Calcium binding and ionic conduction in single conical nanopores with polyacid chains: model and experiments.

6533b7d9fe1ef96bd126d684

RESEARCH PRODUCT

Calcium binding and ionic conduction in single conical nanopores with polyacid chains: model and experiments.

Mubarak Ali Patricio Ramirez Salvador Mafe Wolfgang Ensinger Javier Cervera Saima Nasir

subject

General Physics and Astronomy Ionic bonding Functionalized Dissociation (chemistry)Conical nanopore Nanoscale regions chemistry.chemical_compound Nanopores I - V curve Ionic conductivity General Materials Science Conical nanopores Phosphonate group Calcium concentration Chemistry General Engineering PH effects Partition functions Ionic channels Ion equilibrium Reversible dissociation Chemical physics Functional groups Thermodynamics Desalination membranes Ion binding Porosity Dissociation Biophysical chemistry Dissociation equilibria Inorganic chemistry chemistry.chemical_element Water filtration Calcium Ion Nernst-Planck equations Applied potentials Ion binding Carboxylation Phosphonic acids Computer Simulation Carboxylate Particle Size Controlled drug release Current voltage curve Ions Binding Sites Fixed charge density PH sensitive Carboxylic acids Desalination Phosphonic acid groups Poly acids Electric Conductivity Carboxylic acid groups Fixed Charges Nanostructures Cell membranes Current-voltage curves Models Chemical Quantum theory FISICA APLICADA Calcium Biological ion channels Calcium binding Ionic current Cytology Pore wall Statistical mechanics Acids

description

Calcium binding to fixed charge groups confined over nanoscale regions is relevant to ion equilibrium and transport in the ionic channels of the cell membranes and artificial nanopores. We present an experimental and theoretical description of the dissociation equilibrium and transport in a single conical nanopore functionalized with pH-sensitive carboxylic acid groups and phosphonic acid chains. Different phenomena are simultaneously present in this basic problem of physical and biophysical chemistry: (i) the divalent nature of the phosphonic acid groups fixed to the pore walls and the influence of the pH and calcium on the reversible dissociation equilibrium of these groups; (ii) the asymmetry of the fixed charge density; and (iii) the effects of the applied potential difference and calcium concentration on the observed ionic currents. The significant difference between the carboxylate and phosphonate groups with respect to the calcium binding is clearly observed in the corresponding current-voltage (I-V) curves and can be rationalized by using a simple molecular model based on the grand partition function formalism of statistical thermodynamics. The I-V curves of the asymmetric nanopore can be described by the Poisson and Nernst-Planck equations. The results should be of interest for the basic understanding of divalent ion binding and transport in biological ion channels, desalination membranes, and controlled drug release devices. © 2012 American Chemical Society.

year	journal	country	edition	language
2012-01-01	ACS nano

10.1021/nn303669g https://pubmed.ncbi.nlm.nih.gov/22978291