4) was used to label PCT Ab 2 as signal amplification. The structure of electrochemical immunosensor was highlighted by x-ray diffraction (XRD) method, scanning electron microscope (SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Herein, c-g-C 3 N 4 not only has excellent catalytic activity toward H 2 O 2 for signal amplification, but also can be directly utilized as redox probe. The analytical results have revealed that 0.01 - 1.0 pg mL-1 and 2.0 fg mL-1 were found as linearity range and limit of detection (LOD). Furthermore, the validated electrochemical immunosensor was examined in terms of stability, repeatability, reproducibility and reusability. Finally, the immunosensor was applied to plasma samples having high recovery. [ABSTRACT FROM AUTHOR]