Synthesis and solid state NMR characterization of novel peptide/silica hybrid materials

- Collagen-type nonapeptide H-(Gly-Pro-Hyp)3-OH immobilized on mesoporous silica.
- DNP allows natural abundance 15N CP-MAS.
- 15N CP-MAS NMR spectroscopy proves covalent binding of peptide to silica surfaces.

The successful synthesis and solid state NMR characterization of silica-based organic-inorganic hybrid materials is presented. For this, collagen-like peptides are immobilized on carboxylate functionalized mesoporous silica (COOH/SiOx) materials. A pre-activation of the silica material with TSTU (O-(N-Succinimidyl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate) is performed to enable a covalent binding of the peptides to the linker. The success of the covalent immobilization is indicated by the decrease of the 13C CP-MAS NMR signal of the TSTU moiety. A qualitative distinction between covalently bound and adsorbed peptide is feasible by 15N CP-MAS Dynamic Nuclear Polarization (DNP). The low-field shift of the 15N signal of the peptide's N-terminus clearly identifies it as the binding site. The DNP enhancement allows the probing of natural abundance 15N nuclei, rendering expensive labeling of peptides unnecessary.