Oriented growth of metal and semiconductor nanostructures within aligned mesoporous channels

In the present work, we show how different types of inclusion chemistry can be used to generate oriented, high-aspect-ratio metal and semiconductor nanowires in insulating silica host structures prepared within anodic alumina membranes (AAMs). The structural features of the Pluronic123-templated silica filaments in the AAMs with their intriguing columnar and circular arrangement of mesopores allow for the inclusion of a variety of aligned 1D nanostructures ranging from metallic (Pt, Au, and Pd) and semiconductor (Ge) to carbon nanotubes and filaments. The synthetic techniques include wet chemical impregnation and reduction in precalcined mesopores, impregnation of surfactant-containing mesopore systems, and mass transport via supercritical fluid deposition in surfactant-containing mesopores. Important issues such as the crystallinity and continuity of the encapsulated wires as a function of material and deposition technique have been discussed

Structural Characterization of Mesoporous Silica Nanofibers Synthesized Within Porous Alumina Membranes

Mesoporous silica nanofibers were synthesized within the pores of the anodic aluminum oxide template using a simple sol–gel method. Transmission electron microscopy investigation indicated that the concentration of the structure-directing agent (EO20PO70EO20) had a significant impact on the mesostructure of mesoporous silica nanofibers. Samples with alignment of nanochannels along the axis of mesoporous silica nanofibers could be formed under the P123 concentration of 0.15 mg/mL. When the P123 concentration increased to 0.3 mg/mL, samples with a circular lamellar mesostructure could be obtained. The mechanism for the effect of the P123 concentration on the mesostructure of mesoporous silica nanofibres was proposed and discussed

Controlling interferometric properties of nanoporous anodic aluminium oxide

A study of reflective interference spectroscopy [RIfS] properties of nanoporous anodic aluminium oxide [AAO] with the aim to develop a reliable substrate for label-free optical biosensing is presented. The influence of structural parameters of AAO including pore diameters, inter-pore distance, pore length, and surface modification by deposition of Au, Ag, Cr, Pt, Ni, and TiO2 on the RIfS signal (Fabry-Perot fringe) was explored. AAO with controlled pore dimensions was prepared by electrochemical anodization of aluminium using 0.3 M oxalic acid at different voltages (30 to 70 V) and anodization times (10 to 60 min). Results show the strong influence of pore structures and surface modifications on the interference signal and indicate the importance of optimisation of AAO pore structures for RIfS sensing. The pore length/pore diameter aspect ratio of AAO was identified as a suitable parameter to tune interferometric properties of AAO. Finally, the application of AAO with optimised pore structures for sensing of a surface binding reaction of alkanethiols (mercaptoundecanoic acid) on gold surface is demonstrated

Oriented growth of metal and semiconductor nanostructures within aligned mesoporous channels

In the present work, we show how different types of inclusion chemistry can be used to generate oriented, high-aspect-ratio metal and semiconductor nanowires in insulating silica host structures prepared within anodic alumina membranes (AAMs). The structural features of the Pluronic123-templated silica filaments in the AAMs with their intriguing columnar and circular arrangement of mesopores allow for the inclusion of a variety of aligned 1D nanostructures ranging from metallic (Pt, Au, and Pd) and semiconductor (Ge) to carbon nanotubes and filaments. The synthetic techniques include wet chemical impregnation and reduction in precalcined mesopores, impregnation of surfactant-containing mesopore systems, and mass transport via supercritical fluid deposition in surfactant-containing mesopores. Important issues such as the crystallinity and continuity of the encapsulated wires as a function of material and deposition technique have been discussed

Repetitive magnetic stimulation induces plasticity of excitatory postsynapses on proximal dendrites of cultured mouse CA1 pyramidal neurons

Repetitive transcranial magnetic stimulation (rTMS) of the human brain can lead to long-lasting changes in cortical excitability. However, the cellular and molecular mechanisms which underlie rTMS-induced plasticity remain incompletely understood. Here, we used repetitive magnetic stimulation (rMS) of mouse entorhino-hippocampal slice cultures to study rMS-induced plasticity of excitatory postsynapses. By employing whole-cell patch-clamp recordings of CA1 pyramidal neurons, local electrical stimulations, immunostainings for the glutamate receptor subunit GluA1 and compartmental modeling, we found evidence for a preferential potentiation of excitatory synapses on proximal dendrites of CA1 neurons (2-4 h after stimulation). This rMS-induced synaptic potentiation required the activation of voltage-gated sodium channels, L-type voltage-gated calcium channels and N-methyl-D-aspartate-receptors. In view of these findings we propose a cellular model for the preferential strengthening of excitatory synapses on proximal dendrites following rMS in vitro, which is based on a cooperative effect of synaptic glutamatergic transmission and postsynaptic depolarization