Structural insights into peptides bound to the surface of silica nanopores.

The structure and surface functionalization of biologically relevant silica-based hybrid materials is investigated by 2D solid-state NMR techniques combined with dynamic nuclear polarization (DNP). This approach is applied to a model system of mesoporous silica, which is modified by in pore grafting of small peptides via solid phase peptide synthesis (SPPS). To prove the covalent binding of the peptides on the surface, DNP enhanced solid-state NMR is used for the detection of 15N NMR signals in natural abundance. DNP enhanced hetero-correlation experiments with frequency switched Lee-Goldburg homonuclear proton decoupling (1H-13C CP MAS FSLG HETCOR and 1H-15N CP MAS FSLG HETCOR) are performed to verify the primary structure and configuration of the synthesized peptides. 1H FSLG spectra and 1H-29Si FSLG HETCOR correlation spectra are recorded to investigate the orientation of the amino acid residues with respect to the silica surface. The combination of these NMR techniques allows detailed insights into the structure of amino acid functionalized hybrid compounds and the understanding for each synthesis step during the in pore SPPS.