The present embodiments relate to antibody binding nanofibrils obtainable by co-fibrillation of carrier proteins and carrier-Z fusion proteins at a molar ratio selected within an interval of from 1:0.20 to :0.90. The antibody binding nanofibrils have extremely high antibody binding capacity and can thereby be used in various applications, such as antibody purification, and detection of biomarkers in point of care or laboratory diagnosis applications.