The accumulation of bacteria on surfaces is currently one of the greatest concerns f or the supply of proper health, water and energy. Here, we describe the mechanism by which a single peptide forms two pH-dependent supramolecular particles that resist bacterial contamination. By using NMR and molecular dynamics ( MD), we determined the structures of the peptide monomers and showed the forces directing the self-assembly of each structure under different conditions. These peptide assemblies change the characteristics of bare gla s and confer it with the ability to prevent biofilm formation. Furthermore, they can adsorb and re ease active compounds as demonstrated with an anticancer drug, antibiotic and enzyme. This synergism and the detailed understanding of the proces ses are necessary for developing new sterile surfaces for health-care systems, water puri ication devices, food packaging or any environment that suffers from biocontamination.