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In this study, a super-active Iron (II, III) oxide nanospheres (Fe 3 O 4 NPs) decorated reduced graphene oxide (rGOS) nanocomposite was developed. Fe 3 O 4 NPs were stabilized on rGOS through electrostatic interactions in the aqueous medium. This process involves an ultrasound assisted reduction reaction of the GOS. The as-synthesized Fe 3 O 4 NPs@rGOS was characterized through the HRTEM, SEM, XRD, Raman, elemental mapping and EDX analysis. The Fe 3 O 4 NPs@rGOS modified GCE was developed for the determination of biomarker. Uric acid is important biomarker based on gout and kidney stone with high adverse effect in human body. The results obtained showed that the modified electrode Fe 3 O 4 NPs@rGOS shows good electrochemical reduction peak compared to bare electrode and control electrodes. The Fe 3 O 4 NPs@rGOS modified sensor linear range 0.02-783.6 µM was observed with nanomolar LOD 0.12 nM. In addition, the modified Fe 3 O 4 NPs@rGOS/GCE sensor has been applied to determination of uric acid concentration in urine and blood serum samples. Furthermore, advantages of the modified sensor are high stability, repeatability and reproducibility., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Herein, we report a super-active electrocatalyst of copper(II) oxide nanoparticles (CuO NPs) decorated functionalized multiwalled carbon nanotubes (CuO NPs@f-MWCNTs) by the ultrasonic method. The as-synthesized CuO NPs@f-MWCNTs was characterized through the FESEM, XPS, XRD and electrochemical impedance spectroscopy (EIS). The combination of highly active CuO NPs and highly conductive f-MWCNTs film with rapid detection enables this nanohybrid to display excellent electrochemical performance towards anesthesia drug. Furthermore, the hybrid electrocatalyst modified SPCE was developed for the determination of flunitrazepam (FTM) for the first time. FTM is important anesthesia drug with high adverse effect in human body. Benefiting from the synergistic reaction of CuO NPs and f-MWCNTs, this nanohybrid exhibited high sensitivity and specificity towards FTM electro-reduction. The CuO NPs@f-MWCNTs film modified SPCE exhibits outstanding electrochemical activity including excellent reproducibility, wide linear range from 0.05 to 346.6 µM with nanomolar limit of detection for FTM detection. Further, the as-modified CuO NPs@f-MWCNTs/SPCE has been applied to determination of FTM in biological and drug samples with satisfactory recovery results, thereby showing a notable potential for extensive (bio) sensor applications., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A simple and facile ultrasound based sonochemical method to incorporate Perovskite-type barium titanate (BaTiO 3 ) nanoparticles inside the layered and reduced graphene oxide sheets (rGOs) is reported. BaTiO 3 @rGOs nanocomposite was characterized by FESEM, HRTEM, EDX, mapping, XRD, XPS and EIS. The results show that the decoration and also incorporation of BaTiO 3 nanoparticles in the multi-layered and ultrasound reduced graphene oxide matrix. Non-enzymatic and differential pulse voltammetric sensor of ractopamine (food toxic) based on the BaTiO 3 @rGOs nanocomposite modified screen printed carbon electrode is developed. Compared with the original BaTiO 3 /SPCE and rGOs/SPCE, the BaTiO 3 @rGOs/SPCE displays excellent current response towards ractopamine and gives linearity in the range of 0.01-527.19 µM ractopamine in neutral phosphate buffer (pH 7.0). The BaTiO 3 @rGOs nanocomposite modified sensor also exhibits valuable ability of anti-interference to electroactive analytes. Furthermore, the as-prepared BaTiO 3 NPs@rGOs/SPCE has been applied to the determination of ractopamine in pork and chicken samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The nanomaterials have received enormous attention in the catalysis applications. Particularly, we have focused on the fabrication of nanocomposite for an electrochemical sensor with improved electrocatalytic performance. Herein, a rapid and sensitive electrochemical detection of nitrite is essential for assessing the risks facing ecosystems in environment. We report a simple and robust ultrasonic-assisted synthetical route via prepared Er 2 O 3 nanoparticles decorated reduced graphene oxide nanocomposite (Er 2 O 3 NPs@RGO) modified electrode for nitrite detection. The composition and