本論文主要在近場電紡絲技術中，研究纖維的形成、發展控制技術以及應用，主要重點為(1)近場電紡絲技術中可控制的幾丁聚醣/聚氧化乙烯（chitosan/poly(ethylene oxide)）之奈米纖維沉積及排列，(2)利用電壓調節所製作出近場電紡絲技術的選擇性沉積，(3)近場電紡絲技術所生產的奈米纖維觀察細胞型態與擴散狀況。(1)近場電紡絲技術中可控制的幾丁聚醣/聚氧化乙烯之奈米纖維沉積及排列 在本篇中近場電紡絲技術已證明可將幾丁聚醣之奈米纖維達到控制及良好排列之成果。良好控制、排列之近場電紡絲幾丁聚醣奈米纖維有利於操作細胞最佳附著位置。實驗結果中表明，透過調整近場電紡絲技術的各種參數，奈米纖維直徑可以準確地控制在265-1255 nm之範圍內；並且將纖維排列圖案達成方格陣列和圓弧形狀，在精準的排列中將最小之間距控制至500 μm的尺度，並使用FTIR測量其材料性質。運用此項技術將幾丁聚醣/聚氧化乙烯製造可控制及定向排列的奈米纖維，並擁有高度控制為指定的圖案，這代表此生物材料將在組織工程支架將有一席發展之地，尤其是能代表細胞外基質（extracellular matrix）。(2) 利用電壓調節所製作出近場電紡絲技術的選擇性沉積 此篇章節利用電壓調節應用於近場電紡絲技術得到持續縮減尺寸的幾丁聚醣/聚氧化乙烯奈米纖維。電壓調節之關鍵參數在於1-3秒內將電壓從800V降至400V，且將直徑縮減從1000-250 nm。並使奈米纖維控制間距於100 μm，且排列成平行及方格陣列之圖形。電壓調節的近場電紡絲技術能盡量減少高電壓範圍時，所產生的噴射彎曲不穩定性；及高分子噴射期間移動平台震動時所產生的機械擾動，而達到將奈米纖維沉積不穩定達到準確可控制之最佳化狀態。另外，已經成功地使用連續不斷之奈米纖維於二維（2D）和三維（3D）基板上的可行性。(3) 近場電紡絲技術所生產的奈米纖維觀察細胞型態與擴散狀況 本篇章節講述近場電紡絲技術已證明能夠將幾丁聚醣/聚氧化乙烯奈米纖維沉積成規定的圖案及定位密度。並可觀察到平行排列的奈米纖維間距在20和100 μm時，可以引導細胞的擴展方向，並利用二進制圖像及快速傅立葉轉換測量細胞的生長方向及對齊程度，研究中指出細胞之生長方向與奈米纖維之間的排列方式有重大的影響。這些低成本、快速製作的製程未來可以有效運用於細胞貼附、擴散等議題。This thesis mainly research formation of nanofiber, controlled technology and application in near-field electrospinning. The focus of the study is (1) Direct-write, well-aligned chitosan-poly(ethylene oxide) nanofibers deposited via near-field electrospinning, (2) Controlled continuous tapering nanofibers using a differential voltage regulation in near-field electrospinning process, (3) Direct-write, highly-aligned chitosan-poly(ethylene oxide) nanofiber patterns for cell architecture/ morphology and spreading control.(1) Direct-write, well-aligned chitosan-poly(ethylene oxide) nanofibers deposited via near-field electrospinning.A continuous near-field electrospinning (NFES) process has been demonstrated to be able to achieve direct-write and well-aligned chitosan/poly(ethylene oxide) nanofibers. The ability to precise control and deposit chitosan-based nanofibers in a direct-write manner is favorable in manipulating cells attachment and proliferation at preferred position. Experimental results show that fiber diameters can be reliably controlled in the range of 265-1255 nm by adjusting various operating parameters of the NFES processes. These prescribed patterns of nanofibers exceed tens of centimeters long and complex configurations such as grid arrays and arc shapes are assembled at specified separations as small as 5 μm. FTIR analysis reveals that NFES nanofibers have a similar morphology and composition as conventional electrospinning counterpart and constitute all components formerly present in the polymer solution. The versatile functionality to fabricate chitosan-based nanofibers with controllable size and directional alignment as well as highly ordered and customized patterns may represent an ideal candidate of a functional biomaterial and in tissue-engineering scaffolds that are predominantly representative of extracellular matrix (ECM).(2) Controlled continuous tapering nanofibers using a differential voltage regulation in near-field electrospinning process.This thesis reports a differential voltage regulation (DVR) via near-field electrospinning (NFES) to obtain continuous tapering chitosan-poly(ethylene oxide) nanofibers with decreasing diameters of 1000 to 250nm. The key parameters were applied differential voltage in the range of 800 to 400V and voltage regulation time at 1-3 seconds. A controlled continuous deposition chart has been experimentally constructed and parallel nanofibers as well as grid patterns with decreasing diameters are successfully obtained via the low-voltage operation of 400V. Both DVR and low-voltage regime minimize bending instabilities and patterning perturbations of polymer jet inevitably encountered in higher voltage ranges of conventional far-field electrospinning. In addition, we have successfully demonstrated the feasibility to continuously pattern nanofibers on two-dimensional (2D) and three-dimensional (3D) substrates. This novel yet simple fabrication route will promise the use of electrospun nanofibers based interconnection and customized patterning for advanced fabrics such as biomimic scaffolds in tissue engineering.(3) Direct-write, highly-aligned chitosan-poly(ethylene oxide) nanofiber patterns for cell morphology and spreading controlNear-field electrospinning (NFES) has been demonstrated to be able to achieve direct-write and highly-aligned chitosan nanofibers (CNF) with prescribed positioning density. Cells spreading in preferential direction could be observed on parallel aligned nanofibers and the CNF patterns were capable of guiding cell extension, when the distances between them are 20 and 100μm, respectively. Alignment of the cells was characterized by elongation and orientation of the cells via the FFT data and binary image analysis. Parallel CNF indicates the alignment values sequentially increased as a function of the positioning density such that incrementally more aligned cells were closely related to the increasing CNF positioning density. These maskless, low-cost and direct-write patterns can be facily fabricated and will be a promising tool to study the cell-based research such as cell adhesion, spreading and tissue architecture.
