Size-Exclusion Chromatography of Carboxyl-terminated Dendrimers as a Model for Permeation of Charged Particles into Like-Charged Cavities
In order to examine the permeation of small charged colloids into cavities of like charge, size-exclusion chromatography was carried out with carboxyl-terminated dendritic polymers on a porous glass stationary phase. Chromatographic partition coefficients KSEC were measured for solute diameters ranging from 2 to 8 nm, at neutral pH, and ionic strengths from 0.01 to 0.09 M, and were reported relative to those of noninteracting solutes of equal size (pullulan and Ficoll). The experimental results were compared to values calculated using the treatment of F. G. Smith III and W. M. Deen for charged spheres in cylindrical pores of like charge (J. Colloid Interface Sci. 78, 44 (1980); 91, 571 (1983)). The measured degrees of permeation were typically 20-100% larger than the calculated values, the discrepancies being greatest for the larger solutes at high ionic strength. It is shown that the tendency of the calculations to overestimate the repulsion are likely to arise from linearization of the Poisson-Boltzmann equation.
Shah
G
Department of Chemistry, Indiana University-Purdue University, Indianapolis, Indiana, 46202
Dubin
PL
Kaplan
JI
Newkome
GR
Moorefield
CN
Baker
GR