Cyclic dipeptide nanoribbons formed by dye-mediated hydrophobic self-assembly for cancer chemotherapy

Cyclic dipeptides (CDPs), the smallest naturally occurring cyclic peptides, have attracted tremendous attention due to their exceptional biological and pharmacological activities such as antitumor, antimicrobial, and immune regulation. However, controlled fabrication of CDPs nanostructures to address the problem of poor aqueous solubility and low bioavailability existing in therapeutic application is still in challenging, due to their remarkable structural rigidity and superior hydrogen-bonding-forming capability. Herein, a simple but robust and universal strategy for the construction of CDP nanoribbons based on the amphiphilic dye-mediated hydrophobic self-assembly is presented. The amphiphilic dyes not only provide the robust hydrophobic interaction for the formation of CDP nanoribbons but also offer enough electrostatic repulsion forces to stabilize the formed assemblies. Moreover, the introduction of functional dyes endows the assembled CDP nanoribbons multiple benign therapeutic features, including adjustable shape and size, improved bioavailability, as well as preferable cellular uptake and biodistribution, thereby enhanced chemotherapy efficacy in vitro and in vivo. The strategy developed based on the dye-mediated self-assembly provides a promising way to rationally design water-insoluble bioactive CDPs for therapeutic applications.