Oxide Nanohybrid Research Articles

Silica-graphene oxide nanohybrids as reinforcing filler for natural rubber

Hybrid silica-graphene oxide (SiO2@GO) nanocomposites were fabricated by sol-gel method using tetraethylorthosilicate (TEOS) as silica (SiO2) precursor. The prepared nanocomposites were characterized by various analytical techniques to prove that the SiO2 were completely incorporated on the GO surface. Then, the SiO2@GO nanocomposites were introduced into natural rubber (NR) matrix followed by conventional vulcanization process, performed by two-roll mill, to obtain NR/SiO2@GO vulcanizate. The results showed that the presence of SiO2 nanoparticles on the GO surface improved the distribution of GO in NR matrix, resulting in the increase in modulus and hardness. For comparison with neat NR, NR/SiO2, and NR/GO, the network parameters of vulcanizates were evaluated using swelling test and tube model theory contributed in stress-strain measurement. These exhibited that the SiO2@GO induced the chemical crosslink between NR chains, leading to the increment in crosslink density. It was because the well dispersion of SiO2@GO in NR matrix improved the volume fraction of rubber. Moreover, dynamic mechanical analysis was employed to determine the viscoelasticity behavior of the vulcanizates. The results showed that the presence of SiO2@GO in NR vulcanizate improved the storage modulus in all temperature range. That meant the elasticity of the vulcanizates was improved by the reduction of the viscous phase to stiff phase ratio of the material. However, the reinforcement of NR using SiO2@GO as filler was effective in lower deformation reflected from higher modulus at low strain. In addition, the modulus decreased in comparison with that of the neat NR under higher deformation until at break point. Thus, the tensile strength decreased while elongation at break increased. This phenomenon might be explained that the strain-induced crystallization of NR occurred under higher strain was reduced because the rubber chains alignment which was obstructed by the filler penetration and high number of chemical crosslinks. Therefore, the covalent hybrid SiO2@GO nanocomposites had potential for use as filler in engineering rubber composites that were suitable for the compressive or abrasive applications.

Preparation of silica‐decorated graphene oxide nanohybrid system as a highly efficient reinforcement for woven jute fabric reinforced epoxy composites

AbstractIn the current work, silica‐decorated graphene oxide (SiO2@GONPs) nanohybrids were used to reinforce the jute fiber/epoxy (JF/EP) composite. Tetraethylorthosilicate (TEOS) was utilized to prepare the SiO2@GONPs using a facial route. The results of Fourier‐transform infrared spectroscopy (FTIR), atomic force microscopy, and elemental X‐ray mapping confirmed the successful synthesis of SiO2@GONPs nanohybrids. Herein, the effects of SiO2@GONPs loading (0, 0.1, 0.3, and 0.5 wt%) on the mechanical behavior of the JF/EP composite were investigated with emphasis on the flexural and high‐velocity impact properties. The results revealed that reinforcement of matrix with 0.3 wt% SiO2@GONPs enhanced the flexural strength of the JF/EP composite by about 40%. The energy absorption capability and impact limit velocity of the 0.3 wt% SiO2@GONPs‐filled JF/EP composite were 61 and 28%, respectively, higher than those of the neat specimen. Compared to the untreated‐GONPs, the SiO2@GONPs nanohybrid demonstrated an evident superiority in improving the mechanical properties of the JF/EP composite at the same loading. Evaluation of the fracture surfaces of the multiscale composites revealed that the improved fiber‐matrix interfacial bonding was the basic mechanism of fracture in these specimens.

Highly efficient removal of cationic, anionic and neutral dyes by hierarchically porous structured three-dimensional magnetic sulfur/nitrogen co-doped reduced graphene oxide nanohybrid

