Study On The Synthesis Of Chitosan-g-polylactic Acid And Its Releasing Properties Of5-Fluorouracil

The purposes of drug-releasing were prolonged the acted time, improving thefrequency of drug, achieving targeted therapy by natural/synthetic polymer material loadingor adsorbing drugs and importing in the body in the way of pharmaceutical. Therefore, thecarrier of release drug with CS and PLA as the raw material were favored by manyresearchers.The PLA with reactive side group were synthesized by melt polycondensation fromL-lactic acid, TDI, and the CS-g-PLA were synthesized via coupling polymed to the aminoof CS from PLA-NCO and CS; Structures and morphology of CS-g-PLA were characterizedby IR,1H NMR and Ubbelodhe viscometer;5-fluorouracil (5-FU) loaded CS-g-PLA wereprepared by double emulsion method, and studied for drug content and loading efficiency invitro.The main work and results in the thesis were as follows：1. The white PLA with low viscosity-average molecular weight was prepared by meltpolycondensation in and PLA-NCO with reactive side group was synthesized under anitrogen atmosphere, stepped heating conditions.2. The CS-g-PLA was prepared from chitosan and PLA-NCO by chitosan aminomodified method. The structure of CS-g-PLA were characterized by IR and1H NMR andsome influencing factors, dissolving properties and morphogr were investigated. The bestpreparation the condition of CS-g-PLA is the feed ratio11:1(the mass ratio of PLA-NCOand CS in reaction), the temperature90℃, and the grafting rate reached its maximum97.86%，the time3hours; the dissolve performance tests showed that the strongly hydrogenbonds of CS were changed and the good compatibility were between CS and organicsolvent.3.5-fluorouracil(5-FU) loaded CS-g-PLA microspheres were prepared by double emulsion method, studied for drug loaded and released efficiency in vitro. The resultsindicated that the load efficiency of CS-g-PLA microspheres with certain pH sensitivitcould be decreased to4.04%.The CS-g-PLA microspheres had high susceptibility to pH；Itwas found that the CS-g-PLA microspheres could provided sustained release of5-FU over a50-hours, thus it mean there were fewer medicine.