However, additional non-covalent interactions can be controlled between these peptides to further modulate their self-assembly and tune the properties of the composite material. Here we set out to investigate the roles of long-range electrostatic repulsion and short-range attractive interactions through additional hydrogen bonding interactions in the amino acid side groups . The overall charge of the peptide sequence was altered from neutral to extremes (+4 and -6) through the removal or addition of polar amino acids (glutamic acid, ornithine and arginine), while amino acid side chain hydrogen bonding was modulated at the four peripheral amino acid positions through the uncharged polar amino acids serine and glutamine .