Recombinant Protein Immobilization and Controlled-Release Mediated by a Non-Covalent Protein Anchor

Immobilization of chemically complex molecules such as protein has been a challenge for a variety of fields including drug delivery. Traditional immobilization strategies that utilize covalent modifications are prone to causing loss of protein function and/or aggregation because they often disrupt the active sites and/or folded structure of the protein molecule. Non-covalent protein immobilization strategies can prevent disruption of amino acids on the protein molecule that affect activity or folded structure. We used the natural affinity between glutathione S-transferase (GST) and glutathione (GSH) to immobilize recombinant protein to the surface of poly(ethylene-glycol) diacrylate (PEGDA) microspheres. The GST/GSH immobilization strategy proved stable in extracellular environments and functional macromolecular cargo could be released from the surface of the PEGDA microspheres by enzyme catalyzed proteolysis. Environments with activated proteolytic enzymes are common in several disease states including bacteremia, cancer, wound healing, and venous thrombosis. Due to the ease of creation, and the already high numbers of proteins being purified with GST fusion anchors, we believe the GST/GSH anchor to be a promising component of future protein delivery systems.