Hierarchical Self-Assembly of Peptide Nanofibers: From Amino Acids to Therapeutic Hydrogels

Self- assembling peptide nanofibers have become a groundbreaking class of biomaterials for drug delivery, offering exceptional control over structural organisation from the molecular level to larger scales. This review explores the core principles, design strategies, and therapeutic uses of peptide nanofiber- based systems, emphasising their transformative role in modern pharmaceuticals. The hierarchical self- assembly begins with carefully designed amphiphilic peptide sequences, usually consisting of 8-20 amino acids with alternating hydrophobic and hydrophilic residues, which naturally form β- sheet structures through hydrogen bonding, hydrophobic forces, and electrostatic interactions. These molecular structures grow into nanofibers with high aspect ratios and diameters of 5-50 nanometers, which then entangle into three- dimensional hydrogels containing over 99% water. Such materials are highly biocompatible due to their amino acid makeup, have adjustable mechanical properties suited for different tissues, and are fully biodegradable into non- toxic metabolites. We cover peptide sequence design principles, including key systems like EAK 16 and RADA 16, along with new computational and machine learning methods for optimising sequences. Strategies for chemical modification, hybrid system creation, and functionalization- such as multi- drug loading, stimuli- responsive release, and cellular targeting- are thoroughly discussed. Drug loading mechanisms, including physical encapsulation, chemical conjugation, surface adsorption, and guest- host interactions, are analysed along with release kinetics and pharmacokinetic benefits compared to traditional carriers. We also review characterisation methods, biocompatibility testing, and regulatory issues to guide translational development. Clinical applications across cancer, neurological disorders, infections, regenerative medicine, and protein delivery are showcased with case studies demonstrating therapeutic success. Finally, we identify future research priorities and evaluate the practical potential of these remarkable biomaterials to improve human health.