Syntheses Of Biodegradable Amphiphilic Block Copolymers For Drug Delivery

The micellar self-assembly of biodegradable amphiphilic block copolymers in aqueous solution is of considerable interest because of their self-assembly characteristics and biomedical applications. The distinctive amphiphilic character of the block copolymers enables them to aggregate into versatile micelles in selective solution. These block copolymer micelles can work as novel carrier systems in the field of drug targeting due to their disposition characteristics in the body and the solubilization of the hydrophobic drugs in their inner core.It is well known that a preferred polymeric drug delivery system should be biocompatible, biodegradable, and permeable. poly(ε-caprolactone) (PCL) and its copolymers has been widely investigated in biomedical applications due to its nontoxicity, slow degradation, high permeability to many drugs, and low cost. As a class of biodegradable polymers with repeated phosphoester linkages in the backbone, polyphosphoesters (PPE) with pentavalent phosphorus allowing introduction of bioactive molecules and modification of its chemical and physical properties have received considerable attention. It has been demonstrated that PPE have potential applications in drug and gene delivery due to their favorable biocompatibility, biodegradability, and relatively controllable hydrophilicityFirst, we synthesize Y-shaped biodegradable amphiphilic block copolymers, [poly(ε-caprolactone)]-block-[poly(ethyl ethylene phosphate)]2, (PCL-(PEEP)2). The structure and composition of resulting polymers were demonstrated by NMR, FTIR and GPC. The self-assemble of the polymers in aqueous solution was confirmed by DLS, AFM and 1H NMR. The self-assembling character of the PCL-(PEEP)2 was investigated and the obtained micelles were also studied for drug delivery.Second, cationic polymer has attracted much attention for gene delivery. Here an amphiphilic tri-block copolymer PEG-PCL-PDMAEAM was synthesized by combining a ring-opening polymerization and an ATRP living radical polymerization. NMR, IR, DLS and AFM measurements reveals the formation of the desired coplymer and the relative micelle. We also investigated the micelles for siRNAdelivery.