Yongling Du,Min Guo,Yan Chen,Xiaohui Mo,Junlei Cao,Fangdi Hu
Cortisol, a corticosteroid hormone as a primary stress hormone response to internal and external stress, has been regarded as a gold standard reliable biomarker to evaluate human mental stress. The double enzymes strategy, using nanozyme and enzyme amplifying the electrochemical signal, has been widely used to improve the performance of electrochemical biosensors. An ultra-sensitive electrochemical cortisol sensor based on Au single-atom nanozymes had been fabricated through HRP labeled anti-cortisol antibody binding with Au by Au-S bond. Based on the high catalytic activity of Au single-atom nanozymes and the high selectivity of HRP-labeled anti-cortisol antibodies, the cortisol electrochemical sensor-based Au single-atom nanozymes had an excellent response to cortisol, such as high electrochemical activity, high sensitivity, high selectivity, and wide linear range (0.15–300 ng.mL −1 ) and low detection (0.48 pg.mL −1 ) through the four-parameter logistic model with 95% confidence. The electrochemical cortisol sensor was used to determine the cortisol concentration of human saliva at different times.
The ongoing outbreak of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted that new diagnosis technologies are crucial for controlling the spread of the disease. Especially in the resources-limit region, conveniently operated detection methods such as “naked-eye” detection are urgently required that no instrument is needed. Herein, we have designed a novel and facile strategy to fabricate covalent organic framework (COF) capsules, which can be utilized to establish a new colorimetric assay for naked-eye detection of SARS-CoV-2 RNA. Specifically, we employ the digestible ZIF-90 as the sacrificial template to prepare the hollow COF capsules for horseradish peroxidase (HRP) encapsulation. The fabricated COF capsules can provide an appropriate microenvironment for the enzyme molecules, which may improve the conformational freedom of enzymes, enhance the mass transfer, and endow the enzyme with high environmental resistance. With such design, the proposed assay exhibits outstanding analytical performance for the detection of SARS-CoV-2 RNA in the linear range from 5 pM to 50 nM with a detection limit of 0.28 pM which can go parallel to qTR-PCR analysis. Our method also possesses excellent selectivity and reproducibility. Moreover, this method can also be served to analyze the clinical samples, and can successfully differentiate COVID-19 patients from healthy people, suggesting the promising potential in clinical diagnosis.
Li Wenjun,Chen Siyu,Yang Yue,Song Yiju,Ma Chaoyun,Qiao Xiuwen,Hong Chenglin
A GOx/HRP@ZIF-90 nanomaterial is proposed by coating GOx and HRP in ZIF-90 using a bio-simulated mineralization method to improve the tolerance of the enzyme to the external environment. In the detection process, the ZIF-90 is turned on under mild conditions by the competitive reaction of ATP with Zn 2+ and imidazole-2-carboxaldehyde (2-ICA), and the electrical signal of the system is amplified by the enzyme cascade reaction of GOx and HRP. Finally, based on the signal amplification strategy of the competitive reaction between Zn 2+ and ATP to construct a “signal on” mode, electrochemical immunosensor of GOx-HRP enzyme–linked cascade reaction was prepared. The proposed electrochemical immunosensor shows an excellent analytical performance when detecting CA-125, with good selectivity and stability, with a detection range of 0.1 pg mL −1 –40 ng mL −1 and a detection limit of 0.05 pg mL −1 . The test has been performed using chronoamperometry under a constant voltage of −0.4 V. The immunosensor also shows an excellent performance when analysing human blood samples. The recovery of the immunosensor is 97.94–101.8%, with a relative standard deviation of 3.7–6.1%. The proposed sensor provides a novel idea for clinical use of GOx and HRP enzymes and a new method for the clinical detection of tumor markers. Graphical abstract
危险品化学品经营许可证（带存储）