Synthesis And Properties Of Amphiphilic Supramolecular Copolymer Micelles Based On The Multiple Hydrogen Bonds

With the rapid development of modern medicine,research deepening of biomedical polymer materials,biodegradable polymers were widely used in drug delivery systems.Because of the stable performance and the adjustable and controlled features of the physical and chemical properties,it has been achieved more and more attention from researchers.Block polymers made of Poly(ethylene glycol)and polycaprolactone often appear in drug delivery systems,not only because they both have excellent biodegradability,but also has an excellent biocompatibility in order to avoid easily being recognized by the immune system of body.Poly(ethylene glycol)can also reduce the adsorption of proteins in the material surface in vivo.Poly(ethylene glycol)and polycaprolactone are both approved by the U.S.Food and Drug Administration(FDA),and as biological material are widely used in biomedical applications.And there have a relatively acidic environment around the tumor cells,it can be used as a signal,which thereby triggering micelles loaded drug to quickly release drug.This paper is based on these characteristics,hydrogen bonds,which has the extremely sensitive nature to the acidic environment were used in the synthesis of functional polymers.Novel supramolecular copolymer micelles prepared were successfully prepared through the complementary multiple hydrogen bonds between uracil and diamino triazine.It could be wrote down like MPEG-U:DAT-PCL,and the characterization of the micelles were studied.First,both uracil-terminated polyethylene glycol(MPEG-U)and diamino triazine-terminated poly(?-caprolactone)(PCL-DAT)were prepared,and according to the different feed ratio of initiator and monomer we can obtain the polymer PCL-DAT with adjustment of the composition.The structure and characteristic of the polymer were confirmed by FT-IR,1H NMR,and GPC.The amphiphilic supramolecular polymer MPEG-U:DAT-PCL micelles were prepared based on multiple hydrogen bonds.The supramolecular amphiphilic polymer were proved to successfully self-assemble into micelles with PCL core and PEG shell using fluorescence probe method.The critical micelle concentration(CMC)of the micelles is between 5.1×10-4 mg/mL to 7.1 × 10-4mg/mL,with the growth of the hydrophobic segment PCL the critical micelle concentration decreased.The dynamic light scattering(DLS)method was used to determinated particle size and distribution of micelles at the concentration of 0.05mg/mL.With the hydrophobic segment(PCL)reduced micelle size increased.DLS method was taken not only to determinate the particle size and distribution of micelles in different pH condition,but also to study the change of the particle size and distribution over time in the pH=5 condition.Micelle morphology in different pH condition was studied through transmission electron microscope(TEM),which turned out to be spherical shape.