Self-assembly of ionic-complementary peptides: a physicochemical viewpoint

A major focus in the current development in nanotechnology and biotechnology is to find suitable molecular materials that are amenable to engineering design. Self-assembling, ionic-complementary peptides have recently emerged as one of the most promising biomolecular materials. We provide a brief review of recent research on these newly discovered peptides from a physicochemical point of view. This new class of peptides has a unique molecular structure of alternating positive and negative charge distributions, leading to ionic-complementarity. In addition to hydrogen bonding and hydrophobic interaction, the ionic-complementarity contributes to peptide self-assembly. These peptides assume β-sheet secondary structure predominantly, and can further self-assemble into fibrils, membranes, and even hydrogels with an increase in peptide concentration or other physicochemical parameters. The self-assembly process is highly dependent on the peptide sequence, concentration, pH, presence of salts, and time (or kinetics). By varying these experimentally controllable factors, nanoscopic and/or macroscopic structures with great stability and functionality can be constructed. These nano/microstructures have various biomedical applications, including tissue engineering, drug/gene delivery and biological surface patterning. It is anticipated that molecular engineering of these ionic-complementary peptides will contribute in a significant way to the development of novel nanobiomaterials, and play an important role in the advance of rapidly emerging bionanotechnology fields.