Jie Liu,Zixuan Zhang,Jie Dong,Anyi Chen,Jingfu Qiu,Chaorui Li
As a reliable biomarker to evaluate the severity of sepsis, sensitive and accurate detection of procalcitonin (PCT) is essential. In this study, a dual-mode electrochemical immunosensor based on Au/ZIF-8 as substrate and Pt@Cu 2 O as signal label was constructed for the detection of PCT. By loading Au nanoparticles onto rhombic dodecahedral ZIF-8, the substrate (Au/ZIF-8) has large specific surface area and can immobilize antibody (Ab 1 ) by Au–N bonds. Meanwhile, hollow Pt@Cu 2 O nanocomposite with excellent peroxidase-like activity and electrocatalytic activity were synthesized as signal label. In the process of electrochemical testing, Pt@Cu 2 O catalyzed the reduction of hydrogen peroxide (H 2 O 2 ) and further promotes the oxidation of hydroquinone (HQ) to achieve the synergistic amplification of electrochemical signals. The proposed immunosensor detected PCT by amperometric i-t and differential pulse voltammetry (DPV) tests with a good linear response and low limit of detection (i-t: 0.70 fg/mL and DPV: 0.40 fg/mL) in the range of 10 fg/mL∼100 ng/mL. The immunosensor exhibited excellent sensitivity and accuracy, indicating the potential application of this method for PCT detection.
Exploring signal amplification strategies to enhance the sensitivity of lateral flow immunoassay (LFIA) is of great significance for point-of-care (POC) testing of low-concentrated targets in the field of in vitro diagnostics. Here, a highly-sensitive LFIA platform using compact and hierarchical magneto–fluorescent assemblies as both target-enrichment substrates and optical sensing labels is demonstrated. The large-pored dendritic templates are utilized for high-density incorporation of both superparamagnetic iron oxide nanoparticles (IOs) and quantum dots (QDs) within the vertical channels. The hierarchical structure is built via affinity-driven assembly of IOs and QDs from organic phase with silica surface and mercapto-organosilica intermediate layer, respectively. The sequential assembly with central–radial channels enables 3D loading of dual components and separately controlling of discrete functionalities. After the alkyl-organosilica encapsulation and silica sealing, the composite spheres exhibit high stabilities and compatibility with LFIA for procalcitonin (PCT) detection. With the assistance of liquid-phase antigen-capturing, magnetic enrichment, and fluorescence-signal amplification, a limit of detection of 0.031 ng mL −1 for PCT is achieved with a linear range from 0.012 to 10 ng mL −1 . The current LFIA is robust and validated for PCT detection in real serum, which holds great diagnostic significance for precise guidance of antibiotic therapy with POC manner.
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