Structural Insights into Peptides Bound to the Surface of Silica Nanopores

Abstract

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

Gulliver in the Country of Lilliput

“…As mentioned above these mesoporous silica materials permit the comparatively simple synthesis of surface functionalized host systems with well-defined tunable narrow pore diameters [175][176][177][178], employing a synthesis protocol, which is based on Grünberg et al [106] and Grün et al [179]. Details of the synthesis and characterization are given in [176,180] and will not be repeated here.…”

Small Molecules, Non-Covalent Interactions, and Confinement

“…As mentioned above these mesoporous silica materials permit the comparatively simple synthesis of surface functionalized host systems with well-defined tunable narrow pore diameters [ 175 , 176 , 177 , 178 ], employing a synthesis protocol, which is based on Grünberg et al [ 106 ] and Grün et al [ 179 ]. Details of the synthesis and characterization are given in [ 176 , 180 ] and will not be repeated here.…”

“…There are two different strategies for obtaining such peptide-functionalized silica materials, namely an activation of the silica by virtue of a linker group, followed by a grafting of the previously synthesized peptide as shown, e.g., in [ 47 , 112 ] or the direct synthesis of the desired peptide inside the pores employing a modification of the standard SPPS protocol [ 176 , 177 , 194 ].…”

“…Molecules 2020, 25, x FOR PEER REVIEW 5 of 31 example) and to employ special drying protocols for the preparation of "water-free" silica samples (for details see Brodrecht et al [183]). Since naturally-occurring porous hybrid materials like the skeleton of diatoms are based on modified silica materials consisting of silica and sillafins (polyamines) [184][185][186][187], the functionalization of mesoporous silica with peptides and peptoides [44,47,113,[175][176][177][178][188][189][190][191][192][193][194] creates controllable well-defined model systems for the in-vitro study of, e.g., biomineralization.…”

Cooperative formation of porous silica and peptides on the prebiotic Earth

“…There have also been studies of the sorption and binding of peptides on bulk and nanophase mesoporous silica. Brodrecht et al (39,40) investigated mesoporous silica modified through inpore grafting of small peptides. The structure and surface functionalization were investigated by 2D solid state NMR combined with dynamic nuclear polarization and covalent binding was confirmed.…”