Size‐Transformable Bicomponent Peptide Nanoparticles for Deep Tumor Penetration and Photo‐Chemo Combined Antitumor Therapy

The suitable size of multifunctional nanomedicines strongly influences their physicochemical properties and actions in biological systems, for example, prolonged blood circulation time, efficient tumor accumulation, and deep tumor penetration. However, it is still a great challenge to construct size‐transformable nanoparticles (NPs) for both efficient accumulation and penetration throughout tumor tissue. Herein, a size‐transformed multifunctional NP is developed through a simple bicomponent assembling strategy for enhanced tumor penetration and efficient photo‐chemo combined antitumor therapy, due to the acidic tumor microenvironment and near infrared‐laser irradiation induced size‐shrink. This multifunctional bicomponent NP (PP NP) driven by electrostatic interaction is composed of negatively charged peptide amphiphile (PA1) and positively charged peptide prodrug (PA2). PP NPs (≈170 nm) have been proven to improve blood circulation time and stability in biological environments. Interestingly, PP NPs can reassemble small NPs (