The versatile three-dimensional magnetic sulfur/nitrogen co-doped reduced graphene oxide nanomaterials (3D-MSNGs) have been constructed and generated via interfacial coordination assembly of three-dimensional sulfur/nitrogen dual-doped reduced graphene oxide (3D-SNG) with concurrent modification by formed magnetic Fe3O4. Using ferric ions as iron source, the as-obtained nanohybrid 3D-MSNG-1 possesses abundant hierarchical porous structure on graphene network, large BET surface area and favorable magnetic properties, which is proved excellent adsorption capacity and easy magnetic separation. When 3D-MSNG-1 was utilized to absorb the dyes of methylene blue (MB), congo red (CR) and neutral red (NR) considered as cationic, anionic and neutral model dye molecules, respectively, the adsorption equilibrium for MB, CR and NR were rapidly achieved in 15 min. The adsorption isotherm fits Langmuir adsorption model well with the maximum uptake capacity for MB, CR and NR high to 171.53 mg/g, 909.09 mg/g and 877.19 mg/g, respectively. Meanwhile, an efficacious treatment of ternary dyes mixed solution and a good recyclability manifests that 3D-MSNG-1 is supposed to be a superior adsorbent in the areas of water treatment.

Chitosan-capped Ag–Au/rGO nanohybrids as promising enzymatic amperometric glucose biosensor

A facile one-pot method was used to fabricate highly dispersed silver and gold nanoparticles attached to the surface of reduced graphene oxide (Ag–Au/rGO) nanohybrids via in situ incorporation of metal ions and chitosan-induced reduction. Chitosan species have a dual function in the synthesis route where they simultaneously stabilize the rGO nanosheets, furthermore Ag and Au nanoparticles nucleation as well as its reducing function. The crystal structure and morphology of the as-synthesized samples have been characterized, revealing the formation of spherical Ag and Au nanoparticles with FCC crystal structure attached to the surface of rGO nanosheets. The as-synthesized nanocomposites have shown a linear response for glucose sensing in the range from 0.25 to 25 mM with a detection limit close to 53 µM. This gluco-sensor exhibited high performance in detecting the released current in the human serum. Therefore, the results open a new route of using Ag–Au/RGO nanohybrids as a promising electrochemical biosensor.

Unravelling the synergistic effect of reduced graphene oxide on optical, phonon and optical power limiting properties of rGO/α-MoO3 nanohybrids

Reduced graphene oxide (rGO) and semiconducting metal oxide nanohybrids is an emerging class of attractive candidates towards many optical and optoelectronic applications. Herein, we investigated the nonlinear optical properties of rGO/α-MoO3 nanohybrids through open aperture z scan technique under nanosecond pulses at 532 nm excitation which shows the two-photon absorption (2PA) behavior. We found that the synergistic effect between rGO and α-MoO3 plays a significant role in the enhancement of optical power limiting properties. The variation in refractive index (n) and extinction coefficient (k) of α-MoO3 and rGO/α-MoO3 were calculated using the Kramers–Kronig (K–K) equations from the optical reflectance spectroscopic studies. The effect of rGO concentration on the lifetime phonons of singly, doubly, and triply coordinated stretching vibrations of terminal oxygen was investigated from Raman spectroscopic studies. Our experimental results imply that rGO/α-MoO3 has better optical power limiting property with the highest 2PA coefficient compared to previous literature (listed in the table).

Assessment of GO/ZnO nanocomposite for solar-assisted photocatalytic degradation of industrial dye and textile effluent.

An ecofriendly and solar light-responsive graphene oxide wrapped zinc oxide nanohybrid has been synthesized hydrothermally using lemon and honey respectively as chelating and complexing agents. By tuning the reaction conditions, a heterostructure between GO and ZnO has been formed during synthesis. The photocatalytic activity of the synthesized nanohybrid was investigated by degradation of hazardous organic textile dye (methylene blue) as well as wastewater under natural solar light. The nanohybrid exhibited excellent photocatalytic activity towards degradation (~ 89%) of methylene blue (MeB). Furthermore, along with decolorization, 71% of mineralization was also achieved. Interestingly, the nanohybrid has been found to be reusable up to 4cycles without significant loss of photocatalytic activity. Along with this, the physicochemical parameters of the wastewater generated from textile industry have been also monitored before and after exposure to nanohybrid. The results revealed significant reduction in chemical oxygen demand (COD) (96.33%), biochemical oxygen demand (BOD) (96.23%), and total dissolved solids (TDS) (20.85%), suggesting its potential applicability in textile wastewater treatment.

