Adenosine, adenosine monophosphate, and adenosine triphosphate adsorption from aqueous solutions on the surface of multiwall carbon nanotubes

Adenosine, adenosine monophosphate, and adenosine triphosphate adsorption from aqueous solutions on the surface of carbon nanotubes is studied. Adsorption isotherms are plotted and adsorption free energies, as well as areas per molecules of the adsorbates, are calculated at their concentrations in solutions of 0–10−3 mol/dm3. It is shown that the monomolecular adsorption is characterized by rather loose packing of adsorbate molecules on the nanotube surface, with the packing density increasing in the presence and upon a rise in the concentration of phosphate groups in adsorbate molecules. In the range of the polymolecular adsorption, at high adsorbate concentrations in solutions (C > (5–6) × 10−4 mol/dm3), the adsorption decreases in a series adenosine > adenosine monophosphate > adenosine triphosphate, i.e., with an increase in the solubility of the examined compounds in water.