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One-step chemical reduction approach is developed to synthesize nearly monodispersed Ag–Au alloy nanoparticles stabilized by CTAB molecules. By controlling the molar ratios of Ag(I) and Au(III), the surface plasmon resonance (SPR) band of alloy nanoparticles observe between 410 and 530 nm, which are the absorption maxima of silver and gold nanoparticles, respectively. The transmission electron microscope (TEM) shows that the obtained alloy nanoparticles are spherical in shape having size from 12 to 17 nm which provides high catalytic activity towards hydrogenation reactions. The catalytic efficiency of Ag NPs are less compared to pure Au NPs, whereas their activity can be modulated in between these two by appropriately controlling their molar ratio in the resultant Ag–Au alloy NPs. Moreover, with regards to high stability and recyclability, Ag–Au alloy NPs shows ~ 100% conversion efficiency up to five consecutive reaction cycles while monometallic nanoparticle are incapable. Thus, it is possible to modulate and enhance the catalytic activity of Ag NPs by making an alloy with Au NPs of desired composition.

Huma Rizwan,1 Jagdeep Mohanta,2 Satyabrata Si,1,2 Arttatrana Pal3 1School of Biotechnology, KIIT University, Bhubaneswar, India; 2School of Applied Sciences, KIIT University, Bhubaneswar, India; 3Department of Zoology, School of Life Sciences, Mahatma Gandhi Central University, Bihar, India Abstract: Hyperglycemia is a risk factor for cardiovascular mortality and morbidity, and directly responsible for exacerbating macrophage activation and atherosclerosis. We showed that gold nanoparticles (AuNPs) reduce the high glucose (HG)-induced atherosclerosis-related complications in macrophages via oxidative-nitrosative stress-regulated inflammation and apoptosis. The effects of AuNPs on oxidative-nitrosative stress markers such as cellular antioxidants were attenuated by HG exposure, leading to reduction in the accumulation of reactive oxygen/nitrogen species in cellular compartments. Further, these abnormalities of antioxidants level and reactive oxygen/nitrogen species accumulations initiate cellular stress, resulting in the activation of nuclear factor κB (NF-κB) via ERK1/2mitogen-activated protein kinase (MAPK)/Akt/tuberin- mammalian target of rapamycin (mTOR) pathways. The activated NF-κB stimulates inflammatory mediators, which subsequently subdue biomolecules damage, leading to aggravation of the inflammatory infiltration and immune responses. Treatment of AuNPs inhibits the intracellular redox-sensitive signaling pathways, inflammation, and apoptosis in macrophages. Together, our results indicate that AuNPs may modulate HG-induced oxidative-nitrosative stress. These effects may be sealed tight due to the fact that AuNPs treatment reduces the activation of NF-κB by ERK1/2MAPK/Akt/tuberin-mTOR pathways-mediated inflammatory genes expression and cellular stress responses, which may be beneficial for minimizing the atherosclerosis. Keywords: gold nanoparticles, oxidative-nitrosative stress, apoptosis, macrophages, atherosclerosis&nbsp

The present work describes the catalytic activity of gold nanoparticles towards the reduction of 4-nitrophenol and their modulation through surface tailoring using various organic ligands. One step protocol is used to prepare CTAB capped gold nanoparticles of size 15 ± 2 nm and the catalysis reaction using these particles simultaneously follow both zero-order and first-order reaction kinetics. The zero-order rate constant, k0=0.418 mol lit−1 min−1 and first-order rate constant, k1=0.938 min−1 is achieved just by using 8 nM of gold catalyst. On the other hand citrate capped gold nanoparticles of similar sizes (13 ± 3 nm) follow only the first-order kinetics with k1=0.243 min−1, which is about four times less compared to CTAB capped gold nanoparticles. Moreover, the reaction kinetics is changed to zero-order rate with k0=0.345 mol lit−1 min−1 simply by replacing citrate with CTAB on the gold nanoparticles surface. On the other hand, replacing the citrate with PVP on the nanoparticles surface, the reaction rate still follows the first-order kinetics, but with two-fold increase in the rate constant with k1=0.587 min−1. Further, silica coating of the CTAB capped gold nanoparticles and their use as catalyst for 4-nitrphenol reduction exclusively follows the zero-order kinetics with k0=0.305 mol lit−1 min−1 and are better recyclable upto five cycles without affecting their conversion efficiency.

