Abstract
The fabrication of two-dimensional (2D) biomineral nanosheets is of high interest owing to their promise for applications in electronics, filtration, catalysis, and chemical sensing. Using a facile approach inspired by biomineralization in nature, we fabricate laterally macroscopic calcium oxalate nanosheets using β-folded peptides. The template peptides are composed of repetitive glutamic acid and leucine amino acids, self-organized at the air–water interface. Surface-specific sum frequency generation spectroscopy and molecular dynamics simulations reveal that the formation of oxalate nanosheets relies on the peptide–Ca2+ ion interaction at the interface, which not only restructures the peptides but also templates Ca2+ ions into a calcium oxalate dihydrate lattice. Combined, this enables the formation of a critical structural intermediate in the assembly pathway toward the oxalate sheet formation. These insights into peptide–ion interfacial interaction are important for designing novel inorganic 2D materials.
Highlights
The design and synthesis of 2D nanomaterials have opened up a new field of ultrathin, functional materials with atomic precision.[1]
The template peptides are composed of repetitive glutamic acid and leucine amino acids, selforganized at the air−water interface
Surface-specific sum frequency generation spectroscopy and molecular dynamics simulations reveal that the formation of oxalate nanosheets relies on the peptide−Ca2+ ion interaction at the interface, which restructures the peptides and templates Ca2+ ions into a calcium oxalate dihydrate lattice
Summary
To investigate the potential of CaC2O4 biominerals as a 2D material, we report here the synthesis of CaC2O4 nanosheets at the air−water interface using biomimetic peptides (Figure 1A). This secondary structure is expected based on folding of the analogue positively charged leucine−lysine (LK) peptides at interfaces.[27]. Dynamics simulation studies indicate that the nanosheet formation is enabled by the key interplay between peptides and Ca2+ ions: binding of the Ca2+ ions refines the peptide’s structural motif, which in turn templates the Ca2+ ions to nucleate the CaC2O4 nanosheet by matching the COD lattice. The study shows that the inclusion of ion interactions in the design of functional peptides will be important for the design and fabrication of 2D inorganic biomimetic mineral nanosheets This strategy could potentially be used to design mineral sheets using related templating molecules such as peptoids and block copolymers.
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