We are reviewing the state of electrochemical sensing of H2O2 based on the use of metal nanoparticles. The article is divided into subsections on sensors based on nanoparticles made from Ag, Pt, Pd, Cu, bimetallic nanoparticles and other metals. Some sensors display high sensitivity, fast response, and good stability. The review is subdivided into sections on sensors based on heme proteins and on nonenzymatic sensors. We also discussed the challenges of nanoscaled sensors and their future aspects.

Electrochemical sensing of hydrogen peroxide using metal nanoparticles: a review

The green synthesis (GS) of different metallic nanoparticles (MNPs) has re-evaluated plants, animals and microorganisms for their natural potential to reduce metallic ions into neutral atoms at no expense of toxic and hazardous chemicals. Contrary to chemically synthesized MNPs, GS offers advantages of enhanced biocompatibility and thus has better scope for biomedical applications. Plant, animals and microorganisms belonging to lower and higher taxonomic groups have been experimented for GS of MNPs, such as gold (Au), silver (Ag), copper oxide (CuO), zinc oxide (ZnO), iron (Fe2O3), palladium (Pd), platinum (Pt), nickel oxide (NiO) and magnesium oxide (MgO). Among the different plant groups used for GS, angiosperms and algae have been explored the most with great success. GS with animal-derived biomaterials, such as chitin, silk (sericin, fibroin and spider silk) or cell extract of invertebrates have also been reported. Gram positive and gram negative bacteria, different fungal species and virus particles have also shown their abilities in the reduction of metal ions. However, not a thumb rule, most of the reducing agents sourced from living world also act as capping agents and render MNPs less toxic or more biocompatible. The most unexplored area so far in GS is the mechanism studies for different natural reducing agents expect for few of them, such as tea and neem plants. This review encompasses the recent advances in the GS of MNPs using plants, animals and microorganisms and analyzes the key points and further discusses the pros and cons of GS in respect of chemical synthesis.

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Biological synthesis of metallic nanoparticles: plants, animals and microbial aspects

Well-dispersed and long-term stable carbon nanotubes/polyol dispersions were prepared by a mechanochemical approach with the aid of dispersing agent. Polyurethane (PU)-carbon nanotube nanocomposites were prepared by further in situ polymerization. Multi-walled carbon nanotubes (MWNT) can be dispersed individually. Fourier transform infrared (FTIR) spectra suggested that the addition of carbon nanotubes improved the degree of phase separation of polyurethane. Dynamic mechanical analysis (DMA) suggested that glass transition temperature (T g ) of polyurethane decreased with increasing carbon nanotube content slightly. Tensile test suggested that MWNT is more helpful to improve the modulus than single-walled carbon nanotube (SWNT), which is more favourable to improve the elongation of polyurethane. The different reinforcing effects of MWNT and SWNT on PU were correlated to the shearing thinning exponent and the shape factor of carbon nanotubes in polyol dispersion. Raman shift of SWNTs can reflect the dispersion state of SWNT in polyol or in PU, and the interaction between polymer and SWNT. Both SWNT and MWNT can improve the thermal stability of polyurethane and thermal conductivity.

Preparation and characterization of polyurethane-carbon nanotube composites

Author(s): Ahn, KH; Wu, XW; Liu, K; Chien, CL | Abstract: The effect of Fe doping (l20%) on the Mn site in the ferromagnetic ((Formula presented)) and the antiferromagnetic ((Formula presented)) phases of (Formula presented) has been studied. The same ionic radii of (Formula presented) and (Formula presented) cause no structure change in either series, yet conduction and ferromagnetism have been consistently suppressed by Fe doping. Colossal magnetoresistance has been shifted to lower temperatures, and in some cases enhanced by Fe doping. Doping with Fe bypasses the usually dominant lattice effects, but depopulates the hopping electrons and thus weakens the double exchange. © 1996 The American Physical Society.

Magnetic properties and colossal magnetoresistance of LaÑCaÖMnO3 materials doped with Fe

The high levels of H2O2 are closely associated with cancer and progressive neurodegenerative diseases, such as Parkinson’s disease. In this study, we developed a novel CuS nanoparticle-decorated reduced graphene oxide-based electrochemical biosensor for the reliable detection of H2O2. The new electrocatalyst, CuS/RGO composites was successfully prepared by heating the mixture of CuCl2 and Na2S aqueous solutions in the presence of PVP-protected graphene oxide at 180 °C. A potential application of CuS/RGO composite-modified electrode as a biosensor to monitor H2O2 has been investigated. The steady-state current response increases linearly with H2O2 concentration from 5 to 1500 μM with a fast response time of less than 2 s. The detection limit (3σ) for determination of H2O2 has been estimated to be 0.27 μM, which was lower than certain enzymes and noble metal nanomaterial-based biosensors. In addition, the study of storage time on the amperometric response of the sensor indicates super stability. Due to thes...

