Effect of solvent on the charging mechanisms of XXXX in droplets.

@entity1042 @entity1372 @entity970 @entity968
We examine the effect of solvent on the charging mechanisms of a macromolecule in a droplet by using molecular dynamics simulations. The droplet contains excess charge that is carried by @entity1372 ions. To investigate the principles of the charging mechanisms of a macromolecule in a droplet, we simulate aqueous and @entity1042 droplets that contain a @entity968 ( @entity970 ) molecule. We find that the solvent plays a critical role in the charging mechanism and in the manner that the sodiated @entity970 emerges from a droplet. In the aqueous droplets, the sodiated @entity970 is released from the droplet while it is being charged at a droplet charge state below the Rayleigh limit. The charging of @entity970 occurs on the surface of the droplet. In contrast to the aqueous droplets, in the @entity1042 droplet, the sodiated @entity970 resides in the interior of the droplet and it may become charged at any location in the droplet, interior or surface. The sodiated @entity970 emerges from the droplet by drying-out of the solvent. Even though these two mechanisms appear to be phenomenologically similar to the widely accepted ion-evaporation and charge-residue mechanisms, they have fundamental differences from those. An integral part of the mechanism that the macromolecular ions emerge from droplets is the droplet morphology. Droplet morphologies give rise to different solvation interactions between the solvent and the macromolecule. In the water-sodiated @entity970 system, we find the extrusion of the @entity970 morphology, while in @entity1042 -sodiated droplet, we find the "pearl-on-the-necklace" morphology and the extrusion of the sodiated @entity970 in the last stage of the desolvation process. These findings provide insight into the mechanisms that macromolecules acquire their charge in droplets produced in electrospray ionization experiments.
