bra in ▁bar rier . ▁Research ▁is ▁being ▁conducted ▁to ▁investigate ▁new ▁methods ▁of ▁target ing ▁the ▁brain ▁using ▁the ▁blood ▁supply , ▁as ▁it ▁is ▁much ▁easier ▁to ▁inject ▁into ▁the ▁blood ▁than ▁the ▁sp ine . ▁New ▁techn ologies ▁such ▁as ▁nan ote chn ology ▁are ▁being ▁research ed ▁for ▁select ive ▁drug ▁delivery , ▁but ▁these ▁techn ologies ▁have ▁problems ▁as ▁with ▁any ▁other . ▁One ▁of ▁the ▁major ▁set back s ▁is ▁that ▁when ▁a ▁particle ▁is ▁too ▁large , ▁the ▁patient ' s ▁li ver ▁will ▁take ▁up ▁the ▁particle ▁and ▁deg rade ▁it ▁for ▁ex cret ion , ▁but ▁if ▁the ▁particle ▁is ▁too ▁small ▁there ▁will ▁not ▁be ▁enough ▁drug ▁in ▁the ▁particle ▁to ▁take ▁effect . ▁In ▁addition , ▁the ▁size ▁of ▁the ▁cap ill ary ▁p ore ▁is ▁important ▁because ▁too ▁large ▁a ▁particle ▁might ▁not ▁fit ▁or ▁even ▁plug ▁up ▁the ▁hole , ▁prevent ing ▁ade qu ate ▁supply ▁of ▁the ▁drug ▁to ▁the ▁brain . ▁Other ▁research ▁is ▁involved ▁in ▁integr ating ▁a ▁protein ▁device ▁between ▁the ▁layers ▁to ▁create ▁a ▁free - flow ing ▁gate ▁that ▁is ▁un imp eded ▁by ▁the ▁limitations ▁of ▁the ▁body . ▁Another ▁direction ▁is ▁re ceptor - medi ated ▁transport , ▁where ▁re cept ors ▁in ▁the ▁brain ▁used ▁to ▁transport ▁nut ri ents ▁are ▁manip ulated ▁to ▁transport ▁dru gs ▁across ▁the ▁blood – bra in ▁bar rier . ▁Some ▁have ▁even ▁suggested ▁that ▁focused ▁ul tras ound ▁opens ▁the ▁blood – bra in