Search results for "Ph sensing"
showing 3 items of 3 documents
Experimental and theoretical studies on electropolymerization of polar amino acids on platinum electrode
2017
International audience; The anodic oxidation of polar amino acids (L-serine, L-threonine, L-asparagine, and L-glutamine) in aqueous electrolyte on smooth platinum electrode was carried out by cyclic voltammetry coupled to electrochemical quartz crystal microbalance (EQCM). pH (zwitterion, acidic and alkaline) effects on their electrochemical behavior were examined. The maximum current values are measured for zwitterion species. In addition, the current increases with increasing of concentration and scan rate, and decreases with increasing pH. The resulting passivation was studied by spectroscopic analysis such as attenuated total reflection FT infrared spectroscopy (ATR-FTIR), X-ray photoel…
Entropy–enthalpy compensation at the single protein level: pH sensing in the bacterial channel OmpF
2014
The pH sensing mechanism of the OmpF channel operates via ligand modification: increasing acidity induces the replacement of cations with protons in critical binding sites decreasing the channel conductance. Aside from the change in enthalpy associated with the binding, there is also a change in the microscopic arrangements of ligands, receptors and the surrounding solvent. We show that the pH-modulation of the single channel conduction involves small free energy changes because large enthalpic and entropic contributions change in opposite ways, demonstrating an approximate enthalpy–entropy compensation for different salts and concentrations. We wish to acknowledge the support from the Span…
Net currents obtained from zero-average potentials in single amphoteric nanopores
2013
We have studied experimentally and theoretically the rectifying properties of a single asymmetric nanopore functionalized with amphoteric lysine groups and characterized the net current obtained with zero-average time dependent potentials. The pH-controlled rectification phenomena may be relevant to bio-electrochemistry, pH sensing and regulation, and energy conversion. (C) 2013 Elsevier B.V. All rights reserved.