A New Method to Quantify the Swelling Properties of Polymer Beads Used in Solid Phase Peptide Synthesis (SPPS)

Abstract

The swelling properties of cross-linked polymer beads used as supports in solid phase peptide synthesis (SPPS) are important to the efficiency of the process and the purity of the product. Two of the important swelling properties are the volume to which the solid support will swell when contacted with solvent and how long the process requires to reach equilibrium [1]. If the swelling properties change at any stage, the reaction rate and ability to access every reactive site could be hampered. The swelling properties of the solid support are known to change throughout the synthesis, but an exact correlation is unknown. The technique highlighted here could be used to determine the effect of a change in the solvent concentration and the addition of an amino acid to the solid support on the swollen volume. The most obvious physical property of the solid support is the volume to which it swells when contacted with solvent. When the solid support is contacted with solvent, the solid support will swell to produce a gel phase made up of individual swollen beads. The swelling properties of the gel phase must be determined to be able to understand the process of SPPS. The gel phase must be maintained in a highly swollen state to allow the active species to diffuse to the reactive sites within the bead and to remove the by-products and excess reagents within the swollen bead [2].