金屬有機骨架(Metal－organic frameworks, MOFs)是由金屬節點以及有機小分子連接器所組成的奈米孔洞材料，其具有高比表面積、結構多變性，以及高孔洞性的結構。其中，鋯基金屬有機骨架(Zirconium metal－organic frameworks, Zr-MOF)具有出色的水穩定性，使其能夠應用於需在水相中進行的反應。在過往的報導中，將鋯基金屬有機骨架與導電材料或氧化還原活性位點結合，可應用於電化學多巴胺(DA)感測，並且得到良好的靈敏度及線性範圍。然而，在文獻當中發現，未經修飾的Zr-MOF薄膜相較於裸電極，其DA氧化的法拉第電流訊號可以被略為放大。由於大多數未與導電材料或是活性位點結合的Zr-MOF在DA的氧化電位下是電絕緣體，因此電荷傳導不應該在Zr-MOF薄膜內發生。再者，因為此系統中唯一具有氧化還原活性的只有多巴胺，因此氧化電流的放大效應應該歸因於DA本身的氧化所帶來的電流訊號，此處提出一個假設，多巴胺能夠吸附於Zr-MOF的骨架內，在氧化還原的同時進行電荷傳遞。然而，先前尚未研究過這種現象的起源。
為了瞭解多巴胺在骨架的吸附行為，以及如何造成電流放大效應，本研究中使用具水穩定性的Zr-MOF，UiO-66，透過改變合成溫度來調整UiO-66中的缺陷位置數量，以便研究DA與Zr-MOF中位於缺陷位置的末端官能基-OH/-OH2之間的相互作用。研究結果表明，DA的氧化電流密度隨著Zr-MOF中缺陷位點數量的增加而增加，並且透過實驗證明DA被吸附在UiO-66中，從而產生基於氧化還原跳躍的感測電流。進一步在能夠選擇性感測DA的電化學活性材料(例如氧化石墨烯(Graphene, GO))薄膜上沉積MOF這種多孔的訊號放大器，可以製備具有放大訊號並對常見干擾物具有良好選擇性的電化學DA 感測器。

In this study, a water-stable zirconium-based metal–organic framework (Zr-MOF), UiO-66, is synthesized with a tunable degree of missing-linker defects, and the corresponding crystallinity, morphology, porosity, and degree of defects are characterized. Although all the UiO-66 synthesized here is electrically insulating and electrochemically inactive, the thin film of defective UiO-66 deposited on the electrode surface can significantly amplify the electrochemical sensing signal for DA. The effect of the degree of defects on the resulting sensing response for DA is examined, and the origin of such a signal amplification effect, which is relevant to the hopping-based electrochemical process of the irreversibly adsorbed DA in the defective MOF, is investigated. By serving the defective UiO-66 as a signal amplifier casted on top of another electrically conductive active material capable for selective DA detection, the modified electrode for sensing DA with enhanced performances can be developed. As a proof-of-concept demonstration, the defective UiO-66 thin film was coated on the graphene oxide (GO) modified electrode. With the use of such a bi-layer thin film for DA sensing, a much higher sensitivity (6.4-fold), a much smaller limit of detection, and a better selectivity toward DA against AA and UA can be achieved compared to those of the GO thin film. Experimental results here shed light on the use of such porous MOF coatings to effectively enhance the sensing performances of other developed electrochemical sensing systems for DA.

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