Low-Loaded Polyethylene Glycol (PEG) Resin for High-Purity Peptide Synthesis and Cell Binding Assays

In solid-phase peptide synthesis (SPPS), a high concentration of functional groups on the solid support and an adequate swelling volume enables its use for high-throughput screening of receptor agonists and therapeutic peptides. However, a high resin loading often leads to insufficient purity of the synthesized peptides and false positive binding with the target due to improper interactions between neighboring peptides. Therefore, this study focused on low-loaded polyethylene glycol (PEG) resins to achieve high-specificity screening using a core–shell-type PEG hydrogel resin. The peptide purity and target specificity were determined by assessing (1) the resin swelling properties in various solvents, (2) purity of a complicated Jung-Redemann (JR) decapeptide, and (3) the cell-adhesive behavior of GRGDS-pentapeptide-bound resins. The results were compared with those obtained using polyacrylamide resin (PAM) and conventionally used TentaGel S NH₂ resin (TG ^®). The highest JR decapeptide purity was achieved using the PEG-based resin with a higher degree of cross-linking (PEGHN). Furthermore, the resin was preferably qualified as an extracellular microenvironment to accommodate true specific binding with fibroblast cells. Thus, SPPS and cell binding assays using the developed PEG-based resin provide a novel stringent strategy with potential application for true positive screening in biological assays.