Peptide self-assemblies for drug delivery

Peptide amphiphiles (PAs), are novel engineered biomaterials able to self-assemble into supramolecular systems with applications in delivery across challenging biological barriers and intracellularly particularly in the field of brain diseases, regenerative medicine and cancer. PAs are amino-acid block co-polymers, with a peptide backbone composed usually of 8-30 amino acids, a hydrophilic block formed by polar amino acids and an apolar block which usually entails either apolar or aromatic amino acids and alkyl, acyl or aryl lipidic tails and in some cases a spacer or a conjugated targeting moiety. Alteration in the balance between the hydrophilic and hydrophobic blocks result in a range of supramolecular structures that are usually stabilised by hydrophobic, electrostatic, β-sheet hydrogen bonds and π-π stacking interactions. In an aqueous environment, the final size, shape and interfacial curvature of the PA is a result from the complex interplay of all interactions. Lanreotide is the first PA to be licensed for the treatment of acromegaly and neuroendocrine tumours as a hydrogel administered subcutaneously, while a number of other PAs are undergoing preclinical development. This review discusses PAs architecture fundamentals that govern their self-assembly into supramolecular systems for applications in drug delivery.