# Surface Avidity of Anionic Polypeptide Coatings on Layer‐by‐Layer Nanoparticles Target Cancer‐Associated Amino Acid Transporters

## TL;DR

Researchers found that anionic polypeptide coatings on nanoparticles target cancer cells by binding to amino acid transporters, improving drug delivery.

## Contribution

The study reveals how anionic polypeptides selectively target cancer-associated amino acid transporters through electrostatic interactions.

## Key findings

- PLE-coated nanoparticles bind to SLC1A5 and cluster it on the cell membrane.
- PLD-coated nanoparticles bind SLC1A5 and also interact with SLC1A3 for faster internalization.
- Transporter expression correlates with nanoparticle association across cancer cell lines.

## Abstract

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 (NP) 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.

Electrostatically layered nanoparticles (NPs) coated with anionic polypeptides selectively target cancer cells by engaging amino acid transporters. Poly(L‐glutamate) (PLE) coatings cluster the glutamine transporter SLC1A5, prolonging NP surface retention, while poly(L‐aspartate) (PLD) coatings also bind SLC1A3, potentially promoting faster internalization. This mechanistic framework reveals how multivalent polypeptide presentation enables receptor‐specific NP delivery across diverse tumor types.