Peripheral Neuronal Biomarkers, REM-Sleep Neurophysiology, and Nanoparticle Drug Delivery: An Integrated Translational Framework for Brain Diagnosis and Therapy

Abstract

Early diagnosis and effective treatment of central nervous system disorders remain constrained by the inaccessibility of brain tissue, the restrictive blood-brain barrier, and the delayed appearance of overt neurological symptoms. This review integrates three rapidly advancing domains that together offer a practical translational pathway for brain medicine: peripheral neuronal biomarkers, sleep neurophysiology, and nanoparticle-enabled drug delivery. Blood- and cerebrospinal-fluid biomarkers such as the amyloid-beta 42/40 ratio, phosphorylated tau isoforms, neurofilament light chain, glial fibrillary acidic protein, ubiquitin carboxyl-terminal hydrolase L1, exosomal cargo, and disease-associated microRNAs now provide minimally invasive windows into neurodegeneration, acute injury, and glioma biology. In parallel, mechanistic studies of rapid eye movement and non-rapid eye movement sleep show that REM architecture, hippocampal replay, spindle-ripple coupling, and glymphatic clearance act as informative physiological readouts of circuit integrity and cognitive vulnerability. Nanoparticle systems—including lipid, polymeric, and magnetic platforms—add the therapeutic dimension by enabling transport of nucleic acids, small molecules, and imaging agents across or around the blood-brain barrier, especially when paired with receptor targeting or focused ultrasound. When considered together, these areas support a stepwise model in which biomarkers identify risk and disease stage, sleep physiology refines timing and mechanistic interpretation, and nanocarriers deliver precision interventions while the same biomarkers track response. The resulting framework is particularly relevant to neurodegeneration, brain injury, and glioblastoma, where earlier detection and more selective delivery are both urgently needed.