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Multi-layer graphene oxide-enzyme nanoassemblies were prepared through the multi-point covalent immobilization of laccase from Trametes versicolor (TvL) on functionalized graphene oxide (fGO). The catalytic properties of the fGO-TvL nanoassemblies were found to depend on the number of the graphene oxide-enzyme layers present in the nanostructure. The fGO-TvL nanoassemblies exhibit an enhanced thermal stability at 60 °C, as demonstrated by a 4.7-fold higher activity as compared to the free enzyme. The multi-layer graphene oxide-enzyme nanoassemblies can efficiently catalyze the oxidation of anthracene, as well as the decolorization of an industrial dye, pinacyanol chloride. These materials retained almost completely their decolorization activity after five reaction cycles, proving their potential as efficient nano- biocatalysts for various applications.

The present study evaluates the use of thiolized chitosan conjugates (CS) in combination with two fundamental carbon nanoforms (carbon dots (CDs) and Hierarchical Porous Carbons (HPC)) for the preparation of intranasally (IN) administrated galantamine (GAL) nanoparticles (NPs). Initially, the modification of CS with L-cysteine (Cys) was performed, and the successful formation of a Cys-CS conjugates was verified via 1H-NMR, FTIR, and pXRD. The new Cys-CS conjugate showed a significant solubility enhancement in neutral and alkaline pH, improving CS's utility as a matrix-carrier for IN drug administration. In a further step, drug-loaded NPs were prepared via solid-oil–water double emulsification, and thoroughly analyzed by SEM, DLS, FTIR and pXRD. The results showed the formation of spherical NPs with a smooth surface, while the drug was amorphously dispersed within most of the prepared NPs, with the exemption of those systems contianing the CDs. Finally, in vitro dissolution release studies revealed that the prepared NPs could prolong GAL's release for up to 12 days. In sum, regarding the most promising system, the results of the present study clearly suggest that the preparation of NPs using both Cys-CS and CDs results in a more thermodynamically stable drug dispersion, while a zero-order release profile was achieved, which is essential to attain a stable in vivo pharmacokinetic behavior. [ABSTRACT FROM AUTHOR]

Carbon into polymer nanocomposite is so far a common additive for the enhancement of the polymer properties. The properties of the polymer, such as thermal, and especially its mechanical properties, are improved by the homogeneously dispersed carbon nanoparticles on the polymer matrix. In this study, carbon wires in nano dimensions are, for the very first time, synthesized via the hard templating method from the silicate matrix MCM-41, and used as nano additives of polystyrene. The carbon nanowires were chemically oxidized, and further modified by attaching octadecylamine molecules, for the development of organic functionalities onto carbon nanowires surface. The nanocomposite materials of polystyrene with the modified carbon nanowires were prepared by a solution-precipitation method at three nano additive to polymer loadings (1, 3 and 5 wt%). The as-derived nanocomposites were studied with a combination of characterization and analytical techniques. The results showed that the thermal and mechanical properties of the polystyrene nanocomposites gradually improved while increasing nano-additive loading until 3 wt%. More specifically, the 3 wt% loading sample showed the best mechanical properties, while the 5 wt% sample was difficult to achieve satisfactory dispersion of carbon nanowires and consequently has a wide range of values. [ABSTRACT FROM AUTHOR]

FePt nanoparticles have been encapsulated in insulating and protective MgO shells, using a two step chemical process, in order to prevent sintering during the heat-treatment process required for the L10 ordering. The FePt nanoparticles were initially prepared using a standard polyol process and then dispersed in a magnesium oxide solution. As a basis for comparison FePt/SiO2 nanocomposites have been also synthesized using a modified aqueous sol-gel route as the second step. The magnetic and microstructural properties of FePt/MgO and FePt/SiO2 nanocomposites are compared with those of FePt nanoparticles. The presence of oxide matrices leads to more homogeneous microstructures and better magnetic properties. While higher coercivity values have been obtained in FePt/SiO2, the MgO matrix is proven to provide better physical and magnetic isolations of the FePt nanoparticles. However, for FePt:MgO molar ratios exceeding 1:20 no L10 ordering has been achieved. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation toward methane, a reaction of high environmental and sustainable energy importance, was investigated at 200–600 °C and H2/CO2 = 4/1, over Rh nanoparticles dispersed on supports with different oxygen storage capacity characteristics (γ-Al2O3, alumina-ceria-zirconia, and ceria-zirconia). The effects of the support OSC and Rh particle size on reaction behavior under both integral and differential conditions were investigated, to elucidate the combined role of these crucial catalyst design parameters on methanation efficiency. A volcano-type variation of methanation turnover frequency was found in respect to support OSC; Rh/ACZ, with intermediate OSC, was the optimal catalyst. The structure sensitivity of the reaction was found to be a combined function of support OSC and Rh particle size: For Rh/γ-Al2O3 (lack of OSC) methanation was strongly favored on small particles—the opposite for Rh/CZ (high OSC). The findings are promising for rational design and optimization of CO2 methanation catalysts by tailoring the aforementioned characteristics. [ABSTRACT FROM AUTHOR]

