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Etching reaction-based photoelectrochemical immunoassay of aflatoxin B1 in foodstuff using cobalt oxyhydroxide nanosheets-coating cadmium sulfide nanoparticles as the signal tags
摘要： A new split-type photoelectrochemical (PEC) immunosensing platform was designed for sensitive detection of aflatoxin B1 (AFB1) in foodstuffs, coupling with enzymatic hydrolysate-triggered etching reaction of cobalt oxyhydroxide (CoOOH) on cadmium sulfide (CdS) nanoparticles-functionalized interface. Initially, the photosensitive electrode was prepared by coating CoOOH nanosheets on the surface of CdS nanoparticles to quench the photocurrent. Thereafter, a competitive-type enzyme immunoreaction was carried out on monoclonal anti-AFB1 antibody-conjugated magnetic bead by using alkaline phosphatase (ALP)-labeled bovine serum albumin-AFB1 (AFB1-BSA) conjugate as the competitor. With the formation of immunocomplex, the carried ALP hydrolyzed ascorbic acid 2-phosphate (AAP) into ascorbic acid (AA) and phosphate. The former ascorbic acid produced etched or dissolved CoOOH nanosheets into Co2+ ions, thus resulting in the exposure of CdS nanoparticles on the surface to enhance the photocurrent of the modified electrode. Under optimum conditions, the photocurrent decreased linearly with the increasing AFB1 concentration in the dynamic range of 0.01 – 10 ng mL-1, and the limit of detection was 2.6 pg mL-1. The precision of this method (expressed as RSD) was ± 8.6%. In addition, the accuracy was monitored by analyzing spiked food samples, and gave the well-matched results with the referenced ELISA method.
关键词： cobalt oxyhydroxide nanosheets,cadmium sulfide nanoparticles,aflatoxin B1,photoelectrochemical immunoassay,etching reaction
更新于2025-09-04 15:30:14
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First Principle Calculations of Optical Properties of CdS:Al system (A DFT+U study)
摘要： In current research, we perform a computational study to calculate optical properties of Al doped CdS system for 1 × 1 × 2, 2 × 2 × 1, 2 × 2 × 2 supercell configurations and for DFT+U (1 × 2 × 2). Cd atoms are substituted with Al atoms and the result for optical properties shows significant changes in the case of 2 × 2 × 1 supercell configuration. This study has been executed with PBE-GGA and GGA+U approaches, used in Wien2K code employed within the framework of DFT. In comparison to 1 × 1 × 2 supercell configuration, optical absorption for 2 × 2 × 1 supercell configuration and DFT+U shows blueshift while for 2 × 2 × 2 redshift is observed. Study explore that optical properties are enhanced and absorption increases in visible region. Hence, Al doping into host CdS lattice suggest that opto-electrical properties are enhanced which advocate candidacy of this material for nanotechnology and optoelectronic devices.
关键词： DFT calculations,Density of states,Al-doping,Cadmium sulfide,Optical properties
更新于2025-09-04 15:30:14