A facile one-pot synthesis of copper sulfide-decorated reduced graphene oxide composites for enhanced detecting of H2O2 in biological environments

Green synthesis of nanosilver as a sensor for detection of hydrogen peroxide in water

A single-step, cost-effective and eco-safe synthesis of a new class of homogeneous silver–polyaniline (PANI–Ag) core–shell nanorods is carried out via mild photolysis by ultraviolet radiation from sunlight (SUN UV-radiation). X-ray diffraction (XRD) of these core–shell nanorods gives two additional peaks from PANI centered at 2θ = 20.5° and 24. 9°. A validation of the core–shell structural information is given by transmission electron spectroscopy (TEM) whereas the tubular shape morphology is determined by scanning electron microscopy (SEM). UV-Vis. absorption shows a strong blue-shift along with photoluminescence emission. Fourier transform-infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDX) also support the core–shell formation. Thermogravimetric analysis (TGA) shows good thermal stability and allows excellent detection of hydrogen peroxide and hydrazine. The cyclic voltammetry (CV) results show excellent electro-activation, indicating its promising potential in sensing of clinical and environmental analytes.

A new class of PANI–Ag core–shell nanorods with sensing dimensions

Fe-doped nanocrystalline samples of titanium oxide have been synthesised by sol–gel route and conventional sintering process at 450°C under atmospheric conditions. These samples are characterised by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and dielectric property measurement. Samples with Fe content more than 4 mole% crystallises in rutile phase and those with less than 4 mole% crystallises in anatase phase. Nanocrystallite size has been controlled by Fe doping. Crystallite size was found to decrease with Fe concentration in the anatase phase samples whereas reverse happens in rutile phase samples of titanium oxide. There is a slight variation in numerical values of crystallite sizes measured by the two techniques: TEM and XRD peak broadening. The highest crystallite size was 86 nm in 10 mole% Fe-doped samples and the lowest 20 nm in 4 mole% Fe-doped sample. Large dispersions and anomalous values of the dielectric constant, er were observed at low f...

Dielectric properties of Fe-doped TiO2nanoparticles synthesised by sol–gel route

We have synthesized La1-xSrxMnO3 (with x=0.3, 0.33 & 0.4) perovskite nanoparticles using mild sol-gel technique at low temperature and thereby studied the effect of nanosize on magnetoresistance. These samples were characterized using TGA/DSC, XRD, TEM, FTIR and temperature dependent magnetoresistance (MR) measurements. Powder X-ray diffraction (XRD) result confirms the formation of pure crystalline phase with rhombohedral symmetry in R-3C space group. Crystallite size increases with increase in Sr concentration. TEM analysis further supports the nanosized particles in the samples which lie in the range of 20-30 nm. Fourier transform infrared (FTIR) spectroscopy shows a broad peak at 615 cm -1 for all the samples gives an evidence for the formation of metal oxygen bond organized in to MnO6 octahedral. The steep change in magnetoresistance (MR) at low field at low temperature is observed which is attributed to the alignment of the spins, while in the high field MR is due to the grain boundaries effect at low temperature. In the series studied, 33% Sr doped sample shows higher MR both at low temperature (-17.15) and room temperature (-3.07) than their counter parts. Copyright © 2012 VBRI Press.

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Low temperature synthesis and magneto resistance study of nano La 1-x Sr x MnO 3 (x = 0.3, 0.33, and 0.4) perovskites

Titanium matrix composites reinforced with (5, 10, 20) vol% (TiB + TiC) particulates were in situ synthesized using melting-investment casting method by reacting Ti with B4C powder. Their oxidation behavior was studied at 800–1000 °C in air. Formed scales consisted of transient TiO3 and stable rutile-TiO2. More dispersed (TiB + TiC) particulates had higher oxidation resistance due to strong Ti–B and Ti–C bonding which required higher activation energy for oxidation compared to Ti–Ti bonding in the matrix. However, such increment in oxidation resistance was limited by the formation of semi-protective titanium oxides, volatile B2O3, and CO2 gas. With increment of (TiB + TiC), scales progressively became thinner, thus improving scale adherence.

Poonam Yadav

Papers

Green synthesis of nanosilver as a sensor for detection of hydrogen peroxide in water

A new class of PANI–Ag core–shell nanorods with sensing dimensions

Dielectric properties of Fe-doped TiO2nanoparticles synthesised by sol–gel route

Low temperature synthesis and magneto resistance study of nano La 1-x Sr x MnO 3 (x = 0.3, 0.33, and 0.4) perovskites

Oxidation of Titanium Matrix Composites Reinforced with (TiB + TiC) Particulates