Bevacizumab-targeted porous casein-coated cobalt ferrite nanoparticles: A potent theranostic agent for sunitinib delivery, VEGF trapping, and MRI

Synthesis of casein-coated cobalt ferrite nanoparticles (CACoFe NPs) using a simple one-pot hydrothermal method and their potential application as a cancer theranostic agent is reported. The colloidal and monodispersed CACoFe NPs represented an average hydrodynamic size of 245.4 nm, a zeta potential of −54.9 mV and a polydispersity index (PDI) of 0.282. These semi-spherical and crystalline NPs displayed a saturation magnetization of 46.54 emu g⁻¹ and a porous structure with a specific surface area of 118.8 m² g⁻¹ and total pore volume of 0.3 cm³ g⁻¹. CACoFe NPs served as a nanocarrier for targeted delivery of sunitinib, achieving a high loading capacity of 162 µg mg⁻¹ and cumulative release of 56.44 % over 48 h. MTT assay showed only 12.3 % mortality of MDA-MB-231 cancer cells after 24 h exposure with 200 μg mL⁻¹ CACoFe NPs while 59.9 % and 68.5 % cell death were obtained at the same condition using the bevacizumab functionalized CACoFe NPs (B-CACoFe NPs) and the sunitinib loaded B-CACoFe NPs (S-B-CACoFe NPs), respectively. Apoptosis was confirmed as the primary anticancer mechanism of S-B-CACoFe NPs through real-time PCR, flow cytometry and ELISA studies. The chorioallantoic membrane (CAM) assay demonstrated significant anti-angiogenic effect of S-B-CACoFe NPs. Furthermore, the ability of B-CACoFe NPs to entrap vascular endothelial growth factor (VEGF) was validated in situ and in vivo with entrapment efficiency of 76.5 % and 68.3 %, respectively. Additionally, CACoFe NPs exhibited a high R₂ relaxivity value of 81.6 mM⁻¹ S⁻¹ and were successfully used as a contrast agent for magnetic resonance imaging (MRI) of tumor-bearing mice.