One Pot To Prepare Functional Copolymers By Chemoenzymatic And The Study Of Self-assembly And Drug Delivery Behavior

Chemoenzymatic synthesis combining the ATRP advantage of active controllable,efficient, lots of reactive functional monomer, many polymer segments can bedesigned etc. and eROP advantage of green environmental protection, mild reactionconditions, the enzyme can be recycled, the product has the stereo selectivity andbiocompatible etc. in one. Further more, the one pot method simplified the reactionprocess which makes the jumbled multistep reaction becomes easier to operationand shorter reaction time.This method if applicated in industrial it will not only savesthe purification process of the intermediate product but also can greatly improve theyield, saving the cost and reduce the pollution of reagent. The combining ofchemoenzymatic and one pot method not only provides a efficient and convenientway for the preparation of multifunctional block polymer, but also laid the foundationfor the application in practical production. Functional block copolymers in thesolution can through self-assembling behavior become nanoparticles with specificmorphologies and structures such as vesicles and micelles. Construct target groups inpolymer nanoparticles and using these nanoparticles in loading of drugs to treatspecific diseases is the current development direction of functional polymers and hasa future practical prospect.In this paper we used several methods to synthesis all kinds of copolymers withvarious different structure and function, such as diblock, triblock, H-shaped and brushcopolymer. We also explored the potential applications of the copolymer wesynthesized at the same, characterize the structure and properties of copolymer andstudy the drug release behavior of the polymer micelles. In chapter two, we through a bifunctional initiator EBiB initiate the ATRP reactionof BMA at the same time initiate another enzymatic self-condensation reaction of10-HD in one pot, with this method we synthesized diblock copolymerPBMA-b-P(10-HD). In order to verify the structure, we through hydrolysis reaction todissociate the P(10-HD) segments, then we characterized the structure of the blockcopolymer by tests such as NMR, IR, GPC to identify the molecular weight andproved that the one pot reaction was successed. The critical micelle concentration ofthe diblock copolymer was studied by using pyrene as fluorescent probe molecules,the results shows a relatively low CMC value because of the two segments of thecopolymer is mostly hydrophobic. Through the DLS, AFM and TEM test, themorphology of the nanoparticles in aqueous solution were measured. The results showthat the polymer nanoparticles are spherical micelles in aqueous solution with ahydrodynamic diameter at about310nm, and in the dry state of the other two kinds oftest we got a relativelt smaller results. The10-HD segments in the copolymer has theproperties of crystallization, so we investigated the crystallization properties of thecopolymer. The results shows that the polymer has a good crystalline properties,polarizing microscope in dark field can observed the crystal progress clearly and withthe phenomena of Maltese cross. From the DSC test, we got the melting temperatureand crystallization temperature of the copolymer were respectively Tm=67.6℃andTc=51.3℃, the crystallization enthalpy of the crystal process was27.7J/g.In chapter three, we through a special initiator3-Butyn-1-ol to induced the enzymaticself-condensation reaction of10-HD, prepared polymer P(10-HD) with alkyneterminated, then we use2-bromopropiomyl to modified the P(10-HD) to prepared themacroinitiator, click chemistry of PEG-N3and ATRP reaction of4-vP was happenedat the same time by one pot method. pH sensitive amphiphilic triblock copolymersPEG-b-P(10-HD)-b-P4VP was synthesized. Through a series of routine test wecharacterized the structure and molecular weight of the triblock copolymer. Proof oursuccess with synthsis the triblock copolymer. We studied the crystallization propertiesof the copolymer because of the existence of p(10-HD) and PEG segments, the results show that the polymer can form the spherulitic crystallization, but due to theinterference of amorphous chain segments of P4VP, leading to the formation ofspherulites is not very regular, we calculated the growing rate of the copolymercrystallinity by fitting linear mapping was0.286nm/s. In addition, we alsoinvestigated self-assembly behavior of the pH sensitivity amphiphilic copolymerPEG-b-P(10-HD)-b-P4VP in aqueous solution, the CMC value is0.011mg/mL.Through DLS, AFM and TEM, we investigated the size and morphology of thetriblock copolymer micelles in solution, and studied the effect of pH on the polymermicelles. We found that because of4-vinyl pyridine can capture a large number ofH+and be protonated in acidic conditions, so the hydrodynamic diameter decreasesfrom226nm to169nm when in neutral environment(pH=7) than in the acidicenvironment(pH=3). Protonated pyridine ring also can form hydrogen bonds, so thatsome of the polymeric micelles have a phenomenon of aggregation.In order to verify the application value of our functional copolymers prepared, inchapter four, we use2-bromobutyrate to initiate the ATRP reaction of GMA, PGMAwere prepared. After the epoxy groups on PGMA was attacked by sodium azide, amolecule PHAZPMA with azide groups and hydroxyl groups was prepared. In orderto ensure the solubility of polymers in the following experiment we first modifiedPEG segments by click chemistry on the side chain of PHAZPMA, made a graftcopolymer PHAZPMA-g-PEG. Histidine is a pH response molecules we chosen,considered likely to play an excellent performance in the polymer drug carrier system,was modified to the side chain of the graft copolymer. Through the IR, NMR, GPCand other conventional tests, we characterize the polymer molecular weight andstructure, we proved the success of the experiment. Through the study of histidinemodification rate, we chose the best one with appropriate modification ratePHAZPMA-g-PEG (His) for the subsequent experiments. The self-assembly behaviorof the graft copolymers in aqueous solution was studied and the CMC value weobtained was0.012mg/mL with the hydrodynamic diameter of194nm, due to the drystate AFM and TEM results will be smaller. Through physical interaction anticancer drug doxorubicin hydrochloride was directly embedded, we prepared polymer micelledrug carrier system PHAZPMA-g-PEG(His)@DOX, and the drug release behavior ofthe system is studied. The results show that the drug delivery system has a goodsustained-release effect, the pH value and temperature changes will have a great effecton the drug release process.In chapter five, we use2,2-dichloroethanoyl modified PEG to prepare a H-shapedmacroinitiator, then initiate the ATRP reaction of HEMA we synthesized H-shapedblock copolymer (PHEMA)2-b-PEG-b-(PHEMA)2, control the ratio of material weprepared many groups of different molecular weight of H-shaped block polymer andstudied the properties in aqueous solution of these copolymer. We chose the one withmore excellent properties of aqueous solution to modified by histidine. The specialstructure of copolymer has made its chains have better ductility in space, effectivelyreduces the space resistance of histidine molecules, and finally have a highermodification rate as far as50%than those linear polymers in chapter four. By theconventional tests such as IR, NMR, GPC etc, we characterized H-shaped amphiphilicblock copolymer ((His)PHEMA)2-b-PEG-b-(PHEMA(His))2and proved thesuccessfully reaction. Through the study of the self-assembly behavior in aqueoussolution, we obtained the CMC value of the copolymer is0.011mg/mL, because of thestrong hydrophobicity exhibited of histidine imidazole ring in neutral environment.,so that a small CMC value is according with the objective reality. The DLS showes ahydrodynamic diameter of184nm, which also larger than AFM and TEM that wehave already discussed. Embedding DOX we prepared polymer micelle medicinecarrying system ((His)PHEMA)2-b-PEG-b-(PHEMA(His))2@DOX, through therelease progress in different pH and temperature. We found that at lower pH valueand higher temperature, release quantity and the release rate are bigger and faster, thisis because of the properties of polymers, and on the other hand also relative by DOX’sown properties.