Amphiphilic Peptidic Molecular Brushes: Synthesis And Characterization

Enhanced chiralities and ordered structures can be better realized byamphiphilic peptides when compared to conventional counterparts, which is veryimportant in designing novel functional peptidic materials. In order to simulate theseadvantages from amphiphilic peptides, molecular brushes constituted with thesepeptides as side chains should provide an effective notion to possibly enhance thesecondary structures within the constrained conditions, at the same time, to pave anew route for fabricating functional peptidic materials.Two types of molecular brushes which carry amphiphilic peptides terminatedwith free amino or TEG groups, respectively, are designed and synthesized in presentwork. The backbones of the molecular brushes are based on polymethacrylate, whilethe side octa-peptidic chains are constituted with alternative Glu and Phe moieties.1H NMR and CD measurements were carried out to characterize their secondarystructures. Two kinetically stable conformers from the amphiphilic peptidicmonomer terminated with Boc-protected amine group can be separated by columnchromatography, and were verified by1H NMR spectroscopy. Comparing to thedeprotected macromonomers, the deprotected molecular brushes adopt enhancedsecondary structures in aqueous solutions. In other side, protected molecular brushesshow much ordered structures than these deprotected counterparts. Furthermore,deprotected molecular brushes show the tendency to adopt β folding, while theytend to switch into random coil at strong basic conditions due to the chargerepulsion.Generally specking, molecular brushes constituted with amphiphilic peptidic side chains provide a convenient route to control the secondary structures of peptidesby changing terminal groups, solvent polarities, and solution pH values.