morphological formation were characterized by XRD, XPS, FESEM, and HRTEM. The amperometric (i-t) and cyclic voltammetry were exhibits tremendous electrocatalytic capability and superior performance toward nitrite oxidation. A sensitive and reproducible amperometric nitrite sensor was fabricated which able to detect trace concentration as 3.69 nM and excellent sensitivity (24.17 µA µM -1  cm -2 ). The method worked well even in cured meat and water samples and the results has indicates the reliability of the method in real-time analysis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Herein, we have reported a simple sonochemical synthesis of multi-layer graphene covered tungsten trioxide nanoballs (WO 3 NBs) and the nanocomposite was characterized by FESEM, HRTEM, XRD, XPS, CV and EIS. Furthermore, progesterone (PGT) is a preferred marker for various biological problems like pregnancy problem, mood swings, anxiety, depression, nervousness and body pain. Therefore, its selective and sensitive determination in various biological fluids is beneficial for the evaluation of malformation problems. We describe the fabrication of an amperometric and non-enzymatic biosensor based on WO 3 NBs@GR nanocomposite modified electrode for nanomolar detection of PGT. The results showed that the nanocomposite modified electrode exhibit well-defined electro-oxidation peak compared to bare and control electrodes, demonstrating the superior electrocatalytic ability and performances. The fabricated modified sensor was facilitates the analysis of PGT in the concentration ranges of 0.025-1792.5 µM with a low detection limit of 4.28 nM. Further, the as-prepared WO 3 NBs@GR electrode has been applied to determination of PGT in human blood samples with outstanding recovery results and more importantly, the facile and environment-friendly sonochemical construction strategy extended here, may be open a cost-effective way for setting up the nanocomposites based (bio) sensing platform., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this paper, mesoporous tungsten sulfide electrocatalyst (MP-WS 2 ) were developed through a facile sonochemical technique (SC) and utilized as an electrocatalyst for the sensitive electrochemical detection of Psychoactive drug. The as-prepared SC-MP-WS 2 NRs and HT-WS 2 NPs (hydrothermally synthesized) were characterized using XRD, Raman, XPS, FESEM, HRTEM, BET, EDX, and electrochemical analysis, which exposed the formation of WS 2 in the form of mesoporous nanorods in shape. Further, the use of the as-developed SC-MP-WS 2 NRs and HT-WS 2 NPs as an electrocatalyst for the detection of clonazepam (CNP). Interestingly, the SC-MP-WS 2 NRs modified screen-printed carbon electrode (SC-MP-WS 2 NRs/SPCE) exhibited an excellent electrocatalytic performance, and enhanced reduction peak current when compared to HT-WS 2 NPs with unmodified electrode. Moreover, as-prepared SC-MP-WS 2 NRs/SPCE displayed wide linear response range (10-551 µM), lower detection limit (2.37 nM) and high sensitivity (24.32 µAµM -1 cm -2 ). Furthermore, SC-MP-WS 2 NRs/SPCE showed an excellent selectivity even in the existence of potentially co-interfering compounds. The proposed sensor was successfully applied for the determination of CNP in biological and drug samples with acceptable recovery., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Herein, we developed a silver nanoparticles decorated iron pyrite flowers (FeS 2 @Ag NL) based nanocomposite was prepared by a sonochemical method. The formation of FeS 2 @Ag NL nanocomposite was confirmed by XRD, XPS, HR-TEM and analytical techniques. The FeS 2 @Ag NL/SPCE was potentially applied towards electrochemical detection of toxic herbicide (acifluorfen-AFF). This provided an efficient sensor platform anchoring FeS 2 @Ag NL on its surface. Under optimized conditions of differential pulse voltammetric transduction, a linear relationship between the current and the concentration was obtained in the range of 0.05-1126.45 µM for Acifluorfen. The detection limit was observed to be 0.0025 µM. the modified sensor exhibits excellent electrochemical performance, including good linear range, nanomolar detection limit, high sensitivity, and desirable stability. Particularly, the practical applicability was revealed by quantifying the AFF concentration in biological samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)