RESUMEN
Electron transfer is considered to be a typical parameter that affects the catalytic activity of nanozymes. However, there is still controversy regarding whether higher or lower electron transfer numbers are beneficial for improving the catalytic activity of nanozymes. To address this issue, we propose the introduction of Pd doping as an important electron regulation strategy to tune electron transfer between Pt and ZIF-8 carriers (PtxPd1@ZIF-8). We observe a volcano-shaped relationship between the electron transfer number and catalytic activity, reaching its peak at Pt4Pd1@ZIF-8. Mechanism studies indicate that as the electron transfer number from Pt to ZIF-8 carriers increases, the d-band center of the active site Pt increases, reducing the occupancy of antibonding states and enhancing the adsorption capacity of the key intermediate (*O). However, a further increase in the adsorption of *O energy makes it difficult to desorb and participate in the next reaction, thus exhibiting volcanic activity. The optimized Pt4Pd1@ZIF-8 nanozyme is applied to develop an immunoassay for the detection of zearalenone, achieving a detection limit of 0.01 µg/L, which is 6 times higher than that of the traditional enzyme-linked immunosorbent assay. This work not only reveals the potential regulatory mechanism of electron transfer on the catalytic activity of nanozymes but also improves the performance of nanozyme-based biosensors.
Asunto(s)
Estructuras Metalorgánicas , Paladio , Platino (Metal) , Catálisis , Platino (Metal)/química , Paladio/química , Estructuras Metalorgánicas/química , Transporte de Electrón , Inmunoensayo/métodosRESUMEN
In the presented study, a horseradish peroxidase (HRP)-mediated ratiometric fluorescence enzyme-linked immunosorbent assay (ELISA) for zearalenone (ZEN) was reported based on fluorescence quenching of gold-silver bimetallic nanoclusters (Au-Ag NCs). HRP-antibody was used as a bridge in this immunoassay, linking the ratiometric fluorescence signal to the ZEN concentration. HRP catalyzed the oxidization of o-phenylenediamine in the presence of H2O2, leading to the formation of 2,3-diaminophenazine, which not only delivered a new peak at 580â¯nm but also quenched Au-Ag NCs fluorescence at 690â¯nm. Under optimal conditions, the detection limit for the proposed ELISA was 0.017â¯ng/mL, which was approximately 6.6-fold lower than conventional ELISA. Moreover, analytical performances were evaluated fully including specificity, accuracy, precision, and practicability, and showed that this method provides a potential platform for sensitive and reliable detection of ZEN.
Asunto(s)
Ensayo de Inmunoadsorción Enzimática/métodos , Oro/química , Peroxidasa de Rábano Silvestre/metabolismo , Nanopartículas del Metal/química , Plata/química , Zearalenona/análisis , Fluorescencia , Peróxido de Hidrógeno/química , Nanopartículas del Metal/ultraestructura , Espectrometría de Fluorescencia/métodosRESUMEN
Zearalenone (ZEN) has a potential hazard to human health, and is frequently found in agro-products. To minimize ZEN exposure to consumers, a novel metal-organic framework-based immunoassay system using zeolitic imidazolate framework-encapsulated horseradish peroxidase and goat anti-mouse IgG (HRP/Ab@ZIF-L) as labels was proposed for rapid and ultrasensitive detection of ZEN in agro-products. The HRP/Ab@ZIF-L not only maintained recognition ability of antibody and catalytic activity of enzyme, but also protected encapsulated proteins against high temperature, organic solvents and long term storage. Under optimal conditions, the detection limit of HRP/Ab@ZIF-L-based immunoassay reached 0.5 ng/L for ZEN, which was approximately 126-fold lower than that of conventional HRP-based immunoassay. Moreover, the proposed method showed an excellent selectivity, and a good dynamic linear detection for ZEN in the range of 0.5 ng/L to 0.476 µg/L. The recoveries of ZEN from spiked corn and wheat samples ranged from 84.50% to 96.70% with the relative standard deviation under 8.9%. In brief, the proposed immunoassay method has potential application for rapid and ultrasensitive detection of ZEN in agro-products.