LL-37 (human) Trifluoroacetate Salt (LL-37) is a naturally-occuring antimicrobial peptide that is part of the innate host immune system. It is associated with the epidermis and protects the host from bacterial infection. LL-37 has also demonstrated a range of other bioactivity including anti-influenza, immunomodulatory, and cell death activity in certain cell types. Unlike other antimicrobial peptides, LL-37 can aggregate to protect from proteolytic degredation. This protein fibril can act as a scaffold for functional and durable biomaterials for a wide range of medical and technological applications.