Minimally invasive manipulation of cell signaling is critical in basic neuroscience research and in developing therapies for neurological disorders. Here, a wireless chemomagnetic neuromodulation platform for the on-demand control of primary striatal neurons that relies on nanoscale heating events is described. Iron oxide magnetic nanoparticles (MNPs) are functionally coated with thermoresponsive poly (oligo (ethylene glycol) methyl ether methacrylate) (POEGMA) brushes loaded with dopamine. Dopamine loaded MNPs-POEGMA are co-cultured with primary striatal neurons. When alternating magnetic fields (AMF) are applied, MNPs undergo hysteresis power loss and dissipate heat. The local heat produced by MNPs initiates a thermodynamic phase transition on POEGMA brushes resulting in polymer collapse and dopamine release. AMF-triggered dopamine release enhances the response of dopamine ion channels expressed on the cell membranes enhancing the activity ≈50% of striatal neurons subjected to the treatment. Chemomagnetic actuation on dopamine receptors is confirmed by blocking D 1 and D 2 receptors. The reversible thermodynamic phase transition of POEGMA brushes allow the on-demand release of dopamine in multiple microdoses. AMF-triggered dopamine release from MNPs-POEGMA causes neither cell cytotoxicity nor promotes cell reactive oxygen species production. This research represents a fundamental step forward for the chemomagnetic control of neural activity using hybrid magnetic nanomaterials with tailored physical properties.
Hydrogenated microcrystalline silicon (µc-Si:H) and epitaxial silicon (epi-Si) films have been produced from SiF4, H2 and Ar mixtures by plasma enhanced chemical vapor deposition (PECVD) at 200 °C. Here, both films were produced using identical deposition conditions, to determine if the conditions for producing µc-Si with the largest crystalline fraction (XC), will also result in epi-Si films that encompass the best quality and largest crystalline silicon (c-Si) fraction. Both characteristics are of importance for the development of thin film transistors (TFTs), thin film solar cells and novel 3D devices since epi-Si films can be grown or etched in a selective manner. Therefore, we have distinguished that the H2/SiF4 ratio affects the XC of µc-Si, the c-Si fraction in epi-Si films, and the structure of the epi-Si/c-Si interface. Raman and UV-Vis ellipsometry were used to evaluate the crystalline volume fraction (Xc) and composition of the deposited layers, while the structure of the films were inspected by high resolution transmission electron microscopy (HRTEM). Notably, the conditions for producing µc-Si with the largest XC are different in comparison to the fabrication conditions of epi-Si films with the best quality and largest c-Si fraction.
Nanowires (Nws) are 1D nanostructures in which there is a preferential direction of growth-leading to an aspect ratio greater than 10. Due to the quantum confinement effects of the 1D morphology and the large surface to volume ratio, Nws are promising materials for the fabrication of high-performance photodetectors, [1] supercapacitors, [2] fuel cell materials, [3] high-performance photoswitches, [4] and nanophotonics devices. [5] In particular, magnetic Nws are of more technological interest than other magnetic nanostructured materials [6] due to their higher multifunctional properties. For example, magnetic Nws have shown potential in bioengineering, [7] wireless magnetic manipulation, [8] magnetically powered adaptive Nw swimmers, [9] and spintronics. [10] Additional applications involve the design of new nanofabrication [11] and assembly [12] methods for understanding the magnetoresistance, [13] magnetoreactance, [14] and magnetization of individual Nws. [15]
The miniaturization of magnetic components down to the nanoscale has generated significant progress in expanding magnetic nanostructures into three dimensions. However, the fabrication methods currently employed are limited by the...
Nickel nanorods (NRs) capped with gold (Au/Ni) were grown into porous anodic aluminum oxide templates and subsequently transferred onto Au/Si (100) substrates. A high dense 2D array of Ni and Au/Ni nanorods was analyzed by vibrating sample magnetometry; it was found that an increase in 14.8% of the magnetic moment following the deposition of Au caps. In order to further investigate this phenomenon, the magnetic distribution of Au/Ni nanorods was studied by off-axis electron holography. The magnetization and induction strengths were evaluated to be 4.7 × 105 A/m and 0.62 T, respectively, which is equivalent to magnetometry measurements of the Ni NR arrays. Remarkably, a vortex state configuration was imaged in the Au segment by the retrieved magnetic phase of the electron holograms under free lens conditions of the transmission electron microscope column. It was concluded that the magnetic distribution in the Au segment is associated with a ferromagnetic coupling with Ni and correlated with the magnetometry measurements.
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