Formulation, Characterization, and In Vitro Cytotoxic Evaluation of Etoposide-Loaded Nanobubbles for Enhanced Cancer Chemotherapy

Abstract

This study aimed to develop, characterize, and evaluate the in vitro cytotoxic potential of Etoposide-loaded nanobubbles for enhanced cancer therapy. Nanobubbles were formulated using a thin-film hydration technique followed by probe sonication, employing phosphatidylcholine, cholesterol, and PEG-4000 as the lipid matrix. Five formulations (F1–F5) were developed with varying lipid concentrations and characterized for particle size, zeta potential, polydispersity index (PDI), entrapment efficiency, and drug loading. The optimized formulation (F5) exhibited a particle size of 125.5 ± 2.1 nm, zeta potential of –30.6 ± 0.7 mV, and entrapment efficiency of 91.4 ± 1.1%. In vitro release studies revealed a sustained drug release pattern over 48 hours, with F5 achieving 99.4 ± 0.6% release. Kinetic modelling confirmed a first-order release mechanism with non-Fickian diffusion behaviour. Cytotoxicity studies using the MTT assay were performed on MCF-7 (breast), A549 (lung), and HeLa (cervical) cancer cell lines. The Etoposide-loaded nanobubbles demonstrated significantly enhanced cytotoxicity compared to free drug, with lower IC₅₀ values in all tested cell lines, while blank nanobubbles showed negligible toxicity. These findings support the potential of nanobubble-based systems for targeted and controlled delivery of chemotherapeutic agents, offering improved therapeutic efficacy and reduced systemic toxicity