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Enzyme-Induced Transformable Peptide Nanocarriers with Enhanced Drug Permeability and Retention to Improve Tumor Nanotherapy Efficacy.

Temporal persistence is as important for nanocarriers as spatial accuracy. However, because of the insufficient aggreagtion and short retention time of chemotherapy drugs in tumors, their clinical application is greatly limited. A drug delivery approach dependent on the sensitivity to an enzyme present in the microenvironment of the tumor is designed to exhibit different sizes in different sites, achieving enhanced drug permeability and retention to improve tumor nanotherapy efficacy. In this work, we report a small-molecule peptide drug delivery system containing both tumor-targeting groups and enzyme response sites. This system enables the targeted delivery of peptide nanocarriers to tumor cells and a unique response to alkaline phosphatase (ALP) in the tumor microenvironment to activate morphological transformation and drug release. The amphiphilic peptide AYR self-aggregated into a spherical nanoparticle structure after encapsulating the lipid-soluble model drug doxorubicin (DOX) and rapidly converted to nanofibers via the induction of ALP. This morphological transformation toward a high aspect ratio allowed rapid, as well as effective drug release to tumor location while enhancing specific toxicity to tumor cells. Interestingly, this "transformer"-like drug delivery strategy can enhance local drug accumulation and effectively inhibit drug efflux. In vitro along with in vivo experiments further proved that the permeability and retention of antitumor drugs in tumor cells and tissues were significantly enhanced to reduce toxic side effects, and the therapeutic effect was remarkably improved compared with that of nondeformable drug-loaded peptide nanocarriers. The developed AYR nanoparticles with the ability to undergo morphological transformation in situ can improve local drug aggregation and retention time at the tumor site. Our findings provide a new and simple method for nanocarrier morphology transformation in novel cancer treatments.