Expert opinion on current challenges and future directions of nanocarriers for brain targeted drug delivery

Nanomedicine is a rapidly developing field in which nanoparticles or nanostructures are used for medical purposes. The potential of multifunctional nanocarriers (NCs) to cross the blood–brain barrier (BBB) is considerable, particularly in the impoverished field of brain-targeted drug delivery. NCs must overcome a variety of molecular, chemical, and physical barriers in order to enter the brain. The most difficult challenge is designing and developing NCs that explicitly target the subset of diseased neurons while causing no harm to healthy neurons. This is critical, especially when it comes to delivering radioactive drugs to extremely invasive brain tumors. Targeting NCs to attack a tiny proportion of the body's cells is difficult enough without the added complication of the BBB. The microvasculature of the brain is extremely constrictive, whereas the permeation across the blood vessels in many other tissues is considerably greater. The reason behind this is that unregulated infiltration of NCs or compounds into neurons involved in memory, personality, senses, and movement could cause alterations. For the very first time, nanomedicine allows us to develop solutions with less adverse reactions, regulated drug release, targeted delivery, and increased drug bioavailability at the target site. If delivery of drugs to the brain for the treatment of cerebral cancer is to be successful, a clear grasp of the complicated processes which take place on the nanocarriers’ surface, and also in cell-nanocarrier interaction with various transit tissues and organs, is necessary. This chapter discusses the challenges faced by NCs for brain-targeted drug delivery and what the future holds for it.