Fe3O4 nanoparticles decorated reduced graphene oxide&carbon nanotubes-based composite for sensitive detection of imatinib in plasma and urine

In this study, a new reduced graphene oxide (rGO) has been synthesized via a facile and envi­ronmentally friendly process using Callicarpa maingayi leaf extract. A novel magnetic catalyst based on Fe3O4 nanoparticles-reduced graphene oxide&carbon nanotubes ((Fe3O4- -(rGO&CNT)) was prepared and characterized by hydrothermal method. The Fe3O4 nanoparticles with an average size of 25 to 40 nm were placed on carbon nanotubes and reduced graphene oxide sheets, while carbon nanotubes inserted between the reduced graphene oxide sheets effectively prevented their aggregation. The (Fe3O4-(rGO&CNT) composite has a large surface area and good electrocatalytic properties, suiting for the detection and determination of imatinib (IM) anticancer drug by voltammetry method. Under opti­mi­zed conditions, good linearity was achieved in the concentration range of 0.1 to 40 μmol L-1 and the limit of detection and sensitivity were 57 nmol L-1 and 3.365 μA L μmol-1, respectively. Furthermore, the fabricated sensor demonstrated acceptable reproducible behaviour and accuracy and a high level of stability during all electrochemical tests. In addition, the proposed method was applied for the detection of IM in biological samples and the recoveries were 94.0 to 98.5 %, with relative standard deviations of 2.1 to 4.4 %.

Synthesis of silver nanocatalyst in presence of poly(ethylene glycol) and its application for electrocatalytic reduction of hydrogen peroxide

The synthesis of powdered Ag nanoparticles in presence of poly(ethylene glycol) as reducing agent and stabilizer in aqueous medium is reported. The structure and properties of the Ag nanoparticles have been characterised by X-ray diffraction, transmission electron microscopy and energy dispersive X-ray data. XRD study shows that the particles are crystalline in nature with face centered cubic geometry. Formation of stable silver nanoparticles gives mostly spherical particles with diameter in the range of 12–30 nm. The catalytic activity of the nanocrystalline AgNPs, for the reduction of hydrogen peroxide has been studied at the surface of glassy carbon electrode modified with Ag nanoparticles and poly(methyl methacrylate) (AgNPs-PMMA/GCE) prepared by casting of the AgNPs-PMMA solution on GCE. The sensor responds to H2O2 with high selectivity, good reproducibility and stability, over a linear range of 22–1700 µM with a detection limit of 4.8 µM using amperometry.

Magnetite graphene oxide-albumin conjugate: carrier for the imatinib anticancer drug

Abstract Carbon nanomaterials are widely used in biomedical applications due to their versatile properties. These are the attractive candidates for the carrying of anticancer drugs, genes, and proteins for chemotherapy. Imatinib is an effective chemotherapy drug whose toxicity has created a significant limitation in treatment. In this research, a new biocompatible nanocarrier based on albumin-magnetite graphene oxide conjugates was reported for the loading and release of imatinib. The magnetite graphene oxide nanocomposite was investigated by ultra violet-visible spectroscopy (UV-Vis), field emission scanning electron microscope (FE-SEM), X-ray diffraction spectroscopy (XRD) and energy diepersive X-ray spectroscopy (EDX) methods. The crystallite size of Fe3O4 nanoparticles on graphene oxide obtained from XRD is about 14 nm which is in agreement well with the SEM results. We show that magnetite graphene oxide conjugated with albumin is an extremely efficient carrier. An efficient loading of IM, 81% at pH 7.0, time 2 h and initial concentration of 1 mg/mL was seen onto magnetite graphene oxide-albumin in comparison to graphene oxide and magnetite graphene oxide due to the presence of oxygen and nitrogen functional groups of albumin. Upon the pH 9.0 and 7.0, 7% and 16% imatinib could be released from the magnetite graphene oxide-albumin in a time span of 5 h but when exposed pH 4.0 the corresponding 31% was released in 5 h. After 20 h, 21, 42 and 68% of imatinib was released at pH 9.0, 7.0 and 4.0, respectively. This illustrates the major benefits of the developed approach for biomedical applications. Graphical Abstrac

Synthesis of silver nanocatalyst in presence of poly(ethylene glycol) and its application for electrocatalytic reduction of hydrogen peroxide

843-847The synthesis of powdered Ag nanoparticles in presence of poly(ethylene glycol) as reducing agent and stabilizer in aqueous medium is reported. The structure and properties of the Ag nanoparticles have been characterised by X-ray diffraction, transmission electron microscopy and energy dispersive X-ray data. XRD study shows that the particles are crystalline in nature with face centered cubic geometry. Formation of stable silver nanoparticles gives mostly spherical particles with diameter in the range of 12–30 nm. The catalytic activity of the nanocrystalline AgNPs, for the reduction of hydrogen peroxide has been studied at the surface of glassy carbon electrode modified with Ag nanoparticles and poly(methyl methacrylate) (AgNPs-PMMA/GCE) prepared by casting of the AgNPs-PMMA solution on GCE. The sensor responds to H2O2 with high selectivity, good reproducibility and stability, over a linear range of 22–1700 µM with a detection limit of 4.8 µM using amperometry

Direct electrochemistry and bioelectrocatalysis of a class II non-symbiotic plant haemoglobin immobilised on screen-printed carbon electrodes.

