Surface avidity of anionic polypeptide coatings target nanoparticles to cancer-associated amino acid transporters

Tumor-targeted drug delivery enhances therapeutic efficacy while minimizing toxicity. Layer-by-layer nanoparticles (LbL-NPs) coated with anionic polypeptides selectively bind to cancer cells, though the mechanisms have been unclear. Here, we integrated in silico and in vitro approaches--including gene expression analysis, receptor inhibition, and AI-based protein modeling--to show that poly(L-glutamate) (PLE)-coated LbL-NPs bind with high avidity to SLC1A5, a glutamine transporter overexpressed in cancer. We also discovered that PLE clusters SLC1A5 on the cell membrane, promoting prolonged cell surface retention. Poly(L-aspartate) (PLD)-coated NPs similarly bind SLC1A5 but also interact with faster internalizing transporters of anionic amino acids. Correlation analyses across cancer cell lines confirmed a strong link between transporter expression and nanoparticle association. These findings demonstrate that dense glutamate or aspartate presentation through electrostatically adsorbed polypeptides enables selective targeting of overexpressed transporters, providing a mechanistic framework for receptor-targeted delivery that leverages metabolic characteristics of a range of solid tumor types.