Enhanced photoluminescence of Gd2O3:Eu3+ nanophosphors with alkali (M = Li+, Na+, K+) metal ion co-doping

Gd1.95Eu0.4M0.01O3 (M = Li+ Na+ K+) nanophosphors have been synthesized by a low temperature solution combustion (LSC) method. Powder X-ray diffraction pattern (PXRD), scanning electron microscopy (SEM), UV-vis and photoluminescence (PL) measurements were carried out to characterize their structural and luminescent properties. The excitation and emission spectra indicated that the phosphor could be well excited by UV light (243 nm) and emit red light about 612 nm. The effect of alkali co-dopant on PL properties has been examined. The results showed that incorporation of Li+, Na+ and K+ in to Gd2O3:Eu3+ phosphor would lead to a remarkable increase of photoluminescence. The PL intensity of Gd2O3:Eu3+ phosphor was improved evidently by co-doping with Li+ ions whose radius is less than that of Gd3+ and hardly with Na+, K+ whose radius is larger than that of Gd3+. The effect of co-dopants on enhanced luminescence was mainly regarded as the result of a suitable local distortion of crystal field surrounding the Eu3+ activator. These results will play an important role in seeking some more effective co-dopants. (C) 2011 Published by Elsevier B.V.

Synthesis of free standing carbon nanosheet using electron cyclotron resonance plasma enhanced chemical vapor deposition

Carbon nanosheets (CNSs) have been synthesized by electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (PECVD) using a mixture of acetylene and argon gases on copper foil as the substrate. Micrometer-wide carbon sheets consisting of several atomic layers thick graphene sheets have been synthesized by controlled decomposition of carbon radicals in ECR-PECVD. Raman spectroscopy of these films revealed characteristics of a disordered graphitic sheet. Thick folded carbon-sheets and a semi transparent freestanding CNSs have been observed by scanning electron microscopy. This is a promising technique to synthesize free standing CNSs and can be used in the fabrication of nanoelecronic devices in future. (C) 2012 Elsevier B.V. All rights reserved.

Layer-by-Layer Assembled Thin Film of Albumin Nanoparticles for Delivery of Doxorubicin

Protein nanoparticles (NPs) have found significant applications in drug delivery due to their inherent biocompatibility, which is attributed to their natural origin. In this study, bovine serum abumin (BSA) nanoparticles were introduced in multilayer thin film via layer-by-layer self-assembly for localized delivery of the anticancer drug Doxorubicin (Dox). BSA nanoparticles (similar to 100 nm) show a high negative zeta potential in aqueous medium (-55 mV) and form a stable dispersion in water without agglomeration for a long period. Hence, BSA NPs can be assembled on a substrate via layer-by-layer approach using a positively charged polyelectrolyte (chitosan in acidic medium). The protein nature of these BSA nanoparticles ensures the biocompatibility of the film, whereas the availability of functional groups on this protein allows one to tune the property of the self-assembly to have a pH-dependent drug release profile. The growth of multilayer thin film was monitored by UV-visible spectroscopy, and the films were further characterized by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The drug release kinetics of these BSA nanoparticles and their self-assembled thin film has been compared at a physiological pH of 7.4 and an acidic pH of 6.4.