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  • 學位論文

含芘基之螢光靜電紡絲纖維於pH及DNA感測器之研究

Preparation of Pyrene-containing Fluorescent Electrospun Nanofibers for pH and DNA Sensing.

指導教授 : 陳靜誼
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摘要


靜電紡絲是近年來用在製備多功能性高分子奈米纖維的新穎技術,相較於微米等級的纖維或薄膜形態,靜電紡絲奈米纖維因大幅度提高纖維的表面積/體積比 (surface-to-volume ratio),更適合於感測元件應用。本研究之目的為製備具芘基(pyrene, PY)的螢光靜電紡織奈米纖維,並將此應用於感測pH及DNA,探討在不同感測環境下PY螢光變化與纖維形態之關係。本實驗利用自由基聚合法 (Free radical polymerization) 合成兩系列不同比例的共聚高分子 poly((2-(dimethylamino)ethyl methacrylate)-co-(stearyl acrylate)-co-((1-pyrene)methyl 2-methyl-2-propenoate) (poly(DMAEMA-co-SA-co-PY))和poly((2-(diisopropylamino)ethyl methacrylate)-co-(stearyl acrylate)-co-((1-pyrene)methyl 2-methyl-2-propenoate) (poly(DPA-co-SA-co-PY)),其中DMAEMA和DPA皆具有酸鹼應答的特性,此性質能使其於酸性環境中高分子鏈上的胺基帶有正電荷,造成奈米纖維在形體上有膨潤-收縮的效應,而此膨脹-收縮會使共聚的PY單體間距離改變,導致其有excimer和monomer螢光發光的轉換,因此我們可以從螢光的發光或形體的變化得知高分子鏈上的胺基帶電與否,但當酸鹼應答高分子轉換成親水基團時,奈米纖維於水溶液中將無法維持原有形體,所以我們將物理交聯劑(SA)共聚在高分子中,以維持電紡纖維結構。在電紡實驗中,我們將高分子溶液加入BTEAC(5%)以增加電紡溶液的導電性,並得到較佳的纖維形態(300~400nm)。再以SEM和FL觀察其兩系列的電紡纖維的形體與螢光變化,其中Poly(DPA-co-SA-co-PY) (Pp3:DPA:SA:PY=89 : 5 : 6)的電紡纖維,在pH5下其纖維由原有的333nm膨脹到1579nm,而在螢光光譜中excimer/monomer(460nm/378nm)的比值,在pH7時為1.09,而在pH5時下降到0.48,由這兩種數據中可說明高分子鏈中的胺基在酸性溶液中逐漸帶有正電荷,使得奈米纖維在靜電斥力和物理交聯劑的交互作用下,其纖維逐漸膨脹但又能維持住纖維的形體,由於高分子鏈中PY單體之間的距離改變,導致其比值下降,接著將帶有正電荷的奈米纖維用以感測DNA,從SEM和FL可以觀察到纖維直徑收縮到479nm且excimer/monomer ratio上升到0.78,此表示我們成功利用胺基上的正電荷吸附帶有負電荷的DNA;而Poly(DMAEMA-co-SA-co-PY) (Pm3:DMAMEA:SA:PY= 79 : 14 : 7)的電紡纖維,其形體也隨著pH下降而膨脹,由FL觀察到excimer/monomer的比值,在pH7時為2.24,而在pH5時下降到0.77,而感測DNA時,由SEM可看出電紡纖維有明顯的收縮,excimer/monomer的比值為1.04。此外與薄膜相較,由FL觀察到Pp3和Pm3的薄膜形態其pH7到pH5的excimer/monomer比值差異,皆均較奈米纖維形態的感測器為低。以上結果顯示,此兩系列之功能性靜電紡絲纖維有做為pH及DNA感測器的潛力。

並列摘要


Electrospinning (ES) has emerged as uniquely convenient technique for producing continuous nanofibers because it has the advantages of low cost, tunable morphology, and high-throughput continuous production. Among its wide applications, ES nanofibers with high surface-area-to-volume ratio and sensing functionality have the potential to utilize in sensory devices. We successfully prepared two series of pH-sensitive and luminescent electrospun (ES) nanofibers for sensing DNA via free radical polymerization: poly((2-(dimethylamino)ethyl methacrylate)-co-(stearyl acrylate)-co-((1-pyrene)methyl 2-methyl-2- propenoate)) (poly(DMAEMA-co-SA-co-PY)) and poly((2-(diisopropylamino) ethyl methacrylate)-co-(stearyl acrylate)-co-((1-pyrene)methyl 2-methyl-2-propenoate)) (poly(DPA-co-SA-co-PY)). The moieties of DMAEMA/DPA, SA, and PY were designed to exhibit the pH-responsive, physical cross-linking, and fluorescent functionality, respectively. The random copolymers with different molar ratios were utilized for preparation of ES nanofibers using a single-capillary spinneret. Pp3 copolymer with the DPA/SA/PY mole ratio of 89/5/6 showed a significant pH-dependent swelling and de-swelling behavior, and the diameter was changing from 333 nm to 1579 nm in pH5. Accompanied with volume-changing on the Pp3 ES fibers, the excimer/monomer emission ratios of 460 nm/397nm were gradually quenching from 1.09 to 0.48 during the decrease in pH value from 7 to 5. In addition, the prepared Pm3 copolymer with the DMAEMA/SA/PY mole ratio of 79/14/7 also showed a significant pH-dependent swelling and de-swelling behavior. The excimer/monomer emission ratios at 471 nm/397nm were gradually quenching from 2.24 to 0.77 with decreasing pH value from 7 to 5. These ES nanofibers were further used for sensing DNA. The SEM and FL spectra exhibited the de-swelling of nanofibers and increase of the excimer/monomer ratios in pH 5 due to the electrostatic interaction between quanternay amine from copolymers and negative charged phosphate groups from DNA. The results indicate the pyrene-based ES nanofibers would have the potential applications for DNA sensory devices.

參考文獻


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