Nanoparticles for Crossing the Blood–Brain Barrier in Alzheimer's Disease Treatment

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and behavioral changes. One of the primary challenges in developing effective treatments for AD is the blood–brain barrier (BBB), a selective, semipermeable membrane that restricts drug entry into the central nervous system. Nanotechnology has emerged as a groundbreaking approach to bypass this barrier, providing innovative solutions for the targeted, efficient, and minimally invasive delivery of therapeutic agents into the brain. This review examines recent advancements in nanoparticle-based drug delivery systems designed to treat AD. Different types of nanocarriers, including metallic nanoparticles, polymeric systems, solid lipid nanoparticles, liposomes, and dendrimers, have shown significant promise in transporting drugs across the BBB. These systems enhance drug bioavailability, allow for controlled release, and help minimize systemic toxicity. By functionalizing nanoparticles with targeting ligands and modifying their surface properties, their ability to penetrate the brain and improve therapeutic outcomes is further optimized. Additionally, green-synthesized nanoparticles and the encapsulation of natural compounds offer eco-friendly, biocompatible alternatives, broadening the possibilities for AD treatment. This review also discusses key mechanisms, such as receptor-mediated and adsorptive-mediated transcytosis, employed by nanoparticles to cross the BBB. Finally, the challenges, potential toxicity issues, and future directions for the clinical application of these nano-therapeutics are also addressed. The integration of nanotechnology into AD treatment strategies presents a promising frontier for managing the disease and potentially developing disease-modifying therapies.