Gold nanoparticles capped with inclusion complex for the delivery of Chrysin in triple-negative breast cancer

Chrysin (CHR), a naturally occurring flavonoid with promising anticancer potential, suffers from poor water solubility, limiting its therapeutic applications. To address this, β-Cyclodextrin (β-CD) inclusion complexes (ICs) of CHR were synthesized via the freeze-drying method at varying molar ratios (1:1, 1:2, 1:3, 1:4), with the 1:4 ratio exhibiting the highest entrapment efficiency (95.23%) and selected for further study. These ICs were then functionalized onto gold nanoparticles (AuNPs) to develop CHR-β-CD-AuNPs, enhancing drug delivery and stability. Characterization by UV-Vis, FTIR, NMR, NTA, and TEM confirmed successful encapsulation, hydrogen bonding, and spherical morphology with an average particle size of ~ 43 nm. Molecular docking supported strong interactions between CHR and β-CD. In vitro studies against human triple-negative breast cancer (MDA-MB-231) cells demonstrated that CHR-β-CD-AuNPs exhibited potent cytotoxicity with an IC₅₀ of 22.17 ± 1.24 mg/L, significantly lower than CHR/β-CD ICs (IC₅₀: 22.84 ± 1.00 mg/L) and free CHR (IC₅₀ > 100 mg/L, p < 0.001). Hoechst and phalloidin staining revealed clear apoptotic features such as nuclear fragmentation and cytoskeletal disruption. Gene expression analysis showed upregulation of Bax and Caspase-3 and downregulation of Bcl-2, confirming apoptosis induction. Furthermore, scratch wound assays demonstrated significant inhibition of cancer cell migration, with wound closure reduced to 8.38 ± 0.74% (IC) and 15.27 ± 1.05% (IC-AuNPs) compared to 74.41 ± 1.22% in untreated controls (p < 0.001). These findings establish that β-CD-based CHR-AuNP nanocarriers substantially improve the solubility, stability, and therapeutic efficacy of CHR, offering a promising nanoformulations strategy for enhanced targeted breast cancer therapy.