Green Resins for All: Sustainable Preparation of PEGA Resin for Peptide and Protein Synthesis and Immobilization

Polyethylene glycol-polyacrylamide (PEGA) resins, known for their superior performance in peptide assembly and for their properties in on-bead biochemical assays, are, despite their superior performance, currently not commercially available. This may be due to the reported polymerization medium, CCl₄, being classified as a highly controlled substance. The present work describes the easy preparation of larger volumes of PEGA supports by either bulk inverse suspension polymerization or by size-controlled flow synthesis. The technology uses silicone oil as a suspension medium and the oil is readily recycled, leading to very little waste from the process. The suspension polymerization was performed on a 0.7 L scale of resin featuring a loading of 0.27 μmol/mL (0.39 mmol/g), providing beaded resin in the size range of 200-400 μm, sufficient for >500 peptide assemblies at 100 mg scale of medium-sized peptides. In the flow synthesis, droplets formed in a T-connector were polymerized in a heated coiled poly(tetrafluoroethylene) tubing and collected on a filter, significantly increasing the control of bead size and reducing the required amount of silicone oil employed. These beaded resins are spectroscopically transparent and act as stealth polymers that do not interact with peptides, biomolecules, or cells. Furthermore, flow synthesis provided evenly sized beads facilitating quantitative on-bead bioassays. The resin produced was used for peptide assembly and immobilization of green fluorescent protein, demonstrating uniform protein attachment throughout the beads.