Self-assembly and cellular distribution of a series of transformable peptides

Transformable peptides (TPs) are biomedical materials with unique structures and diverse functionalities that have drawn great interest in materials science and nanomedicine. Here, we design a series of TPs with five self-assembling sequences conjugated with the hydrophobic unit bis(pyrene) and the targeting sequence RGD, and study the transformable features induced by ligand (RGD)-receptor (integrin or Ca²⁺) interactions. TPs are able to self-assemble into nanoparticles or nanosheets and then transform into nano-aggregates or nanofibers induced by RGD-Ca²⁺ interactions in solution. When TPs are incubated with breast cancer cells expressing integrin receptors on the cell membrane, it is found that they display different cell distributions, including adhesion on the cell membrane, location in the lysosome, or escape from the lysosome to cytoplasm. This study reveals that the self-assembling sequence affects the dynamic self-assembly nanostructures of TPs and the resultant biodistribution in cells.