Synthesis And Characterizations Of Poly(N-isopropylacrylamide)-g-Polyamidoamine

The poor solubility of hydrophobic drugs in water and their low dissolution rate in the body fluids often leads to insufficient bioavailability and is one of the most difficult and non-dissolved problems in pharmaceutical industry. Over the years, various solid dosage formulation techniques including solid dispersion,β-cyclodextrin inclusion complex, water-soluble prodrug et al., which enhance the dissolution of poorly soluble substances, have been successfully introduced to some extent. However, some of the formulated drug systems become instable and will recrystallize when they are stored for a period of time.The aim of this work was to explore a new drug carrier Poly(N-isopropylacrylamide)-graft-PAMAM dendrimers. The PAMAM have the hydrophobic core which the hydrophobic drugs can be entrapped into, while the poly(N-isopropylacrylamide) have the thermosensitive properties, which could control the delivery of the drugs. This kind of the new drug carrier can be desirable to increase the solubility of the hydrophobic drugs and control the release the drugs.First, PMAMA dendrimers were synthesized by the divergent growth method and characterized by FT-IR and 1H-NMR. Sencond, Using mercaptoacetic acid (MAA) as a chain-transfer agent, the radical oligomerization of N-isopropylacrylamide (NIPAm) was carried out with varying molar ratios of MAA to NIPAm in methanol.Using 2-Aminoethanethiol hydrochloride(AET?HCl) as a chain-transfer agent, the amine-terminated PNIPAm was also obtained using the same method. The structure of the therosensitve polymers was characterized by FT-IR and 1H-NMR. The molecular weight was determinated by 1H-NMR, end group titration and gel permeation chromatography (GPC). Third, PNIPAm with different terminal reactive groups was grafted to the PAMAM dendrimers using EDC?HCl. The structure of the therosensitve polymer-grafted dendrimer was characterized by FT-IR and 1H-NMR.The molecular weight was determinated by GPC. The therosensitve properties was determined by UV-VIS photometer. The LCST was changed with different medium. This kind of new drug carrier was desirable to make a great effect in the drug delivery area.