Preparation And Self-assembly Based On N-isopropylacryamide Glycopolymer And Its Release Property Of Drugs

Due to the nanometer dimensions and unique core-shell structures, polymeric micelles, microgel and nanofibers as novel drug delivery systems have attracted growing attentions in biomedical material field in recent years. On the basis of numerous published research work, we designed and synthesized a series of novel poly(N-isopropylacrylamide)-based thermoresponsive polymeric materials as intelligent drug carriers, and investigated their thermoresponsive properties and in vitro drug release behaviors in detail.Chapter1presents a detailed review of recent progress in biomedical polymeric materials, drug delivery systems and PNIPAAm-based polymeric micelles, microgels and nano fibers. The following research contains three chapters:Chapter2Novel double-hydrophilic thermosensitive statistical glycopolymers, poly(N-isopropylacryamide-co-6-O-vinyladipoyl-D-glucose)(NIPAAm-co-OVAG) were fabricated using a chemoenzymatic process and radical copolymerization. The structures of the glycopolymers were confirmed by1H NMR and13C NMR, and their molar mass distributions determined by gel permeation chromatography (GPC). The self-assembly and critical aggregation concentration (CAC) were verified by fluorescence spectroscopy with pyrene acting as a hydrophobic probe. The UV-vis data showed that the double-hydrophilic glycopolymers exhibited reproducible temperature-responsive behavior. Measurements by laser light scattering (LLS) and transmission electron microscopy (TEM) revealed that the glycopolymers were able to self-assemble into aggregates with varying particle sizes and morphologies in aqueous solutions.Chapter3Novel galactose functionalized thermoresponsive injectable microgels, P(N-isopropylacryamide-co-6-O-vinyladipoyl-D-galactose) P(NIPAAm-co-VAGA) were fabricated using a combination of enzymatic transesterification process and emulsion copolymerization. The structures of the microgels were confirmed by Fourier transform infrared (FTIR). The UV-vis data showed that the microgels exhibited reversible temperature-responsive behavior, by alternating the monomer feed ratio, copolymers were synthesised to have their own distinctive lower critical solution temperature (LCST). The particle size in aqueous, deswelling ratios and morphology of the microgels were measured by dynamic light scattering (DLS) and transmission electron microscopy (SEM). The in vitro drug release indicates that drug release rate, encapsulation efficiency (EE) and release kinetics depend upon the temperature and copolymer composition. According to this study, the microgels based on P(NIPAAm-co-VAGA) could serve as suitable candidate for drug site-specific carrier in liver.Chapter4Novel thermosensitive glycopolymers nanofibers, poly(6-O-vinyladipoyl-D-glucose-co-N-isopropylacryamide) P(NIPAAm-co-OVAG) were fabricated using a electrospinning method. In this work, we integrate double-hydrophilic thermosensitive random glycopolymers, enzymatic transesterification and electronspinning to achieve our goals of fabricating smart and targeted copolymer, and presented the first study of electrospinning ultrathin fibers made from the resultant copolymers. Oral fast-dissolving drug delivery membranes (FDMs) for poorly water-soluble drugs were prepared via electrospinning technology with ibuprofen as the model drug and P(NIPAAm-co-OVAG) as the filament-forming polymer and drug carrier. The ibuprofen-loaded fiber membrane was dissolved very rapidly once the membrane touched water. The average dissolution time for the fiber membrane was about4±1.5s.