The Mechanism of Action of Drug Delivery by Polymeric/lipid Carrier

The mechanism of action of drug delivery by polymeric/lipid carrier systems across the BBB could be attributed to:

A) the increased retention of the carrier system in the brain capillaries along with sustained adsorption of the capillary walls creating a higher concentration gradient that would enhance the transport of drug across the endothelial cell layer and as a result its delivery to the brain.
B) the use of surfactants,which could aid in the solubilization of endothelial cell membrane lipids leading to membrane fluidisation and enhanced drug permeability at the BBB
C) the ability of the carrier system to facilitate an opening of the tight junctions between the endothelial cells. The drug could then permeate through the tight junctions either in free form or together with the nanoparticles.
D) the engulfment of the whole carrier system into the cell. The nanoparticles may be endocytosed by the endothelial cells followed by the sustained and/or controlled release of the drug within these cells
E) Any of the above