In situ cross-linking of the shell of self-assembled peptide nanotubes

Peptide polymer nanotubes (PPNTs) were prepared by in situ surface‐initiated atom transfer radical polymerization (ATRP) from self‐assembled cyclic peptide nanotubes. PPNT dimensions, i.e., height (i.e. diameter) and length, as derived from AFM measurements of surface‐adsorbed, dry PPNT are a function of the molar mass of the peptide‐attached polymer molecules, and the overall structure is determined by subtle interplay of peptide–peptide and polymer–polymer interactions. As shown in previous communications, a PPNT length reduction occurs with increasing grafted mass of polymer chains. The latter may be attributed to strong segment–segment interactions of the nanotube‐grafted macromolecules. Here, we introduce a possible strategy to chemically stabilize PPNT. Peptide‐polymer nanotubes are prepared by in situ cross‐linking of the polymeric shell using the bi‐functional monomer ethylene glycol dimethacrylate (EGDMA) during surface‐initiated polymerization. PEGDMA‐PPNTs were characterized with respect to chemical identity, chemical stability and structure in the dry state, using FTIR, dissolution assays, and atomic force microscope (AFM) cross‐section analysis, respectively. The use of the cross‐linkable monomer yields chemically stable rigid‐rod like hybrid materials, where the overall length of the nano‐objects remains at a constant value of about 100 nm regardless of the adsorbed mass of the nanotube‐surrounding polymer material.