One of the most demanding fields for pharmaceutical and biotechnological products is the drug delivery to the central nervous system. According to the World Health Organization, 6.8 million people die every year with neurological disorders. All the drug delivery plans to the brain are restricted by the Blood-Brain Barrier (BBB) which limits the therapeutic drug from reaching the targeted site thus exhibiting poor therapeutic effects. The blood brain barrier is a stealth barrier that protects the brain, and allows the entry of few compounds into the brain and functions towards the maintenance of brain homeostasis. The Blood brain barrier site expresses transporters that precisely control permeation of circulating solutes including drugs. The BBB confines drug delivery by generally allowing only those molecules that are lipophilic and have low molecular weight (less than 400-500 Da). It has been reported that approximately 98% of small molecules and nearly all large therapeutic molecules, such as MABs, antisense oligonucleotides, or viral vectors, cannot pass through this barrier. Because of these reasons, delivery of drugs to the brain is still a major challenge, and recent reports designate that less than 10% of therapeutic agents for neurological diseases enter clinical trials because of poor brain penetration.