A fluorescence method for the quantitative detection of chloramphenicol (CAP) has been developed using phosphate and fluorescent dye 6-carboxy-x-rhodamine (ROX) double-labeled aptamers of CAP and the bimetallic organic framework nanomaterial Cu/UiO-66. Cu/UiO-66 was prepared by coordinate bonding of metal organic framework (MOF) nanomaterial UiO-66 with copper ions. Cu/UiO-66 contains a large number of metal defect sites, which can be combined with phosphate-modified nucleic acid aptamers through strong coordination between phosphate and zirconium to form “fluorescence turn-on” sensors. In the absence of CAP, all single-stranded aptamers were adsorbed on the surface of Cu/UiO-66 through π-π stacking between single-stranded DNA and Cu/UiO-66, which brings the ROX fluorophores and Cu/UiO-66 into close proximity. The ROX fluorescence of aptamers was then quenched by Cu/UiO-66 through photoinduced electron transfer (PET). In the presence of CAP, however, CAP reacted with nucleic acid aptamers to form a special spatial structure, in which the ROX fluorophores were far away from the MOF surface via a change in the spatial structure of the aptamers, and the fluorescence of ROX was able to be recovered. The quantitative detection of CAP can be achieved by measuring the fluorescence signal of ROX using synchronous scanning fluorescence spectrometry. Under optimum conditions, the fluorescence intensities of ROX exhibit a good linear dependence on the concentration of CAP in the range of 0.2–10 nmol/L, with a detection limit of 0.09 nmol/L. The method has advantages of high sensitivity, good selectivity, and a low limit of detection.

Graphical abstract

已经开发了一种荧光方法，用于定量检测氯霉素（CAP），使用磷酸和荧光染料CAP的双羧基适体和双金属有机骨架纳米材料Cu / UiO-66进行6-羧基-x-罗丹明（ROX）双标记。通过金属有机骨架（MOF）纳米材料UiO-66与铜离子的配位制备Cu / UiO-66。Cu / UiO-66包含大量金属缺陷位点，可通过磷酸盐和锆之间的强配位作用与磷酸盐修饰的核酸适体结合，形成“荧光开启”传感器。在没有CAP的情况下，所有单链适体通过单链DNA与Cu / UiO-66之间的π-π堆积吸附在Cu / UiO-66的表面上，这带来了ROX荧光团和Cu / UiO-66紧密接近 适体的ROX荧光然后通过光诱导电子转移（PET）被Cu / UiO-66淬灭。然而，在存在CAP的情况下，CAP与核酸适体反应形成特殊的空间结构，其中ROX荧光团通过适体的空间结构变化而远离MOF表面，并且ROX的荧光为能够被恢复。CAP的定量检测可以通过使用同步扫描荧光光谱法测量ROX的荧光信号来实现。在最佳条件下，ROX的荧光强度对CAP浓度在0.2-10 nmol / L范围内表现出良好的线性依赖性，检出限为0.09 nmol / L。该方法具有灵敏度高，选择性好，检测限低的优点。

图形概要