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In this paper we demonstrate a potentiostat built with a single commercially available integrated circuit (IC) that does not require any external electronic components to perform electrochemical experiments. This is done using the capabilities of the Programmable System on a Chip (PSoC®) by Cypress Semiconductor, which integrates all of the necessary electrical components. This is in contrast to other recent papers that have developed potentiostats but require technical skills or specialized equipment to produce. This eliminates the process of having to make a printed circuit board and soldering on electronic components. To control the device, a graphical user interface (GUI) was developed in the python programming language. Python is open source, with a style that makes it easy to read and write programs, making it an ideal choice for open source projects. As the developed device is open source and based on a PSoC, modification to implement other electrochemical techniques is straightforward and only requires modest programming skills, but no expensive equipment or difficult techniques. The potentiostat developed here adds to the growing amount of open source laboratory equipment. To demonstrate the PSoC potentiostat in a wide range of applications, we performed cyclic voltammetry (to measure vitamin C concentration in orange juice), amperometry (to measure glucose with a glucose strip), and stripping voltammetry experiments (to measure lead in water). The device was able to perform all experiments and could accurately measure Vitamin C, glucose, and lead. [ABSTRACT FROM AUTHOR]

We explored the ability of a two-site, three-barrier (2S3B) Eyring model to describe recently reported data on current flow through open Ca(V)3.1 T-type calcium channels, varying Ca(2+) and Ba(2+) over a wide range (100 nM: -110 mM: ) while recording whole-cell currents over a wide voltage range (-150 mV to +100 mV) from channels stably expressed in HEK 293 cells. Effects on permeation were isolated using instantaneous current-voltage relationships (IIV) after strong, brief depolarizations to activate channels with minimal inactivation. Most experimental results were reproduced by a 2S3B model. The model described the IIV relationships, apparent affinities for permeation and block for Ca(2+) and Ba(2+), and shifts in reversal potential between Ca(2+) and Ba(2+). The fit to block by 1 mM Mg(2+)(i) was reasonable, but block by Mg(2+)(0) was described less well. Surprisingly, fits were comparable with strong ion-ion repulsion, with no repulsion, or with intermediate values. With weak repulsion, there was a single high-affinity site, with a low-affinity site near the cytoplasmic side of the pore. With strong repulsion, the net charge of ions in the pore was near +2 over a relatively wide range of concentration and voltage, suggesting a knockoff mechanism. With strong repulsion, Ba(2+) preferred the inner site, while Ca(2+) preferred the outer site, potentially explaining faster entry of Ni(2+) and other pore blockers when Ba(2+) is the charge carrier. [ABSTRACT FROM AUTHOR]