Hu Xuemei, Wei Zixuan, Tang Menghuan, Long Yijuan, Zheng Huzhi
College of Chemistry and Chemical Engineering, Southwest University, Beibei, Chongqing, 400715, China.
Mikrochim Acta. 2020 Aug 6;187(9):489. doi: 10.1007/s00604-020-04468-4.
Lowering the background signal for more sensitive analysis of determinands is as important as amplifying the target signal. The photoinduced oxidase of fluorescein has been reported, which can catalyze the oxidization of common substrates in a few minutes. As a metaphor for locks and keys, we designed double locks confining the activity of fluorescein to reduce the background absorbance during colorimetric detection. The first lock inhibits the main activity of fluorescein by phosphating. The second lock almost completely deactivates fluorescein by forming coordination nanoparticles (CNPs) via the self-assembly of cerium chloride and fluorescein diphosphate (FDP). The Ce-FDP CNPs are characterized by scanning electron microscope (SEM), dynamic light scattering (DLS), Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectrum (EDS), which show electrostatic formation and amorphous character in the morphology. Alkaline phosphatase (ALP), the key to release fluorescein, can destroy Ce-FDP CNPs along with decomposing FDP by degrading phosphate groups. Therefore, a novel colorimetric strategy for sensitive detection of ALP is established. The detection of α-fetoprotein (AFP) is further succeeded by labeling AFP antibody with ALP. By dramatically reducing the background absorbance, the detection limits of ALP and AFP are as low as 0.014 mU/mL and 0.023 ng/mL, respectively. This convenient, brief, sensitive assay provides a promising prospect for clinical diagnosis. Graphical abstract.
降低背景信号以更灵敏地分析被测定物与放大目标信号同样重要。已有报道称荧光素的光诱导氧化酶可在几分钟内催化常见底物的氧化。作为锁和钥匙的比喻，我们设计了双锁来限制荧光素的活性，以降低比色检测过程中的背景吸光度。第一把锁通过磷酸化抑制荧光素的主要活性。第二把锁通过氯化铈和荧光素二磷酸（FDP）的自组装形成配位纳米颗粒（CNP），几乎完全使荧光素失活。通过扫描电子显微镜（SEM）、动态光散射（DLS）、傅里叶变换红外光谱仪（FTIR）、X射线衍射（XRD）、X射线光电子能谱（XPS）和能量色散谱（EDS）对Ce-FDP CNP进行了表征，结果表明其在形态上具有静电形成和无定形特征。碱性磷酸酶（ALP）是释放荧光素的关键，它可以通过降解磷酸基团破坏Ce-FDP CNP并分解FDP。因此，建立了一种用于灵敏检测ALP的新型比色策略。通过用ALP标记甲胎蛋白（AFP）抗体，进一步成功检测了AFP。通过显著降低背景吸光度，ALP和AFP的检测限分别低至0.014 mU/mL和0.023 ng/mL。这种方便、简洁、灵敏的检测方法为临床诊断提供了广阔的前景。图形摘要。
