Targeted Protein Degradation and Delivery Strategies in the Context of Neurological Disorders.

Neurological disorders represent a leading cause of global mortality and disability, yet treatment options remain limited due to the challenges of targeting pathogenic proteins, particularly those considered "undruggable" by conventional small molecules. Targeted protein degradation (TPD) has expanded the druggable proteome by harnessing proteasomal and lysosomal pathway to eliminate these targets, offering the advantages of lower toxicity and reduced resistance compared to traditional modulation. This review systematically delineates TPD mechanisms according to their degradation pathways, including proteasomal, endosomal-lysosomal, and autophagy-lysosomal systems, and highlights their unique applications in brain diseases. However, the translation of TPD to neurological disease is limited by physicochemical liabilities, cell-type dependence, risks associated with whole-protein ablation, the blood-brain barrier (BBB) and poor brain bioavailability. To address these translational barriers, we emphasize the integration of TPD with drug delivery systems (DDS) as a pivotal strategy. By optimizing pharmacokinetics, stability, and BBB penetration, nano-DDS significantly enhances brain targeting and therapeutic precision. Finally, we evaluate recent progress in nano-TPD systems and offer critical insights into their future trajectory in treating complex brain disorders.