Polypeptide-based nanocarriers from aqueous ROPISA: Shape-dependent performance in colorectal and breast cancer models

Polypeptide-based nanocarriers are key to the field of drug delivery, however the influence of morphology on their performance remains underexplored. In this study, we present a novel method for the synthesis of fluorescent worm-like nanoparticles, namely the one-step aqueous ring-opening polymerization-induced self-assembly (ROPISA) of γ-benzyl-l-glutamate N-carboxyanhydride (BLG-NCA). To assess the comparative efficacy of this formulation, we prepared spherical analogues via solvent displacement, enabling direct evaluation of their cellular uptake and in vivo biodistribution. Using CT26 (colorectal carcinoma) and 4T1 (triple-negative breast cancer) models, which have been shown to exhibit different tumor vascularity and permeability, we first examined internalization in 2D cultures and 3D spheroids. The results demonstrated that both morphologies efficiently internalized, with faster uptake observed in CT26 cells but higher accumulation seen in 4T1 cells. In 3D spheroids, both nanoparticles penetrated tumor-like structures, although diffusion was slower in 4T1 spheroids but resulted in higher final accumulation. In vivo, prolonged circulation and significant tumor accumulation were then monitored in both models, especially in 4T1 tumors. These findings highlight ROPISA of NCA as a robust platform for polypeptide nanocarrier synthesis, thereby paving the way for drug-loaded nanoparticles via covalent grafting or in situ encapsulation and thus advancing nanomedicine for precision drug delivery.