Effect of Post-Implantation Heat Treatment Conditions on Photoluminescent Properties of Ion-Synthesized Gallium Oxide Nanocrystals.

A novel and promising way for creating nanomaterials based on gallium oxide is the ion synthesis of Ga2O3 nanocrystals in a SiO2/Si dielectric matrix. The properties of nanocrystals are determined by the conditions of ion synthesis-the parameters of ion irradiation and post-implantation heat treatment. In this work, the light-emitting properties of Ga2O3 nanocrystals were studied depending on the temperature and annealing atmosphere. It was found that annealing at a temperature of 900 °C leads to the appearance of intense luminescence with a maximum at ~480 nm caused by the recombination of donor-acceptor pairs. An increase in luminescence intensity upon annealing in an oxidizing atmosphere is shown. Based on data from photoluminescence excitation spectroscopy and high-resolution transmission electron microscopy, a hypothesis about the possibility of the participation of a quantum-size effect during radiative recombination is proposed. A mechanism for the formation of Ga2O3 nanocrystals during ion synthesis is suggested, which makes it possible to describe the change in the luminescent properties of the synthesized samples with varying conditions of post-implantation heat treatment.

Structure and Chemical Composition of Ion-Synthesized Gallium Oxide Nanocrystals in Dielectric Matrices.

The ion-beam synthesis of Ga2O3 nanocrystals in dielectric matrices on silicon is a novel and promising way for creating nanomaterials based on gallium oxide. This research studies the regularities of changes, depending on the synthesis regimes used, in the chemical composition of ion-implanted SiO2/Si and Al2O3/Si samples. It has been shown that the formation of Ga-O chemical bonds occurs even in the absence of thermal annealing. We also found the conditions of ion irradiation and annealing at which the content of oxidized gallium in the stochiometric state of Ga2O3 exceeds 90%. For this structure, the formation of Ga2O3 nanocrystalline inclusions was confirmed by transmission electron microscopy.

Ion-Beam Synthesis of Gallium Oxide Nanocrystals in a SiO2/Si Dielectric Matrix.

A new method for creating nanomaterials based on gallium oxide by ion-beam synthesis of nanocrystals of this compound in a SiO2/Si dielectric matrix has been proposed. The influence of the order of irradiation with ions of phase-forming elements (gallium and oxygen) on the chemical composition of implanted layers is reported. The separation of gallium profiles in the elemental and oxidized states is shown, even in the absence of post-implantation annealing. As a result of annealing, blue photoluminescence, associated with the recombination of donor-acceptor pairs (DAP) in Ga2O3 nanocrystals, appears in the spectrum. The structural characterization by transmission electron microscopy confirms the formation of ß-Ga2O3 nanocrystals. The obtained results open up the possibility of using nanocrystalline gallium oxide inclusions in traditional CMOS technology.

Glucagon-like peptide-1 enhances cardiac L-type Ca2+ currents via activation of the cAMP-dependent protein kinase A pathway.

BACKGROUND: Glucagon-like peptide-1 (GLP-1) is a hormone predominately synthesized and secreted by intestinal L-cells. GLP-1 modulates multiple cellular functions and its receptor agonists are now used clinically for diabetic treatment. Interestingly, preclinical and clinical evidence suggests that GLP-1 agonists produce beneficial effects on dysfunctional hearts via acting on myocardial GLP-1 receptors. As the effects of GLP-1 on myocyte electrophysiology are largely unknown, this study was to assess if GLP-1 could affect the cardiac voltage-gated L-type Ca2+ current (I(Ca)). METHODS: The whole-cell patch clamp method was used to record I(Ca) and action potentials in enzymatically isolated cardiomyocytes from adult canine left ventricles. RESULTS: Extracellular perfusion of GLP-1 (7-36 amide) at 5 nM increased I(Ca) by 23 ± 8% (p < 0.05, n = 7). Simultaneous bath perfusion of 5 nM GLP-1 plus 100 nM Exendin (9-39), a GLP-1 receptor antagonist, was unable to block the GLP-1-induced increase in I(Ca); however, the increase in I(Ca) was abolished if Exendin (9-39) was pre-applied 5 min prior to GLP-1 administration. Intracellular dialysis with a protein kinase A inhibitor also blocked the GLP-1-enhanced I(Ca). In addition, GLP-1 at 5 nM prolonged the durations of the action potentials by 128 ± 36 ms (p < 0.01) and 199 ± 76 ms (p < 0.05) at 50% and 90% repolarization (n = 6), respectively. CONCLUSIONS: Our data demonstrate that GLP-1 enhances I(Ca) in canine cardiomyocytes. The enhancement of I(Ca) is likely via the cAMP-dependent protein kinase A mechanism and may contribute, at least partially, to the prolongation of the action potential duration.

Gene printer: laser-scanning targeted transfection of cultured cardiac neonatal rat cells.

Heterogeneous gene expression in cardiac cells and tissues which requires targeted delivery of foreign DNA into selected cells or regions is needed for the development of novel therapies. Several techniques have been employed for targeted transfection, such as direct microinjection into cells or targeted electroporation. However, these techniques have limited bandwidth or spatial resolution of transfection. We aimed to develop a method for transfection of cardiac cells by means of laser-assisted optoporation using a standard confocal microscope. This technique allows for the transfection of selected cell types in the presence of other cell types as long as they are distinguishable with a microscope. This technique can work as a "gene printer" creating arbitrarily shaped areas of transfected cells.