Biotin-Directed Solid Lipid Nanoparticles for Targeted Delivery of Methotrexate in Biotin Receptor-Overexpressing Tumors

Biotin (BTN) receptors, overexpressed in numerous cancer cells, have emerged as promising targets for the development of targeted cancer therapies. In the context of cancer, the overexpression of BTN receptors is thought to be linked to the increased demand for BTN-dependent enzymes and pathways necessary for sustaining the rapid proliferation of cancer cells. The current research has been directed toward developing surface-modified (with BTN) solid lipid nanoparticles (SLNs) that are loaded with methotrexate and can transport the drug to particular cancerous regions. In order to produce SLNs, a BTN-based lipid called N-biotinoyl-n-hexadecylamine (C16–BTN) was synthesized and employed as a colipid combined with stearic acid and cetyl alcohol targeting BTN receptors. Various techniques, such as dynamic light scattering (DLS), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), ultraviolet–visible (UV–vis) spectroscopy, and high-resolution transmission electron micrographs (HRTEM), were used to characterize each of the SLN formulations. Using the human breast cancer MCF7 and human lung cancer A549 cell lines, flow cytometry, and the MTT assay were used to investigate the in vitro cytotoxicity and apoptosis-mediated cell death. In-vitro cell cytotoxicity study in MCF7 and A549 cell lines showed the surface-modified, methotrexate-loaded SLNs are more effective in cell killing and induction of apoptotic death in both the cell lines than free methotrexate in MTT and flow cytometry studies. The surface-modified SLNs were radiolabeled with 99mTc with %RCP greater than 95%. Biodistribution studies with 99mTc-labeled nanoparticles in A549 (lung) and B16F10 (melanoma) tumor models revealed selective accumulation in BTN receptor-overexpressing A549 tumors, with minimal uptake in B16F10. SPECT/CT imaging confirmed strong radiotracer localization in the A549 tumor. These findings underscore the potential of BTN-functionalized SLNs as effective nanocarriers for targeted chemotherapeutic delivery to BTN receptor-overexpressing cancer tumors.