In the present study, poly(l-lactic acid) (PLLA) and poly(lactide-co-glycolide) (PLGA) hybrid nanoparticles were developed for intranasal delivery of galantamine, a drug used in severe to moderate cases of Alzheimer's disease. Galantamine (GAL) was adsorbed first in hierarchical porous carbon (HPC). Formulations were characterized by FT-IR, which showed hydrogen bond formation between GAL and HPC. Furthermore, GAL became amorphous after adsorption, as confirmed by XRD and differential scanning calorimetry (DSC) studies. GAL was quantified to be 21.5% w/w by TGA study. Adsorbed GAL was nanoencapsulated in PLLA and PLGA, and prepared nanoparticles were characterized by several techniques. Their sizes varied between 182 and 394 nm, with an exception that was observed in nanoparticles that were prepared by PLLA and adsorbed GAL that was found to be 1302 nm in size. DSC thermographs showed that GAL was present in its crystalline state in nanoparticles before its adsorption to HPC, while it remained in its amorphous phase after its adsorption in the prepared nanoparticles. It was found that the polymers controlled the release of GAL both when it was encapsulated alone and when it was adsorbed on HPC. Lastly, PLGA hybrid nanoparticles were intranasally-administered in healthy, adult, male Wistar rats. Administration led to successful delivery to the hippocampus, the brain area that is primarily and severely harmed in Alzheimer's disease, just a few hours after a single dose. [ABSTRACT FROM AUTHOR]

This work reports a new approach for the determination of phenolic compounds based on their interaction with citrate-capped rhodium nanoparticles. Phenolic compounds (i.e., catechins, gallates, cinnamates, and dihydroxybenzoic acids) were found to cause changes in the size and localized surface plasmon resonance of rhodium nanoparticles, and therefore, give rise to analyte-specific spectral and color transitions in the rhodium nanoparticle suspensions. Upon reaction with phenolic compounds (mainly dithydroxybenzoate derivatives, and trihydroxybenzoate derivatives), new absorbance peaks at 350 nm and 450 nm were observed. Upon reaction with trihydroxybenzoate derivatives, however, an additional absorbance peak at 580 nm was observed facilitating the speciation of phenolic compounds in the sample. Both absorbance peaks at 450 nm and 580 nm increased with increasing concentration of phenolic compounds over a linear range of 0–500 μM. Detection limits at the mid-micromolar levels were achieved, depending on the phenolic compound involved, and with satisfactory reproducibility (<7.3%). On the basis of these findings, two rhodium nanoparticles-based assays for the determination of the total phenolic content and total catechin content were developed and applied in tea samples. The obtained results correlated favorably with commonly used methods (i.e., Folin-Ciocalteu and aluminum complexation assay). Not the least, the finding that rhodium nanoparticles can react with analytes and exhibit unique localized surface plasmon resonance bands in the visible region, can open new opportunities for developing new optical and sensing analytical applications. [ABSTRACT FROM AUTHOR]

A drug delivery nanosystem of noble bimetallic nanoparticles (NPs) which consists of Au NPs capped with Pt NPs (Au@Pt NPs) is constructed and functionalised with a quinazoline based small molecule (Au@Pt@Q NPs), acting as a theranostic agent against glioblastoma. Two different hydrothermal synthetic procedures for bimetallic Au@Pt NPs are presented and the resulting nanostructures are fully characterised by means of spectroscopic and microscopic methods. The imaging and targeting capacity of the new drug delivery system is assessed through fluorescent optical microscopy and cytotoxicity evaluations. The constructed Au@Pt NPs consist a monodispersed colloidal solution of 25 nm with photoluminescent, fluorescent and X-Ray absorption properties that confirm their diagnostic potential. Haemolysis testing demonstrated that Au@Pt NPs are biocompatible and fluorescent microscopy confirmed their entering the cells. Cytological evaluation of the NPs through MTT assay showed that they do not inhibit the proliferation of control cell line HEK293, whereas they are toxic in U87MG, U251 and D54 glioblastoma cell lines; rendering them selective targeting agents for treating glioblastoma. [Display omitted] • Au NPs capped with Pt NPs; conjugation of small organic molecule. • Auto-fluorescent; auto-photoluminescent; auto-X-Ray absorption. • Selective targeting of glioblastoma cell lines. • Negligible toxicity at non-cancerous cell line. [ABSTRACT FROM AUTHOR]

Abstract: Novel hybrid electrocatalysts were developed based on the attachment of pre-formed capped Pt and PtRu nanoparticles (NPs) on the external surfaces of multi-walled carbon nanotubes (MWCNTs). MWCNTs chemically functionalized by both covalent and non-covalent chemical strategies were tested and evaluated as nanotemplates for the dispersion and stabilization of NPs. The suitable functionalized MWCNTs derivatives were then reacted with pre-formed capped Pt and PtRu NPs yielding the final hybrid materials. The intermediate products as well as the final hybrid materials were characterized in detail with a combination of experimental techniques including Raman spectroscopy, X-ray diffraction, scanning and transmission electron microscopy, while comparative studies regarding their electrocatalytic performance to the oxidation of methanol and ammonia, and to the reduction of hydrogen peroxide were made by performing cyclic voltammetry studies. The results revealed the uniform dispersion of very small NPs along the external surface of functionalized CNTs, while the most suitable electrocatalyst for each particular application is indicated. The chemical strategy followed for the surface functionalization of MWCNTs seems to greatly influence the catalytic activity of the resulting hybrids materials. [Copyright &y& Elsevier]