Programming co-assembled peptide nanofiber morphology via anionic amino acid type: Insights from molecular dynamics simulations.

Co-assembling peptides can be crafted into supramolecular biomaterials for use in biotechnological applications, such as cell culture scaffolds, drug delivery, biosensors, and tissue engineering. Peptide co-assembly refers to the spontaneous organization of two different peptides into a supramolecular architecture. Here we use molecular dynamics simulations to quantify the effect of anionic amino acid type on co-assembly dynamics and nanofiber structure in binary CATCH(+/-) peptide systems. CATCH peptide sequences follow a general pattern: CQCFCFCFCQC, where all C's are either a positively charged or a negatively charged amino acid. Specifically, we investigate the effect of substituting aspartic acid residues for the glutamic acid residues in the established CATCH(6E-) molecule, while keeping CATCH(6K+) unchanged. Our results show that structures consisting of CATCH(6K+) and CATCH(6D-) form flatter ß-sheets, have stronger interactions between charged residues on opposing ß-sheet faces, and have slower co-assembly kinetics than structures consisting of CATCH(6K+) and CATCH(6E-). Knowledge of the effect of sidechain type on assembly dynamics and fibrillar structure can help guide the development of advanced biomaterials and grant insight into sequence-to-structure relationships.

New Solid-Base Cu-MgO for CO2 Capture at 473 K and Removal of Nitrosamine.

To fabricate a new solid base with high efficiency in the adsorption of CO2 at 473 K and catalytic activity in the degradation of nitrosamines, magnesium oxalate and copper nitrate are mixed with the assistance of microwave irradiation followed by calcination to immobilize CuO among MgO particles. The binary solid base CuO-MgO is thus moderately reduced to form the Cu-inserted MgO composite with highly exposed strong basic sites, and it can capture 34.6 mg g-1 of CO2 in the harsh instantaneous adsorption at 473 K and keep a high strong basicity while trapping the CO2 mixed with SO2 and NO. Besides this, the new solid base exhibits high activity in the removal of volatile nitrosamine N-nitrosopyrrolidine (NPYR), for the first time expanding the application of solid bases to environmental catalysis.