Combining of Thermoresponsive Copolymer Microgels and Magnetic Materials for Used in Hyperthermia and Drug Delivery systems
Date Issued
2007
Date
2007
Author(s)
Su, Chia-Hong
DOI
zh-TW
Abstract
This study is divided into four parts. In the first part, the precursors FeCl3．6H2O and FeCl2．4H2O was dissolved in water and then alkali was added to synthesis magnetite nanoparticles by co-precipitation method. The distribution of particle size, surface potential, morphology, lattice structure and magnetic properties of these particles were compared with commercial magnetite. From the results, the size of magnetite were all about 20nm by using different kind’s of alkali. Due to the electric and steric repulsion effect, the size distribution was varied so much, especially the magnetite which used N(CH3)4OH as the alkali. And from the SQUID analysis, the one which use N(CH3)4OH as the alkali could be obtained 60 emu/g magnetization and as higher as the commercial one. According to previous research, the higher the magnetization, the higher the heat efficiency.
At the second part, we used N-isopropylacrylamide (NIPAAM), acrylic acid (AAc) and 2-hydroxyethyl methacrylate (HEMA) as the monomer, N,N’-methylenebis acrylamide (MBA) as the cross-linking agent and Potassium persulfate (KPS) as the initiator to prepare thermoresponsive copolymer microgels by using surfactant-free emulsion polymerization. To reach the goal of the drug delivery temperature, we changed the copolymer molar ratio and further discussed their size distribution, morphology, thermal properties, thermal and pH responsibility. From the the TEM, the size was measured about 500~600 nm；the glass transition temperature changed with different copolymer ratio；low critical solution temperature (LCST) was increasing obviously with increasing HEMA and AAc monomer ratio and then reach the goal of drug releasing temperature-40℃. For pH effect, pH = 7 for HEMA system and pH = 9 for AAc system could get good swelling ratio. NMR spectrum couldn’t be used to calculate the copolymer ratio because some of the characteristic peaks were not find, that may due to the concentration of cross-linking agent was too high.
By combining the above two parts , we prepared the magnetic microgels by using some chemical bonding of magnetite and thermoresponsive copolymer microgels. The hysteresis loss effect resulted from applying a magnetic field to the magnetite can be used as the thermoresponsive switch, and thus the drug delivery by microgels can be achieved by the change of its morphology. From TEM and TGA results, we can find that only AAc system could encapsulate the magnetite well by in in–situ because the chemical bonding between carboxylate group and Fe2+ and Fe3+ .
Finally, the magnetic microgels was tested on heating and drug delivery. By applying the magnetic field, the magnetite produced heat by hysteresis loss, if the temperature can reach 42~43℃, the magnetic microgels may be used as hyperthermia. At the same time, the thermoreponsive copolymer microgels would change its morphology and release drug by increasing the temperature. Under 150A, 80.53kHz, 50mg/Ml, the temperature increased about 5~6℃ and reach to the goal temperature of hyperthermia for magnetic microgels but not for only thermoresponsive copolymer microgels. Indocyanine Green (ICG) and Methylene Blue (MB) were be choosing as the drug to do the release test. From the results, the heat produced by hysteresis loss could be used as the temperature switch and release drug about 80~90% of total quality of drug. .We hope this study can combine the properties of two materials to develop the new therapy technology and improve the side effect of drug loader and increase the drug releasing efficiency.
Subjects
丙烯酸
共聚溫感性微乳膠
共沉澱法
藥物釋放
甲基丙烯酸二羥基乙酯
氮-異丙基丙烯醯胺
acrylic acid
copolymer microgels
co-precipitation method
2-hydroxyethyl methacrylate
hyperthermia
N-isopropylacrylamide
thermoresponsive drug delivery
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-96-R94549006-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):d1a428f3a0c4c0131da2cab1119d1c8c