本研究利用兩種對於Hg2+及Cu2+與酸鹼雙重感測性之螢光單體1-Benzoyl-3-[2-(2-allyl-1,3-dioxo-2,3-dihydro-1Hbenzo[de]isoquinolin-6-ylamio)-ethyl]-thiourea (BNAPTU)及(3-hydroxy-4-methylphenyl methacrylate) Rhod -amine B hydrazone(RB)，將其各別與N-isopropylacrylamide(NIPAAm)、N-hydroxymethylacrylamide(NMA)以自由基聚合法合成不同單體比例之共聚高分子poly(NIPAAm-co-NMA-co-BANPTU (P1、P2, Donor)及poly (NIPAAm-co-NMA -co-RB (P3、P4, Acceptor)，使用靜電紡絲技術將兩種不同高分子混紡成具有螢光能量轉移特性(Förster resonance energy transfer, FRET)高比表面積之奈米纖維，鏈中PNIPAAM為具有親水性，可使纖維於水溶液中膨潤而有利於重金屬離子與螢光感測集團之相互作用；PNMA為奈米纖維之化學交聯鏈段，經過熱交聯後能穩定纖維型態在溶液中保持穩定。
中性環境加入Hg2+後，會誘導BNAPTU結構上的硫脲，形成不可逆的分子內環化反應，造成吸收及螢光放光波長藍移，其螢光顏色從綠色變成藍色。於酸性環境(pH2)加入Cu2+，RB螢光強度會隨Cu2+濃度提高而下降，產生電子轉移，導致螢光淬滅，形成一ON-OFF之螢光感測器。利用靜電紡絲製成之奈米纖維，其高分子鏈在纖維間的距離會較溶液態靠近，因此隨pH值降低，會產生高效之FRET效率，而使螢光放光轉移，其螢光放光顏色會從綠色變為橘紅色，更隨著環境中酸鹼值與重金屬離子組成，其螢光顏色也會有對應之螢光表現，如中性及酸性銅離子之下螢光顏色為綠光、中性汞離子環境之下為藍色、酸性汞離子環境之下為紫色等等，因此結合此FRET機制之奈米纖維將可以作為一種對於pH敏感、汞離子及銅離子感測之新型感測器。

The sensing nanofibers (B1、B2、B3、B4 and B5) were prepared by electrospinning technique from the blending solution of two copolymers [poly(NIPAAm-co-NMA- co-BNAPTU), P1, P2] and [poly(NIPAAm-co-NMA -co-RB), P3, P4] with different compositions. The BNAPTU, RB, NIPAAm, and NMA moieties were designed to facilitate fluorescent sensing for mercury ions, fluorescent sensing for coppor ions and pH, good swelling of the nanofibers in aqueous solution, and thermal crosslinkable moieties to stabilize the fibrous morphology in aqueous solution, respectively.
The nanofibers showed emissive color change from yellowish green to blue in the presence of mercury ions due to the intramolecular cyclization of thioureas in the BNAPTU moieties. The nanofibers could also be used as an ‘‘ON-OFF’’ sensor through PET mechanism after addition of copper ions in acidic environment (pH2), where the intensity of fluorescence was decreased linearly as the concentration of copper ions increased, and the fluorescence emission were changing from red fluorescence to nonfluorescence. The distances between BNAPTU and RB in nanofibers were much closer than those in solution state, therefore, the FRET efficiency will be much higher than that in solution state under the pH diversification, and the fluorescence emission was shifted from green to red. The fluorescence emission color of electrospinning (ES) fiber included green, red, blue and purple depending on the particular pH, copper ions and mecury ions concentration combination of the solution. Thus, the ES nanofibers with FRET mechanism prepared from P2/P4 with on/off swithchable ability characteristics can be used as a multifunctional sensory device for specific heavy metal-ion in aqueous solution.

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