以仿酵素奈米碳點進行焦磷酸鹽之無金屬檢測

Abstract

焦磷酸鹽的檢測在人體關節相關疾病的診斷上扮演著極為重要的角色，然而以往所採用的檢測方法大多利用金屬離子與焦磷酸根間之螯合作用進行間接性之偵測。在此篇研究中，我們結合了奈米碳點的螢光和仿酵素特性，設計出一套不需引入金屬離子即可進行焦磷酸鹽檢測的方法。研究中所使用的奈米碳點係藉由醣類和氨基酸間之米拉德反應以一步迴流水熱法合成，此奈米碳點不但具有藍色螢光且同時帶有仿酵素催化之特性，可進行鄰苯二胺的氧化反應催化，生成黃色的氧化態產物。由於此產物的吸收光譜和奈米碳點的螢光放光光譜間具有極佳的重疊性，因而導致奈米碳點的螢光放光會因內濾鏡效應的產生而發生被遮蔽的現象。藉由奈米碳點表面的官能基與焦磷酸根之特定作用力，奈米碳點表面的電子轉移過程會被阻斷，抑制其仿酵素特性與接續的黃色氧化態產物生成，進而大幅減低內濾鏡效應之影響，並恢復奈米碳點的螢光放光。藉由此機制，我們便可利用奈米碳點具有仿酵素與螢光探針的雙重功能，達到簡單且直接的焦磷酸鹽之無金屬檢測。

Detection of pyrophosphate ion (PPi) is of great importance due to its crucial role in arthritic related diseases diagnosis. Herein, a straightforward PPi sensing strategy based on peroxidase mimetic property of carbon dots (CDs) is demonstrated. The fluorescent CDs were synthesized by Maillard reaction between sugar and amino acid through a one step refluxing hydrothermal method and the produced CDs possess unique peroxidase mimetic properties. This type of CD can catalyze the oxidation of o phenylenediamine to form a yellow colored product which can act as an absorber to shield CD fluorescence emission via inner filter effect. The specific affinity between PPi and CD surface functional groups blocks CD active centers for electron transfer and can inhibit its peroxidase activity. The formation of absorber is therefore prohibited and the fluorescence emission of CDs recovers with the presence of PPi. A metal free fluorescence turn-on assay for PPi detection can consequently be built by this dual function nanozymatic CD.