聚甲基丙烯酸二羥基乙酯應用於亞硝酸根離子檢測之光纖探針開發

聚甲基丙烯酸二羥基乙酯(poly(2-hydroxyethyl methacrylate), pHEMA)的水膠特性有助於溶液進入，而不失其原本的外部形狀，並且具有良好的透光率與生物相容性。以上特性使 pHEMA 作為常見的隱形眼鏡原料，亦可作為良好的光學生物感測器材料。本研究使用自由基聚合搭配總體聚合方式，在光纖的端頭上製作出直徑 1 mm 的水膠圓柱，成為一光纖探針。pHEMA 在本研究中有幾個重要功能，其一為感測分子的載體，不讓光纖探針在放入待測溶液時，發生洩漏進而汙染待測溶液。並且可以直接附著於光纖端頭上，不須額外黏接過程。在聚合前於反應物中加入感測分子，照光或加熱後製成直徑 1 mm 的 pHEMA 雙光纖探針。本研究目前使用 1,2-Diaminoanthraquinone(DAQ)做為感測分子，此分子能夠與一氧化氮及酸性環境下的亞硝酸根反應生成 DAQ-TZ，DAQ 與 DAQ-TZ 有顯著的吸收光譜差異。藉由反應中吸收光譜的變化，可推算溶液中的一氧化氮或亞硝酸根濃度。由於一氧化氮在溶液中的濃度不易控制，故此處使用亞硝酸根離子溶液作為感測目標，目前達到 10-2M 的感測極限。在未來研究中將釐清本聚合方法製成的 pHEMA，在不同環境下的特性，並嘗試改良聚合方式，降低本光纖探針的感測極限。建立水膠聚合的光纖探針範本，以利後續適用更多種的感測分子。

關鍵字

水膠；亞硝酸根離子；自由基聚合；總體聚合

並列摘要

The poly(2-hydroxyethyl methacrylate )(pHEMA) is a kind of hydrogel, which has a good property to let the solution get into it without losing its original shape. It also has good light transmittance and biocompatibility. The above characteristics make pHEMA a common contact lens material and can also be used as a good optical biosensor material. In this study, a free radical and bulk polymerization method were used to fabricate a cylinder with a diameter of 1 mm on the end of a fiber to serve as a fiber-optic probe. pHEMA plays two important roles in this work. It serves as a carrier for the sensing molecules and as a support structure, which can be attached to the fiber tip without additional adhesive. Sensing molecules were added to the reaction solution, which was then polymerized by either UV exposure or thermal heating to form a pHEMA fiber-optic probe with a diameter of 1 mm. In this study, 1,2-Diaminoanthraquinone (DAQ) was used as a sensing molecule, which can react with nitric oxide in neutral environment and nitrite in an acidic environment to form DAQ-TZ. The concentration of nitric oxide or nitrite in the solution can be estimated by the change in the absorption spectrum due to significant absorption difference between DAQ and DAQ-TZ. The nitrite ion solution was used here as a sensing target, and a sensing limit of 10-2 M can be achieved. To summarize, a fabrication processes for fiber-optic sensing probe was developed for both UV and thermal polymerization. The synthesis protocol for pHEMA can be further optimized to improve the polymer properties and reduce the sensing limit. Different sensing probes can be incorporated into the pHEMA for various applications.