Brain is the most complex organ in human body. It has an intercellular filtration system, which allows very few materials to enter into the cells

Brain is the most complex organ in human body. It has an intercellular filtration system, which allows very few materials to enter into the cells, thus making it difficult for drugs and indicators to enter into the neuron with a rare chance of cure.Cy5.5 can filter through this system easily and illuminates the starting and ending of a tumor.