Nanoemulsions as carriers for malignant brain tumors treatment: a scoping review on drugs, natural compounds, and siRNA delivery

Malignant brain tumors are a highly complex and heterogeneous group of neoplasms, with glioblastoma being the most aggressive and treatment-resistant form. Standard therapies remain insufficient, largely due to poor drug penetration across the blood-brain barrier and tumor heterogeneity. Lipid-based nanoemulsions have emerged as promising nanocarriers capable of enhancing drug solubility, protecting unstable compounds, and facilitating targeted delivery across the blood-brain barrier. This scoping review analyzed 19 studies focused on lipid-based nanoemulsions for brain tumor therapy, particularly those incorporating synthetic drugs, natural compounds, and nucleic acids. Key formulation strategies, preparation methods, and physicochemical characteristics were outlined. The majority of studies demonstrated in vitro cytotoxicity against rat C6 and human U87MG glioma cell lines. Particularly, nanoemulsions loaded with temozolomide, and siRNA targeting CD73 reduced tumor growth in glioma-bearing rats, especially via nasal administration. Natural products such as kaempferol and honokiol also showed antiglioma effects in vitro when delivered through nanoemulsions. These findings highlight the potential of nanoemulsions in neuro-oncology, particularly for noninvasive nose-to-brain delivery and gene silencing therapies. Further research is needed to standardize formulations and validate their efficacy and safety in clinical settings.