No abstract

In cancer therapy, surface engineering of drug delivery systems plays an essential role in their colloidal stability, biocompatibility and prolonged blood circulation. Inspired by the cell membrane consisting of phospholipids and glycolipids, a zwitterionic phosphorylcholine functionalized chitosan oligosaccharide (PC-CSO) was first synthesized to mimic the hydrophilic head groups of those amphipathic lipids. Then hydrophobic stearic acid (SA) similar to lipid fatty acids was grafted onto PC-CSO to form amphiphilic PC-CSO-SA copolymers. Cell membrane-mimetic micelles with a zwitterionic surface and a hydrophobic SA core were prepared by the self-assembly of PC-CSO-SA copolymers, showing excellent stability under extreme conditions including protein containing media, high salt content or a wide pH range. Doxorubicin (DOX) was successfully entrapped into polymeric micelles through the hydrophobic interaction between DOX and SA segments. After fast internalization by cancer cells, sustained drug release from micelles to the cytoplasm and nucleus was achieved. This result suggests that these biomimetic polymeric micelles may be promising drug delivery systems in cancer therapy.

No abstract

A novel amphiphilic copolymer, poly (ethylene glycol)-graft-polyethyleneimine/amide (PEG-g-PEI/amide), is synthesized by grafting PEG and1,2-cis-Cyclohexanedicarboxylic anhydride onto the PEI. PEGylated polymeric micelles can be assembled from the amphiphilic copolymers with well-defined nano-sizes, and anti-cancer drugs are successfully loaded into micelle core formed by the amide. The amides with neighboring carboxylic acid groups exhibit pH-dependent hydrolysis and can reversibly shield the cationic charge of amine groups on the PEI, giving the micelles a charge-conversion property from negative to positive in acidic tumor tissue environment. Meanwhile, the cleavage of amide bonds at acidic pH also results in the disassembly of the micelle and pH-responsive drug release. These micelles are promising drug delivery systems due to their smart properties: PEGylation, suitable size, charge-conversion, and simultaneous pH-sensitive drug release.