Synthesis and characterization of novel magnetic Zr-MnFe2O4@rGO nanohybrid for efficient removal of PFOA and PFOS from aqueous solutions

The emerging contaminants such as perfluorinated chemicals (PFCs) have been observed of increasing concerns throughout the world due to their detrimental effects for human health and other creatures in nature. Herein, zirconium imprinted magnetic manganese ferrite assembled reduced graphene oxide (rGO) nanohybrids were used to remove perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). The effective intercalation of magnetic Zr-MnFe2O4 into rGO was confirmed from FTIR, PXRD, VSM, and Raman spectra. Surface morphologies and particle sizes of as-synthesized adsorbents were determined using FE-SEM, HR-TEM, EDX, and BET analysis. Several factors including contact time, pH, initial concentrations of PFOA and PFOS, type of coexisting anions, and presence of other organic compounds were optimized to determine the maximum density of the prepared Zr-MnFe2O4@rGO nanohybrids. The adsorption of PFOA and PFOS on the Zr-MnFe2O4@rGO nanohybrids was governed mainly by electrostatic attraction followed by hydrophobic interaction. In particular, the treated adsorbents could be easily separated by employing external magnetic force, and it could be regenerated and reused up to four cycles without any significant loss. The Zr-MnFe2O4@rGO nanohybrids are potential candidates for the removal of PFOA and PFOS from aqueous environment.

Iron oxide/gold nanoparticles-decorated reduced graphene oxide nanohybrid as the thermo-radiotherapy agent.

The main focus of the current study is the fabrication of a multifunctional nanohybrid based on graphene oxide (GO)/iron oxide/gold nanoparticles (NPs) as the combinatorial cancer treatment agent. Gold and iron oxide NPs formed on the GONPs via the in situ synthesis approach. The characterisations showed that gold and iron oxide NPs formed onto the GO. Cell toxicity assessment revealed that the fabricated nanohybrid exhibited negligible toxicity against MCF-7 cells in low doses (<50 ppm). Temperature measurement showed a time and dose-dependent heat elevation under the interaction of the nanohybrid with the radio frequency (RF) wave. The highest temperature was recorded using 200 ppm concentration nanohybrid during 40 min exposure. The combinatorial treatments demonstrated that the maximum cell death (average of 53%) was induced with the combination of the nanohybrid with RF waves and radiotherapy (RT). The mechanistic study using the flow cytometry technique illustrated that early apoptosis was the main underlying cell death. Moreover, the dose enhancement factor of 1.63 and 2.63 were obtained from RT and RF, respectively. To sum up, the authors' findings indicated that the prepared nanohybrid could be considered as multifunctional and combinatorial cancer therapy agents.

Sonochemical assisted synthesis of manganese–nickel molybdate/reduced graphene oxide nanohybrid for energy storage

Abstract In the present study, manganese-nickel molybdate was synthesized using an ultrasonic assisted method for the first time. The hybrid of reduced graphene oxide (RGO) with manganese-nickel molybdate was also prepared. The structure of nanohybrid was characterized by Raman spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and inductively coupled plasma optical emission spectrometry (ICP-OES). Field emission scanning electron microscopy images showed that the manganese-nickel molybdate has the nanorod morphology. In addition, transmission electron microscopy images confirmed the presence of reduced RGO nanosheets in the nanohybrid. From ICP-OES, the nanohybrid formula was obtained as Mn0.63Ni0.37MoO4-RGO. Some electrodes with different RGO weight ratios were also prepared on nickel foam (NF) plates. Cyclic voltammetry studies showed that nanohybrid has typical faradaic redox behavior in 2 M KOH. Additionally, galvanostatic investigations showed that Mn0.67Ni0.37MoO4- RGO (60 wt %) nanohybrid can provide the high specific capacity of 161.1 mA h g−1 at 2 A g−1, which is higher than that for MnMoO4-RGO and NiMoO4-RGO nanohybrids. Furthermore, the electrode based on Mn0.67Ni0.37MoO4 provided higher specific capacity than that for MnMoO4 or NiMoO4. Owing to the synergistic effect of both Mn and Ni elements with RGO in nanohybrid, the Mn0.67Ni0.37MoO4-RGO showed the high energy density of 87 W h kg−1 at 1080 W kg−1 and the power density of 8640 W kg−1 at 9.6 W h kg−1. The electrode provided the cyclic stability about 92% of its initial capacity after 2000 cycles at 50 mV s−1. Our results showed the successful synthesis of manganese-nickel molybdate/RGO nanohybrid for the potential use in energy storage systems.

