Exploration of cellular uptake and endocytosis mechanisms for doxorubicin-loaded poly (amino acid) nanocarriers

Abstract

This study revolves around the synthesis of poly (amino acid)-based polymers, specifically designed as block copolymers incorporating poly (glutamic acid) and poly (ethylene glycol), with varying glutamic acid moieties. Extensive characterization of these block copolymers was carried out using Fourier Transform Infrared and proton nuclear magnetic resonance (¹H NMR) spectroscopy. The integration of the potent anti-cancer agent, doxorubicin, into these constructs was successfully achieved. The determination of nanoparticle sizes was accomplished through dynamic laser light scattering; while, zeta potential measurements provided insights into surface charges. Following the drug loading into nanomicelles, the release profiles were investigated under conditions simulating the tumor-specific acidic pH and physiological blood pH (7.4). In vitro cytotoxicity evaluations were performed, revealing dose and time-dependent reactions for both free and loaded doxorubicin against the MCF-7 breast cancer cell line. Additionally, the mechanisms of cellular uptake were explored using confocal laser scanning microscopy and flow cytometry. The findings unveiled that the cellular uptake of free doxorubicin predominantly follows a diffusion process; while, the drug loaded within nanoparticles is internalized via endocytosis. The nanoparticles were skillfully engineered to possess optimal size, shape, and surface charge, thereby showcasing their potential as proficient vehicles for targeted drug delivery. In summary, this study not only demonstrates the successful synthesis and meticulous characterization of poly (amino acid)-based nanocarriers but also underscores their biocompatibility, favorable attributes, and promising capabilities as effective platforms for precise and targeted drug delivery.