| Summary: | 博士 === 國立臺灣科技大學 === 化學工程系 === 106 === The emergence of nanoscience and nanotechnology has led to a large number of research activity in these exciting and rapidly growing fields with many potential applications, spanning from energy and environmental sustainability to health care. In the last two decades, a large number of nanostructured materials displaying unique properties has been synthesized and studied whereas electrospun nanofibers are of great importance due to their large surface area to volume ratio, excellent mechanical properties, and tunable porosity and surface characteristics. In the present study, a hydrophilic and biodegradable synthetic polymer, poly(N-vinylpyrrolidone) (PVP), was transformed into smooth and bead-free fibers with average diameters ranging from 72 21 and 550 50 nm through electrospinning. The electrospinning parameters including polymer solution concentration, applied voltage, and the tip-to-collector distance were investigated in relation with the morphological structure and average diameter of the PVP fibers being produced. Three different types of solvents (i.e., methanol, ethanol, and water) and their binary mixtures (i.e., methanol/water and ethanol/water) were used to prepare the electrospinning dopes and the effects of the solvent properties on the electrospinnability and morphological structure of the resulting PVP fibers were also studied.
The second part of this dissertation describes the preparation and surface functionalization of PVP fiber mat for controlled drug release application. The use of electrospun fibrous materials as a drug carrier could be promising in the future for a wide range of biomedical applications, such as wound dressings. Curcumin (CUR) has a wide spectrum of biological and pharmacological activities, yet problems of its bioavailability remained a major challenge in preclinical studies. In this regard, the design of the delivery systems with CUR as a model drug featuring dual release process – an initial burst followed by sustained release – to provide the optimal drug pharmacokinetics in the therapeutic region has been actively pursued. The 3-aminopropyltriethoxysilane (APTES)-functionalized PVP fibers (NH2-PVP) were employed as a free-standing substrate for immobilization of CUR-PVP-capped gold nanoparticles (CUR-PGNPs) conjugates. The CUR-PGNPs conjugate was synthesized by sonication and the drug entrapment percentage was found to be 54.2 1.8. CUR-PGNPs immobilized on NH2-PVP fibers showed a moderate burst release during the first few hours, followed by a sustained release lasting for 2 days. The drug release was also found pH-dependent (pH 5.0 > 6.0 > 7.4). The two-stage release profiles of CUR-PGNPs@NH2-PVP fibers were fitted well to Korsmeyer-Peppas model, indicating a non-Fickian diffusion mechanism for initial burst release and Fickian diffusion-controlled mechanism for the sustained release. Initial biocompatibility assessments based on the lactate dehydrogenase (LDH) release assay and morphological examination by a scanning electron microscope (SEM) with L-929 mouse fibroblasts revealed that CUR-PGNPs@NH2-PVP scaffold was capable of supporting cell growth over a culture period of 3 days.
The third part of this dissertation describes the fabrication of electrospun fiber mats decorated with plasmonic nanoparticles for analytical application. In the past few years, the application of the electrospun nanomaterials to surface-enhanced Raman spectroscopy (SERS) is a rapidly evolving field which holds potential for future developments in the generation of portable plasmonic-based detection platforms. In this dissertation, a simple approach to fabricate electrospun PVP mats surface decorated with gold nanoparticles (AuNPs) by combining electrospinning and calcination processes was presented. AuNPs were synthesized by the citrate reduction method and further immobilized on the fiber mat surface through electrostatic interactions between positively charged aminosilane groups and negatively charged AuNPs. The size and coverage density of AuNPs on the PVP fiber mats could be tuned by varying calcination temperatures. Calcination of AuNPs-decorated PVP mats at 500-700 C resulted in the uniform decoration of high density AuNPs with very narrow gaps on every single fibers, which in turn contribute to strong electromagnetic SERS enhancement. The robust free-standing AuNPs-decorated PVP mat calcined at 500 C (hereafter denoted as 500/AuNPs-F) exhibited high SERS activity toward cationic (methylene blue, MB) and anionic (methyl orange, MO) dyes in single and binary systems with a detection range from tens of nM to a few hundred M. The proposed fiber-based SERS substrate exhibited high reproducibility with the spot-to-spot variation in SERS signal intensities was 10% and 12% for single and binary dye systems, respectively. The determination of MB and MO in spiked river water and tap water with 500/AuNPs-F substrate gave satisfactory results in terms of the percent spike recoveries (ranging from 92.6 to 96.6%) and reproducibility (%RSD values less than 15 for all samples).
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