Zinc oxide nanoparticle incorporated on graphene oxide: an efficient and stable photocatalyst for water treatment through the Fenton process

Textile industries release a huge amount of wastewater that holds a very high ratio of toxic contaminants, such as dyes and various organic compounds. These are harmful to the environment, and their treatment is very much required for a clean and safe environment. So, our work explains the enhanced degradation of dye by heterogeneous Fenton process using zinc oxide-graphene oxide nanohybrid (ZnG) to generate hydroxyl radical from hydrogen peroxide. Initially, ZnG nanohybrid was successfully synthesized via hydrothermal process; later on, UV-visible spectroscopy is employed for absorption spectra and optical properties. The X-ray diffraction pattern is employed for determining the crystal structure and phase identification of nanoparticles. A scanning electron microscope (SEM) helped to find out the morphology. The high-resolution transmission electron microscopy (HRTEM) was used to get an average particle size (4.36–9.77 nm). Fluorescence spectroscopy was used to find electron-hole pair combination in nanohybrid compared to individual ZnO and GO. Finally, the catalytic activity of ZnG was successfully studied for brilliant green (BG) degradation via a heterogeneous Fenton process.

Polystyrene/thermoplastic polyurethane interpenetrating network-based nanocomposite with high-speed, thermo-responsive shape memory behavior

In the recent years, generation of flexible, mechanically tough, shape memory (SM) polymers has gained a remarkable significance both in academic section and in the field of soft robotics, smart textiles, self-deployable structures (especially used in aerospace), actuators, bio-medical devices and so on. But designing of such materials poses a credible challenge to researchers in the field. Hence, in this work, we develop a bis(hydroxyalkyl)-poly(dimethylsiloxane) capped-(3-aminopropyl)trimethoxysilane functionalized-hydroxy iron oxide anchored-reduced graphene oxide nanohybrid which serves as a reinforcing agent for the generation of nanocomposites with SM, self-tightening and hydrophobic attributes. The prepared polystyrene/thermoplastic polyurethane (PS/TPU) interpenetrating network (IPN) nanocomposites recover their original shape at a faster rate (within 20–40s upon thermal heating and within 100–140s upon exposure to sunlight) compared to other similar type SM materials (require h to min). Moreover, the nanocomposites also showed thermally actuated artificial muscle-like and self-tightening behaviors. In addition, the nanocomposite containing 1 wt% nanohybrid demonstrated >200% increase in tensile strength, >120% increase in initial thermal degradation temperature, and strong surface hydrophobicity (static contact angle >120°). Therefore, the reported nanocomposites have considerable prospect for different smart applications.

Layer-By-Layer Assembly of π-Conjugated Amine and ZnO Nanohybrids for Room Temperature CO2 Detection

