Cerium-based nanoparticles for neurodegeneration: emerging redox therapeutics beyond pharmaceuticals.

Delivering therapeutic agents across the blood-brain barrier (BBB) remains a formidable hurdle in the treatment of neurodegenerative diseases, which are primarily driven by mitochondrial dysfunction, oxidative stress, and neuroinflammation. Although our understanding of these disease mechanisms has advanced, effective treatments are still limited due to the restrictive nature of the BBB. In this context, nanotechnology has emerged as a promising approach, offering engineered nanocarriers capable of traversing the BBB and enabling targeted drug delivery to the brain. Amongst the various nanomaterials explored, cerium-based nanoparticles have gained particular attention as promising candidates for neurodegenerative disease therapy. Their multifunctionality stemming from reversible redox behaviour, enzyme-mimicking activity, sustained antioxidant effects, and anti-inflammatory properties, combined with their ability to penetrate the BBB and provide neuroprotection, positions them as a powerful platform for future therapeutic strategies. This review begins with a concise overview of the shared pathological mechanisms underlying neurodegenerative diseases, highlights BBB-related drug delivery challenges, and discusses nanocarrier strategies for brain targeting, focusing on cerium-based nanoparticles. We then delved into the structural features, synthesis techniques, and distinctive redox properties of cerium-based nanomaterials, with emphasis on cerium oxide and cerium vanadate. Their therapeutic potential is explored across Alzheimer's and Parkinson's diseases, as well as in stroke, multiple sclerosis, and glioblastoma. Key insights into their physicochemical properties, BBB permeability, and neuroprotective mechanisms are provided. We also address current limitations, including nanoparticle stability, toxicity, and translational barriers, and conclude with future directions for optimizing cerium-based nanozymes in neurotherapeutics.