OBJECTIVE Platelet granule exocytosis serves a central role in hemostasis and thrombosis. Recently, single-cell amperometry has shown that platelet membrane fusion during granule exocytosis results in the formation of a fusion pore that subsequently expands to enable the extrusion of granule contents. However, the molecular mechanisms that control platelet fusion pore expansion and collapse are...

The aim of this study was the preparation, characterization, and application of a multi-wall carbon nanotubes-epoxy composite electrode (MWCNT-EP) with 25%, wt. MWCNTs loading for the voltammetric/amperometric determination of pentachlorophenol (PCP) in aqueous solutions. The structural and morphological aspects of the MWCNT-EP composite electrode were examined by scanning electron microscopy. ...

The time course of extrusion of the vesicular contents during exocytosis has been examined at adrenal medullary cells with carbon-fiber microelectrodes. Two electrochemical techniques were used: cyclic voltammetry and amperometry. Spikes obtained by amperometry had a faster time course than those measured by cyclic voltammetry, consistent with the different concentration profiles established by...

A study of real time biological phenomenon especially at intra-cellular levels mandates usage of nonobtrusive probing and measurement techniques. It is imperative that the phenomenon being observed should not be disturbed in its dynamics and the sensor dimensions should be small enough not to damage cellular integrity. Usage of micro needle tungsten electrode sensors and amperometry techniques ...

Portable detection and quantitation methods for Bacillus anthracis (anthrax) spores in pure culture or in environmental samples are lacking. Here, an amperometric immunoassay has been developed utilizing immunomagnetic separation to capture the spores and remove potential interferents from test samples followed by amperometric measurement on a field-portable instrument. Antibody-conjugated magn...

Electrochemical techniques are extensively used to investigate in vivo and in vitro events associated with neurotransmission, particularly dopamine (DA) transmission. In vivo amperometric measurements only concern evoked extracellular neurochemical events over short time periods independently of changes in basal release. In this context, DA release is evoked either by brief and low electrical o...

Carbon-fiber amperometry detects oxidizable molecules released by exocytosis. We extended this electrochemical technique to cells that do not normally secrete oxidizable transmitters. We incubated AtT-20 cells, pituitary gonadotropes, cultured cerebellar granule cells, and yeast with high concentrations of dopamine (DA) and observed spontaneous and evoked quantal release of DA by amperometry. T...

The quantal hypothesis states that neurotransmitter is released in discrete packages, quanta, thought to represent the neurotransmitter content of individual vesicles. If true, then vesicle size should influence quantal size. Although chromaffin cells are generally thought to have a single population of secretory vesicles, our electron microscopy analysis suggested two populations as the size d...

A novel gold nanoparticle-modified graphite pencil electrode (AuNP-GPE) is prepared just by immersing a bare GPE in AuNP solution, followed by heating for 15 min. The bare and modified GPEs are characterized by FE-SEM imaging and cyclic voltammetry. The AuNP-GPEs showed excellent electrocatalytic activities with respect to hydrazine oxidation, with good reproducibility. To reduce the quantifica...