I. Present study explores on the development of low molecular weight π-conjugated organic amine and metal oxide based nanohybrids for room temperature carbon dioxide (CO2) sensing application rather than using conventional polymer of organo-amines [1-4]. In this study, in-situ growth of naphthalene based π-conjugated amine (NBA) and zinc oxide (ZnO) nanohybrids thin-film were grown and their room temperature CO2 sensing performance is investigated.II. ExperimentalIn a typical experimental procedure, equimolar Zn(NO3)2∙6H2O and hexamethylenetetramine (HMTA) were added in a 20 mL of deionized water under constant stirring for 15 min at 65 °C, then NBA (10 mg) was added slowly in the solution under vigorous stirring until the solution becomes uniform reddish color. After that, the solution was transferred into a Teflon lined autoclave where the flexible substrate was placed vertically in the solution and kept at 95 °C for 3 h reaction time. III. Results and discussionFigure 1(a) shows FESEM image of hexagonal NBA-ZnO nanohybrids. EDX pattern of the NBA-ZnO nanohybrids reveals the presence of elemental C, N, Zn, and O. The sensor response to 500 ppm, 1000 ppm, 2000 ppm, 5000, and 10000 ppm CO2 were 9.1, 14.2, 21.4, 30.3, and 36.6, respectively (Figure 1(b)). The sensor response to 23%, 43%, 62%, and 85% RH was 29.9%, 29.2%, 29.4%, and 29.2%, respectively. The response changes were negligible with the increase in the relative humidity, which can be attributed to the hydrophobic nature of NBA (due to the presence of hydrophobic phenyl and naphthalene rings). During hydrothermal synthesis of NBA-ZnO nanohybrids, in the beginning, hexagonal zinc hydroxide nuclei forms from the reaction of reagents (Zn(NO3)2∙6H2O and HMTA) in the solution with the help of temperature treatment at 65 °C and constant stirring. After adding NBA in the solution, the carboxylic groups of NBA create covalent bonds with zinc hydroxide to give structural stability to the nanohybrid architecture. At the same time, the hexagonal zinc hydroxide nuclei get transformed into the nuclei of inorganic-hydroxide phases in the lamellar NBA-ZnO hybrid (Figure 1(c)). Acknowledgment Biswajit Mandal grateful to MeitY for providing fellowship under Visvesvaraya PhD scheme for Electronics and IT. Prof. Shaibal Mukherjee is thankful to MeitY for Young Faculty Research Fellowship (YFRF) under Visvesvaraya PhD scheme for Electronics and IT. This publication is an outcome of the R&D work undertaken in the project under the Visvesvaraya PhD scheme of Ministry of Electronics & Information Technology, being implemented by Digital India Corporation. Authors are thankful to FESEM and EDX facilities, which are integral parts of Sophisticated Instrument Centre (SIC) of IIT Indore.

Efficient dual-function catalysts for triiodide reduction reaction and hydrogen evolution reaction using unique 3D network aloe waste-derived carbon-supported molybdenum-based bimetallic oxide nanohybrids

The development of highly efficient catalysts has attracted great attention in energy conversion field. In this work, a series of 3D network aloe waste-derived carbon (3D-AWC)-supported molybdenum-based bimetallic oxide nanohybrids (ZnMoO4/3D-AWC, Cu3Mo2O9/3D-AWC, and MnMoO4/3D-AWC) were synthesized via co-precipitation method. Benefiting from the synergistic effect of molybdenum-based bimetallic oxide and 3D-AWC, the catalytic activities of electrocatalysts for triiodide reduction reaction (IRR) and hydrogen evolution reaction (HER) were enhanced. Solar cell with ZnMoO4/3D-AWC obtained device efficiency of 7.65%, comparable to that with Pt (6.74%), while ZnMoO4/3D-AWC catalyst delivered a Tafel slope (54 mV dec−1) in 1.0 M KOH for HER, which demonstrated a comparable property to Pt/C. In addition, the 3D-AWC-supported molybdenum-based bimetallic oxide nanohybrid catalysts exhibited superior electrochemical stability in IRR and HER. The catalytic mechanism was illustrated from electronic structure and work function by first-principle DFT calculations. This research provides a reference in designing high-performance catalysts for multi-domain energy fields.

One-step synthesis of zwitterionic\xa0graphene oxide nanohybrid: Application to polysulfone tight ultrafiltration hollow fiber membrane

In this paper, novel zwitterionic graphene oxide (GO) nanohybrid was synthesized using monomers [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) and N,N′-methylenebis(acrylamide) (MBAAm) (GO@poly(SBMA-co-MBAAm), and incorporated into polysulfone (PSF) hollow fiber membrane for the effectual rejection of dye from the wastewater. The synthesized nanohybrid was characterized using FT-IR, PXRD, TGA, EDX, TEM and zeta potential analysis. The occurrence of nanohybrid on the membrane matrix and the elemental composition were analyzed by XPS. The as-prepared tight ultrafiltration hollow fiber membrane exhibited high rejection of reactive black 5 (RB-5, 99%) and reactive orange 16 (RO-16, 74%) at a dye concentration of 10 ppm and pure water flux (PWF) of 49.6 L/m2h. Fabricated nanocomposite membranes were also studied for their efficacy in the removal of both monovalent (NaCl) and divalent salts (Na2SO4). The results revealed that the membrane possesses complete permeation to NaCl with less rejection of Na2SO4 (<5%). In addition, the nanocomposite membrane revealed outstanding antifouling performance with the flux recovery ratio (FRR) of 73% towards bovine serum albumin (BSA). Therefore, the in-house prepared novel nanocomposite membrane is a good candidate for the effective decolorization of wastewater containing dye.

