2 research outputs found
Anti-Galvanic Reduction of Silver Ion on Gold and Its Role in Anisotropic Growth of Gold Nanomaterials
The role of silver ions in the seed-mediated
growth of gold nanostructures has been investigated. Silver submonolayer
or monolayer on specific facet of gold is assumed in previously suggested
mechanism owing to underpotential deposition (UPD) of silver by ascorbic
acid having weak reducing power. Silver overpotential deposition by
ascorbic acid, however, is confirmed by electrochemical stripping
voltammetry, whereas submonolayer of silver on gold is spontaneously
formed by anti-galvanic reduction in the absence of ascorbic acid.
In the presence of cetylÂtrimethylÂammonium bromide (CTAB),
silver overpotential deposition by ascorbic acid does not occur, but
submonolayer of silver is formed on gold surface. Adsorption of silver
and CTAB on gold dramatically hindered the electron transfer by the
oxidation of ascorbic acid on gold, which reduces gold ions to metallic
gold in seed-mediated growth. These results provide the evidence to
the in-depth observation of mechanism in seed-mediated growth where
the blocking effect of CTAB/AgÂ(submonolayer)/Au for oxidation of reducing
agent determine the shape and facet of gold nanomaterials
Subcellular Neural Probes from Single-Crystal Gold Nanowires
Size reduction of neural electrodes is essential for improving the functionality of neuroprosthetic devices, developing potent therapies for neurological and neurodegenerative diseases, and long-term brain–computer interfaces. Typical neural electrodes are micromanufactured devices with dimensions ranging from tens to hundreds of micrometers. Their further miniaturization is necessary to reduce local tissue damage and chronic immunological reactions of the brain. Here we report the neural electrode with subcellular dimensions based on single-crystalline gold nanowires (NWs) with a diameter of ∼100 nm. Unique mechanical and electrical properties of defect-free gold NWs enabled their implantation and recording of single neuron-activities in a live mouse brain despite a ∼50× reduction of the size compared to the closest analogues. Reduction of electrode dimensions enabled recording of neural activity with improved spatial resolution and differentiation of brain activity in response to different social situations for mice. The successful localization of the epileptic seizure center was also achieved using a multielectrode probe as a demonstration of the diagnostics potential of NW electrodes. This study demonstrated the realism of single-neuron recording using subcellular-sized electrodes that may be considered a pivotal point for use in diverse studies of chronic brain diseases