Peptide Mimic of the Marine Sponge Protein Silicatein Fabricates Ultrathin Nanosheets of Silicon Dioxide and Titanium Dioxide

Abstract

Two-dimensional (2D) materials have attracted attention for potential applications in light harvesting, catalysis, and molecular electronics. Mineral proteins involved in hard tissue biogenesis can produce 2D structures with high fidelity by using sustainable production routes. This study shows that a peptide mimic based on the catalytic triad of the marine sponge protein silicatein catalyzes the formation of nanometer thin and stable sheets of silicon dioxide and titanium dioxide.

Conformation and Orientation of Antimicrobial Peptides MSI-594 and MSI-594A in a Lipid Membrane

“…SFG is a second-order nonlinear optical spectroscopic technique that has proven powerful in investigating molecular structures of peptides and proteins at interfaces. − SFG is a submonolayer surface-sensitive optical technique and is capable of investigating the interfacial conformation and orientation of peptides and proteins associated with a model cell membrane surface at a low peptide/protein solution concentration. − , The details regarding SFG theories and measurements have been published previously − ,− …”

“…SFG spectra from interfacial peptides in different polarization combinations including ssp (s-polarized output SFG signal, s-polarized input visible beam, and p-polarized input IR beam) and ppp were collected using the near total internal reflection geometry (Figure c). The detected SFG intensity ( I SFG ) can be expressed as follows: − ,− where χ eff (2) is the effective second-order susceptibility, and χ NR (2) is the non-resonant contribution. A q , ω q , and Γ q are the SFG signal amplitude, the vibrational frequency (peak center), and the damping coefficient (peak width) of the vibrational mode q, respectively.…”

“…On the other hand, sum frequency generation (SFG) vibrational spectroscopy, a second-order nonlinear optical spectroscopy, can be effectively used to overcome some of these limitations. Previous research demonstrated the use of SFG to study the molecular structures of biological molecules such as peptides and proteins at interfaces in situ in real time. − SFG was used to measure peptide’s/protein’s membrane orientation and study antimicrobial peptide–cell membrane interactions in a large range of peptide solution concentrations, − which could not be done by many commonly used techniques. Our research also demonstrated that ATR-FTIR could serve as a supplemental tool to SFG to provide more detailed structural information on interfacial peptides and proteins. , SFG and ATR-FTIR can probe peptide–lipid bilayer interactions at a very low peptide concentration in situ in real time.…”