Bimetallic MnCo oxide nanohybrids prepared from Prussian blue analogue for application as impedimetric aptasensor carrier to detect myoglobin

The accurate detection of myoglobin (Myo) in human serum plays a crucial role in early diagnosis of acute myocardial infarction. This work presents a novel impedimetric aptasensor for sensitive and selective detection of Myo, in which bimetallic MnCo oxide nanohybrids (represented by MnOxCoOy) were used as platforms for anchoring Myo aptamer strands. A series of MnOxCoOy nanohybrids were prepared from bimetallic MnCo-based Prussian blue analogue (PBA) nanocubes via calcination at different temperatures under N2 atmosphere. Basic characterizations revealed that homogeneously-distributed MnOx and CoOy nanoparticles were achieved at 500 °C (MnOxCoOy,500) calcination, which immensely enhanced the electrochemical conductivity in addition to boosting the aptamer immobilization. Compared with the pristine MnCo-PBA-based aptasensor, the MnOxCoOy,500-based aptasensor exhibited higher sensitivity and selectivity for Myo detection, with lower detection limit of 0.56 fg·mL−1 (0.034 fM) in a wide dynamic range of 0.01~2000 pg·mL−1, which is the most sensitive among similar previously reported Myo sensors. Moreover, the constructed MnOxCoOy,500-based aptasensor displayed good stability, excellent reproducibility and acceptable applicability in human serum. The proposed strategy establishes a remarkable platform for the construction of aptasensor that is feasible for the Myo detection in a real human serum sample.

Accelerated photocatalytic degradation of organic pollutants over carbonate-rich lanthanum-substituted zinc spinel ferrite assembled reduced graphene oxide by ultraviolet (UV)-activated persulfate

Abstract Carbonate-rich lanthanum-substituted zinc spinel ferrite assembled reduced graphene oxide nanohybrids (LaZF@rGO) were simply synthesized using a simple hydrothermal-induced precipitation process. The synthesized photocatalytic material, LaZF@rGO, showed excellent photocatalytic performance in the decolorization and mineralization of rhodamine B (RhB) under ultraviolet (UV) irradiation with the aid of peroxydisulfate. The photocatalytic activity of the optimized LaZF@rGO nanohybrids was approximately two times higher than that of zinc spinel ferrite assembled reduced graphene oxide, suggesting the critical role of lanthanum in assisting the peroxydisulfate degradation of RhB. The prepared photocatalyst was successfully utilized in the removal of a wide spectrum of selected organic contaminants such as charged dyes and pharmaceutical and personal care products under UV irradiation. The obtained “green” photocatalyst has a great potential for practical applications, since it can be regenerated and reused at least four times with negligible loss of photocatalytic activity and with insignificant leaching of potentially hazardous toxic elements (e.g., lanthanum and zinc) to the environment.

Effective adsorption of hydrogen sulfide by intercalation of TiO2 and N-doped TiO2 in graphene oxide

In this research, hydrogen sulfide was adsorbed onto the TiO2/graphene oxide (TiO2/GO) nanohybrids. In this regard, the band gap energy of the TiO2 nanoparticles was altered through nitrogen doping which influence the chemical properties of the metal oxides. The nanoadsorbents were characterized before and after adsorption of H2S. The effect of the temperature (200−220 °C) on the H2S adsorption capacity was examined. The results showed that the increase in the temperature had a positive effect on the adsorption of H2S for all of TiO2/GO hybrid nanoadsorbents. The optimum breakthrough capacities for 5%TiO2/GO, 10 %TiO/GO and 5%N-TiO2/GO was obtained at 220 °C as 0.25, 0.20 and 0.17 gS/g sorbent, respectively. The 5%N-TiO2/GO was found to be the best nanoadsorbent due to its lower band gap, higher surface area, synergic effects and presence of active sites of N-TiO2 over the nanoadsorbents. The H2S uptake capability of the 5%N-TiO2/GO nanoadsorbent was reduced to about 30–60 % after 2 regeneration cycles due to the chemisorption.

