Polysaccharide‐Coated <scp>ETCA</scp> Nanoparticles Containing the Methoxyl Substituted Indole‐Thiazole Derivative and Their Antiproliferative Activity in Breast Cancer Cells

ABSTRACT Indole and thiazole derivatives have garnered significant attention due to their potent antitumor activities. Encapsulation of such derivatives into polymeric nanoparticles offers several advantages, including improved molecular stability and targeted delivery to tumor sites, thereby enhancing their antineoplastic potential. This study aimed to encapsulate a novel methoxyl‐substituted indole‐thiazole derivative (CS08) into polymeric nanoparticles and evaluate its antiproliferative activity against metastatic breast cancer cells (MDA‐MB‐231). Nanoparticles were prepared using the anionic emulsion polymerization (AEP) technique and coated with either dextran or fucoidan as biocompatible polysaccharides. The resulting nanoparticles were characterized for their physicochemical properties, including particle size, zeta potential, morphology via scanning electron microscopy (SEM), and structural composition using infrared (IR) spectroscopy. Dextran‐coated nanoparticles exhibited an average diameter of 232.7 ± 0.55 nm and a zeta potential of +15.6 ± 0.45 mV, whereas fucoidan‐coated nanoparticles had a larger size of 389.2 ± 19.97 nm and a more negative zeta potential of −63.9 ± 1.13 mV. Importantly, both nanoparticle formulations were noncytotoxic to macrophage cells. Moreover, CS08‐loaded nanoparticles demonstrated enhanced antiproliferative activity against MDA‐MB‐231 cells, surpassing the efficacy of doxorubicin in vitro. These findings highlight the potential of CS08‐loaded polymeric nanoparticles as promising candidates for metastatic breast cancer therapy.