The successful coating of thin porous silica layers of various thicknesses [(10±1), (12±1), and (14±1) nm] on cetyl trimethylammonium bromide (CTAB) capped gold nanorods was achieved through a modified Stöber procedure. The resulting material was applied as a novel catalyst for the reduction of 4-nitrophenol. The catalytic activities of the gold nanorods increased up to eight times after coating with a layer of porous silica and the reaction followed a zero-order kinetics, having a rate constant as high as 2.92×10(-1) mol L(-1) min(-1). The spectral changes during the reduction reaction of 4-nitrophenol were observed within a very short span of time and a complete conversion to 4-aminophenol occured within 5-6 mins, including the induction period of ≈2 mins. The reusability of the catalyst was studied by running the catalytic reaction during five consecutive cycles with good efficiency without destroying the nanostructure. The methodology can be effectively applied to the development of composite catalysts with highly enhanced catalytic activity.

The present work describes the synthesis of some poly(ethylene oxide)-based nanocomposite polymer electrolyte films using various silica nanostructures as the inorganic filler by simple solution mixing technique, in which the nature of the silica nanostructures play a vital role in modulating their electrochemical performances at room temperature. The silica nanostructures are prepared by ammonical hydrolysis of tetraethyl orthosilicate following the modified St6ber method. The resulting films are characterized by X-ray diffraction and differential scanning calorimeter to study their crystallinity. Room temperature AC impedance spectroscopy is utilized to determine the Li+ ion conductivity of the resulting films. The observed conductivity values of various NCPE films depend on the nature of silica filling as well as on their surface characteristics and also on the varying PEO-Li+ ratio, which is observed to be in the order of 10(-7)-10(-6) S cm(-1).

is an allotrope of carbon which is the basic structural unit of other allotropic forms of carbon, viz., graphite, carbon nanotubes and fullerenes. Structurally, it is a �耀at monolayer of carbon atoms with honeycomb lattice, which can be wrapped up into 0D fullerenes, rolled into 1D nanotubes or stacked into 3D graphite. �怀e 2010 Nobel Prize in Physics was jointly awarded to Andre Geim and Konstantin Novoselov for their revolutionary work on graphene, which implies its potential impact in future nanotechnology. Graphene is known to be a zero bandgap semiconductor material, therefore the Fermi level can be altered to form n-doped or p-doped material through simple physicochemical processes. Owing to its interesting properties, graphene is being used in various applications including supercapacitors, transistors, electrode materials, display screens, chemical sensors, membranes, etc. �怀e present review highlights the various synthetic strategies, fundamental properties and their potential techno- logical application.

Optimal single particle tracking experiments in live cells requires small and photostable probes, which do not modify the behavior of the molecule of interest. Current fluorescence-based microscopy of single molecules and nanoparticles is often limited by bleaching and blinking or by the probe size. As an alternative, we present in this chapter the synthesis of a small and highly specific gold nanoprobe whose detection is based on its absorption properties. We first present a protocol to synthesize 5-nm-diameter gold nanoparticles and functionalize them with a nanobody, a single-domain antibody from camelid, targeting the widespread green fluorescent protein (GFP)-tagged proteins with a high affinity. Then we describe how to detect and track these individual gold nanoparticles in live cell using photothermal imaging microscopy. The combination of a probe with small size, perfect photostability, high specificity, and versatility through the vast existing library of GFP-proteins, with a highly sensitive detection technique enables long-term tracking of proteins with minimal hindrance in confined and crowded environments such as intracellular space.

The current study represents the design and synthesis of polyethylene oxide (PEO)-based solid polymer electrolytes by solvent casting approach using surface tailored porous silica as nanofillers. The surface tailoring of porous silica nanostructure is achieved through silanization chemistry using 3-glycidyloxypropyl trimethoxysilane in which silane part get anchored to the silica surface whereas epoxy group get stellated from the silica surface. Surface tailoring of silica with epoxy group increases the room temperature electrochemical performances of the resulting polymer electrolytes. Ammonical hydrolysis of organosilicate precursor is used for both silica preparation and their surface tailoring. The composite solid polymer electrolyte films are prepared by solution mixing of PEO with lithium salt in presence of silica nanofillers and cast into film by solvent drying, which are then characterized by impedance measurement for conductivity study and wide angle x-ray diffraction for change in polymer crystallinity. Room temperature impedance measurement reveals Li+ ion conductivity in the order of 10−4 S cm−1, which is correlated to the decrease in PEO crystallinity. The enhancement of conductivity is further observed to be dependent on the amount of silica as well as on their surface characteristics.