Construction of diverse PLL-based drug delivery systems. (A) Antibacterial polypeptides-grafted chitosan-based nanocapsules as “armed” drug carriers. Reproduced with permission from Ref. [153], copyright 2013, American Chemical Society. (B) Surface-crosslinked polymeric micelles from amphiphilic star-block copolymers for indomethacin (IND) encapsulation. Reproduced with permission from Ref. [157], copyright 2017, Elsevier. (C) Injectable polypeptide-based fibrous hydrogels for the delivery of chlorin e6. Reproduced with permission from Ref. [158], copyright 2018, American Chemical Society.