Emulsion-templated synthetic polypeptide scaffolds prepared by ring-opening polymerization of N-carboxyanhydrides

Abstract

Unique morphology of scaffolds prepared by high internal phase emulsion (HIPE) templating is extremely attractive for tissue engineering purposes. However, the synthetic approaches in HIPE are mainly limited to the preparation of either nondegradable polymers or polyesters lacking the pendant functionality. In order to prepare functional scaffolds capable of providing a suitable micro-environment for cell growth, we have developed a method for the preparation of emulsion-templated polypeptide scaffolds, where ring-opening polymerization (ROP) of N-carboxyanhydrides (NCA) of amino acids is performed directly in the oil-in-oil HIPE. Such previously unreported combination of HIPE templating and ROP of NCA requires controlled experimental conditions to ensure gelation of the system before the emulsion phase separates. At the same time, foaming of the scaffold due to CO₂ evolution during polymerization has been successfully prevented. The disclosed method was applied for the preparation of γ-benzyl-L-glutamate (BLG) and/or N^ε-carbobenzyloxy-L-lysine-based polyHIPE scaffolds crosslinked with L-cystine. Cell culture studies reveal good viability, migration, and proliferation of cells on PBLG polyHIPE. The disclosed method thus represents an attractive approach for the preparation of polyHIPE scaffolds composed entirely of synthetic polypeptides, indicating the applicability of the synthetic method to various NCA monomers for tuning the chemical composition of the scaffolds.