Label-free assay of protein kinase A activity and inhibition in cancer cell using electrochemically-prepared AuNP/rGO nanohybrid electrode modified with C-Kemptide

A simple, label-free and sensitive electrochemical assay is described for the detection of protein kinase A (PKA) activity and inhibition in cancer cell by measuring the change in electrochemical impedance upon phosphorylation. The assay utilized gold nanoparticle (AuNP) and reduced graphene oxide (rGO) nanohybrid which was synthesized and deposited on the electrode from GO and Au3+ precursors by one-pot electrochemical synthesis. As-prepared AuNP/rGO electrode was employed to immobilize C-Kemptide peptide substrates which was phosphorylated in the presence of PKA and ATP. The resulting assay allowed effective, selective and sensitive monitoring of PKA activity according to the impedimetric change in the range of 0.1–500 U/mL, and the detection limit (LOD) is 53 mU/mL. It could also be used for the screening of protein kinase inhibitors. Furthermore, the assay could be applied for the evaluation of PKA activity and inhibition in HeLa cell samples. Therefore, the proposed assay provides one promising tool for PKA activity detection and inhibitor screening with excellent performance.

Antibacterial activity and long-term stable antibacterial performance of nisin grafted magnetic GO nanohybrids.

In this study, magnetic graphene oxide (MGO) nanohybrids were firstly fabricated by loading Fe3O4 NPs onto GO nanosheets and then novel nisin grafted MGO (nisin-g-MGO) nanohybrids were prepared by a facile method. The nisin-g-MGO nanohybrids exhibit strong enough magnetic separation capacity. The magnetic saturation (Ms) of nisin-g-MGO nanohybrids was 23.3emu/g that enables nisin-g-MGO nanohybrids can be rapidly and completely separated from the black and stable suspension by an external magnet. The antibacterial studies of nisin-g-MGO nanohybrids show great antibacterial performance against Staphylococcus aureus and Bacillus subtilis, respectively. Moreover, the nisin-g-MGO nanohybrids exhibit long-term antibacterial stability that they still keep their good antibacterial activity after six months storage. Meanwhile, the fabricated nisin-g-MGO nanohybrids exhibit good biocompatibility without any obvious effect on HEK293 cell viability due to the calculated cell viabilities were more than 95%. And no observed changes in cell morphology were found in nisin-g-MGO nanohybrids treated HEK293 cells. Hence, the fabricated nisin-g-MGO nanohybrids exhibit great potentials in antibacterial application.

Electrochemical energy storage properties studies of Cu0.2Ni0.8O-Reduced graphene oxide nano-hybrids

Cu0.2Ni0.8O nano-particles and their nano-hybrids were synthesized by wet chemical methods and examined by X-ray diffraction (XRD) technique, spectroscopic analysis, Field Emission scanning electron microscopic (FESEM) technique and energy dispersive x-rays (EDX) analysis. XRD results confirmed that the synthesized materials were crystallite in the cubic phase of Cu0.2Ni0.8O nano-particles annealed at 500 and 800 °C. The crystallite size synthesized product was found to be around 5–20 nm. FTIR and EDX results were supporting XRD data. Morphological studies represented the spherical nature of Cu0.2Ni0.8O nano-particles annealed at 500 and 800 °C with particle size <70 nm. Electrochemical measurements of Cu0.2Ni0.8O nano-particles annealed at 500 and 800 °C and their nano-hybrids were also performed. Brilliant specific capacitance (303 F g-1) was observed in the case of rGO-based nano-hybrid of Cu0.2Ni0.8O nano-particles annealed at 500 °C. This additional noted specific capacitance was credited to more conducting nature and relatively high surface area of graphene.