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Herein, a simple and selective electrochemical sensor was proposed for non-enzymatic determination of hydrogen peroxide (H 2 O 2 ). This sensor was fabricated by incorporation of the novel nanostructured orthorhombic vanadium pentoxide (V 2 O 5 ) into the carbon paste electrode (CPE) which provides significant catalytic activities for H 2 O 2 reduction. The electrochemical impedance spectroscopy (EIS) studies illustrated lower charge transfer resistance (R ct ) of the V 2 O 5 modified CPE compared to the unmodified CPE. The effects of various experimental factors such as solution pH, applied potential and amount of modifier were studied in an amperometric mode. After optimization, the proposed method displayed a wide linear detection range from 5.0 to 1400.0 μM with a low detection limit of 2.5 μM based S/N = 3 and a response time less than 5 s. The sensitivity of 3.44 μA μM −1 cm −2 was acquired in the present method for H 2 O 2 quantification is considerably better than other reported amperometric sensors with similar detection limits. In addition, the designed sensor depicted good reproducibility, remarkable selectivity, and excellent stability. The modified CPE was applicable for analysis of H 2 O 2 in some cosmetic and personal care products.

In this study, a novel technique was introduced for selective surface modification of amine-functionalized magnetic nanoparticles. The method was based on alignment of magnetic nanoparticles in an external magnetic field, which resulted in formation of chain-like assemblies in diluted suspensions. The aligned chains were then modified on the surface via reaction of isocyanate species with the particle functionalities. Finally, after removal from the reactor medium, particles with segmented distribution of surface functionalities were achieved. We named these partially blocked amine-functionalized magnetic nanoparticles as "Saturn" nanoparticles. Application of the particles in fabrication of magnetic assemblies was successfully demonstrated. Using methylene diphenyl diisocyanate (MDI) as the bridging agent, structures in different forms such as chains and filaments were produced by the Saturn particles and compared with cross-linked structures of the unmodified amine-functionalized particles. It is expected that this novel nanoparticle with its unique structure will have great potential in assembly fabrication with a variety of applications in biomedical fields.

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Background: The reliable and easy-to-operate detection of hydrogen peroxide (H2O2) has attracted extensive attention in the fields of biomedicine, food security, and environmental analysis. Objectives: In this work, a novel electrochemical method was proposed for H2O2 monitoring using a carbon paste electrode (CPE) modified with MnO2/sepiolite nanocomposite. Methods: MnO2/sepiolite material was characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) technique. The modified CPE was employed for the amperometric monitoring of H2O2 in human serum samples. Results: Electrochemical data showed that the MnO2/sepiolite-CPE displays a high peak current towards H2O2 oxidation. A linear range from 5 to 700 μM and a low detection limit of 0.8 μM for H2O2 were obtained with the proposed sensor. Besides, the electrode depicted excellent reproducibility and anti-interferant ability, promising the applicability of this electrochemical method in practical analyses. Conclusions: This work introduced a new and effective enzyme-less H2O2 sensor based on the MnO2/sepiolite nanocomposite modified CPE. The suggested sensor showed good sensitivity for the rapid detection of H2O2 in a wide linear range with a low detection limit and satisfactory reproducibility, which made it practical for the analysis of hydrogen H2O2 in real samples.