Enhanced anticancer efficacy of α-lipoic acid-loaded TPGS micelles: Synthesis, characterization, and evaluation in a 4T1 breast cancer model.

Abstract

Introduction: α-Lipoic acid (ALA) is a potent antioxidant with anticancer properties, but its clinical application is limited by poor water solubility and low bioavailability. Current nanocarrier systems for ALA delivery suffer from low encapsulation efficiency, rapid drug release kinetics, and biocompatibility concerns that restrict their therapeutic potential. This study aimed to develop and evaluate ALA-loaded D-alpha-tocopheryl polyethylene glycol succinate (TPGS) micelles as an innovative nanomedicine platform to overcome existing limitations and enhance anticancer efficacy.

Methods: ALA was loaded into TPGS micelles via modified solvent evaporation method and comprehensively characterized by TEM, DLS, and FTIR examination. Drug loading and encapsulation efficiency were quantitatively determined. In vitro drug release kinetics, cellular uptake and cytotoxicity were assessed in 4T1 breast cancer cells. Gene expression analysis was performed, and in vivo antitumor efficacy was evaluated in 4T1 murine xenograft model with histopathological examination.

Results: The formulation achieved superior encapsulation efficiency of 70%, with DLS analysis revealing micelles having mean diameter of 30-40 nm (polydispersity index: 0.234) and zeta potential of -1.9 mV. TEM confirmed spherical morphology. FTIR validated structural integrity with characteristic peaks. In vitro release demonstrated burst release of 52.4±2.5% (6 hours) followed by sustained release reaching 85.9±2.5% (48 hours). Flow cytometry showed 13.75-fold increased cellular uptake (15.4% vs 1.12% FL4-H+cells). MTT assay revealed dose-dependent cytotoxicity. qRT-PCR demonstrated significant upregulation of apoptotic markers: Caspase-8 (2.071-fold, 95% CI: 1.308-3.299, P<0.001) and Caspase-9 (2.86-fold, 95% CI: 1.102-7.785, P<0.001). In vivo studies in 4T1 murine xenograft model showed 10.39% reduction in tumor growth rate (8.54±3.83 mm³/day vs 9.53±1.03 mm³/day in controls) with histopathological evidence of decreased mitotic activity (28 vs 36 mitoses/10 HPF) and increased apoptosis (11 vs 5 apoptotic figures/10 HPF). All treatment groups achieved 100% survival throughout the 17-day study period with maintained body weights, confirming excellent biocompatibility.

Conclusion: ALA-loaded TPGS micelles demonstrate enhanced anticancer efficacy through improved drug delivery, controlled release kinetics, and effective modulation of apoptotic pathways, supporting their potential for clinical translation in cancer therapy.