Biomaterials and Nanoparticle-Based Therapeutics in Neurodegenerative Diseases: Bridging the Gap Between Innovation and Translation.

Neurodegenerative diseases, including Alzheimer's, Parkinson's, Huntington's, amyotrophic lateral sclerosis, and multiple sclerosis, represent a growing global health crisis characterized by irreversible neuronal loss, protein aggregation, chronic neuroinflammation, and mitochondrial dysfunction. Central to their therapeutic intractability is the blood-brain barrier (BBB), a highly selective neurovascular interface that excludes nearly 98% of conventional pharmacological agents from the central nervous system (CNS). Nanoparticle- and biomaterial-based delivery platforms have emerged as promising strategies to overcome these barriers, encompassing liposomes, polymeric nanoparticles, engineered exosomes, inorganic nanoparticles, and hydrogel scaffolds capable of enabling targeted CNS drug delivery. This Review systematically evaluates the landscape of nanomaterial-based neurotherapeutics across disease-specific pathological contexts, critically analyzing translational failure mechanisms including limited parenchymal brain exposure, receptor saturation during transcytosis, protein corona-mediated immune clearance, and nanoscale toxicity in postmitotic neural tissue. Preclinical-to-clinical translational gaps arising from interspecies BBB transporter heterogeneity and pharmacokinetic divergence are examined alongside manufacturing and regulatory barriers impeding Good Manufacturing Practice (GMP)-scale production. Emerging convergence strategies─including AI-integrated design, hybrid physiologically based pharmacokinetic modeling, theranostic nanoplatforms, and wearable bioresponsive delivery systems─are evaluated for their capacity to address these limitations. The review concludes by proposing a framework for developing clinically viable, disease-modifying CNS nanomedicines.