Recent Advances on Chitosan-Based Nanoparticles for Brain Drug Delivery.

The blood-brain barrier (BBB) represents a major challenge in effective drug delivery systems intended for treating neurological disorders. It restricts the transport of therapeutic agents to the brain. Chitosan-based nanoparticles (CNPs) can be used for brain drug delivery because of their biocompatibility, biodegradability, and ability to enhance drug permeability across the BBB. This review article discusses the design and application of CNPs for brain-targeted drug delivery, exploring their mechanisms of action, including adsorptive-mediated and receptor-mediated endocytosis. Surface modifications with ligands such as chlorotoxin are discussed for improving specificity and therapeutic results. Findings show that CNPs allow controlled drug release, enhance stability, and reduce side effects, which make them effective for treating multiple neurological conditions, including Alzheimer's disease, Parkinson's disease, brain tumors, and ischemic stroke. CNPs can encapsulate multiple therapeutic agents, such as anti-inflammatory drugs, cytotoxic agents, and genetic materials, and maintain stability under different physiological conditions. Intranasal delivery routes are mainly discussed in this paper for their ability to bypass systemic circulation and achieve direct brain targeting. This review also addresses challenges such as cytotoxicity and the need for optimizing nanoparticle size, charge, and surface properties to improve the therapy results. While CNPs are suitable for brain drug delivery, there is a research gap, which is the lack of systematic studies evaluating their long-term effects on brain tissue and health. Most studies focus on acute therapeutic outcomes and in vitro or short-term in vivo analysis, which do not address some questions about the chronic exposure risks, biodistribution, and clearance pathways of CNPs. This review also explores the use of chitosan-based nanoparticles to deliver drugs to the brain for the treatment of multiple neurological disorders.