In this study, direct electron transfer (ET) has been achieved between an immobilised non-symbiotic plant haemoglobin class II from Beta vulgaris (nsBvHb2) and three different screen-printed carbon electrodes based on graphite (SPCE), multi-walled carbon nanotubes (MWCNT-SPCE), and single-walled carbon nanotubes (SWCNT-SPCE) without the aid of any electron mediator. The nsBvHb2 modified electrodes were studied with cyclic voltammetry (CV) and also when placed in a wall-jet flow through cell for their electrocatalytic properties for reduction of H(2)O(2). The immobilised nsBvHb2 displayed a couple of stable and well-defined redox peaks with a formal potential (E degrees ') of -33.5 mV (vs. Ag|AgCl|3 M KCl) at pH 7.4. The ET rate constant of nsBvHb2, k (s), was also determined at the surface of the three types of electrodes in phosphate buffer solution pH 7.4, and was found to be 0.50 s(-1) on SPCE, 2.78 s(-1) on MWCNT-SPCE and 4.06 s(-1) on SWCNT-SPCE, respectively. The average surface coverage of electrochemically active nsBvHb2 immobilised on the SPCEs, MWCNT-SPCEs and SWCNT-SPCEs obtained was 2.85 x 10(-10) mol cm(-2), 4.13 x 10(-10) mol cm(-2) and 5.20 x 10(-10) mol cm(-2). During the experiments the immobilised nsBvHb2 was stable and kept its electrochemical and catalytic activities. The nsBvHb2 modified electrodes also displayed an excellent response to the reduction of hydrogen peroxide (H(2)O(2)) with a linear detection range from 1 muM to 1000 muM on the surface of SPCEs, from 0.5 muM to 1000 muM on MWCNT-SPCEs, and from 0.1 muM to 1000 muM on SWCNT-SPCEs. The lower limit of detection was 0.8 muM, 0.4 muM and 0.1 muM at 3sigma at the SPCEs, the MWCNT-SPCEs, and the SWCNT-SPCEs, respectively, and the apparent Michaelis-Menten constant, [Formula: see text], for the H(2)O(2) sensors was estimated to be 0.32 mM , 0.29 mM and 0.27 mM, respectively

Nucleic aptamer modified porous reduced graphene oxide/MoS2 based electrodes for viral detection: Application to human papillomavirus (HPV)

International audienceNext to graphene nanomaterials, molybdenum disulfide (MoS 2) offers large surface area that can enhance its biosensing performance. In this work, we investigate the performance of glassy carbon (GC) electrodes modified successively with porous reduced graphene oxide (prGO) and molybdenum sulfide (MoS 2) for the sensitive and selective detection of the L1-major capsid protein of human papilloma virus (HPV). Owing to the difficulties to perform serological assays and HPV cultures efficiently, tools based on molecular recognition are becoming of great importance. We developed here an electrochemical sensor for HPV upon covalent functionalization of the electrode with an aptamer Sc5-c3, a RNA aptamer targeted against the HPV-16 L1 protein. Using differential pulse voltammetry (DPV) and an optimized To whom correspondence should be send to: [email protected]

Graphene-modified electrodes for sensing doxorubicin hydrochloride in human plasma

Doxorubicin (DOX), an anthracycline molecule, is currently one of the most widely used anticancer drugs in clinics. Systematic treatment of patients with DOX is known to be accompanied by several unpleasant side effects due to the toxicity of the drug. Thus, monitoring of DOX concentration in serum samples has become increasingly important to avoid side effects and ensure therapeutic efficiency. In this study, we discuss the construction of a disposable electrochemical sensor for the direct monitoring of DOX in clinical blood samples. The sensor is based on coating a gold electrode in a flexible integrated electrode construct formed on polyimide sheets using photolithography, with nitrogen-doped reduced graphene oxide (N-rGO) suspended in chitosan. Under optimized conditions, a linear relationship between the oxidative peak current and the concentration of DOX in the range of 0.010–15 μM with a detection limit of 10 nM could be achieved. The sensor was adapted to monitor DOX in serum samples of patients under anticancer treatment

Sensitive electrochemical detection of cardiac troponin I in serum and saliva by nitrogen-doped porous reduced graphene oxide electrode

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