Abstract: Drug delivery compositions for specific delivery of a drug to a tumor are described. These compositions include a core for sequestering the drug and a shell to which a ligand is attached for delivery of a drug to target cells. Since normal cells may also be targeted by the ligand, the compositions embed the ligand in the shell until the localized conditions surrounding the tumor cause the ligand to be displayed on the surface of the shell. One composition exhibits shrinkage of the shell at tumor pH, whereas another composition exhibits extension of the ligand at tumor pH. Still another composition causes the ligand to be exhibited at an elevated temperature.

Abstract: Mixed micelles containing poly(L-histidine)-poly(ethylene glycol) block copolymer and poly(L-lactic acid)-poly(ethylene glycol) block copolymer are a pH-sensitive drug carrier that release the drug in an acidic microenvironment, but not in the blood. Since the microenvironment of solid tumors is acidic, these mixed micelles are useful for treating cancer, including those cancers exhibiting multidrug resistance. Targeting ligands, such as folate, can also be attached to the mixed micelles for enhancing drug delivery into cells. Methods of making poly(L-histidine), synthetic intermediates, and block copolymers are also described.

Abstract: Disclosed are liquefied embolic materials capable of sol-gel phase transition in response to in vivo conditions, including temperature, ionic strength, and pH, and their uses. The liquefied embolic materials are made of copolymers based on temperature-sensitive isopropylacrylamide and ionic strength- and/or pH-sensitive monomers. In addition to finding excellent applications in the embolotherapy, the embolic materials can be used as extracellular matrixes for cell culture and for drug-delivery systems for cancer therapy.