Physiological characteristics of the liver The liver is an important organ involved in the processes of digestion, excretion, detoxification and immunity. Liver diseases are common clinical diseases, such as viral hepatitis, cirrhosis and liver cancer, which are extremely harmful to human health. The liver-targeted drug delivery system is an important way to explore an effective treatment method for liver disease, as it enriches the drug at the site of the liver lesion to exert the curative effect, reducing the amount of drug and the number of drug administration. Liver cells are divided into hepatic parenchymal cells, Kupffer cells and endothelial cells, of which parenchymal cells are the main cells that make up the…

The blood-brain barrier (BBB) is a barrier system that exists between the blood system and the brain tissue, and is mainly composed of polarized intercellular tight junctions of polarized brain capillary endothelial cells (BCECs). It maintains a relatively stable internal environment for brain tissue, guarantees the normal physiological function of the central nervous system (CNS), and transports nutrients to the brain; but at the same time, its existence also hinders the drug of diagnosis and treatment  into the brain.  About 98% of small molecule drugs and almost 100% of macromolecular drugs, including proteins, peptides and gene drugs, cannot be directly delivered into the brain by peripheral administration, which is a…