Signal "Off-On Model'' for Colorimetric Sensing Proanthocyanidin B₂ Achieved by the Organic Solvent-Processed...

Area of Science:

• Materials Science: Development of novel nanomaterials for sensing applications.
• Analytical Chemistry: Design of sensitive and selective colorimetric detection methods.

Background:

• Traditional nanozymes often require hydrogen peroxide (H2O2) for catalytic activity.
• Amorphous nanomaterials offer unique defect structures and properties compared to crystalline counterparts.
• Polyphenols, like proanthocyanidin B2, are important antioxidants with health benefits, requiring accurate quantification.

Purpose of the Study:

• To develop a peroxide-free colorimetric sensor based on amorphous bismuth vanadate (BiVO4) nanoparticles.
• To investigate the catalytic activity and sensing mechanism of dual-defect amorphous BiVO4 for polyphenols.
• To establish a sensitive and specific sensor platform for proanthocyanidin B2 detection.

Main Methods:

• Synthesis of amorphous BiVO4 nanoparticles via organic solvent processing.
• Characterization of material defects (vanadium and oxygen vacancies) and oxidase-like activity.
• Development of an 'off-on' colorimetric assay using TMB as a substrate and polyphenol analysis.

Main Results:

• Amorphous BiVO4 nanoparticles exhibit dual vacancies (Vv and Ov) and single oxidase-like activity.
• The sensor demonstrates a signal-intensified colorimetric response for polyphenols, accelerating TMB oxidation.
• A sensor for proanthocyanidin B2 achieved a low limit of detection (65 nM), outperforming the Porter method.

Conclusions:

• The developed amorphous BiVO4 nanozyme provides a robust and sensitive platform for peroxide-free polyphenol detection.
• This 'off-on' model sensor exhibits high specificity and accuracy, validated in commercial grape seed capsules.
• The general applicability of this method suggests potential for sensing various reducing polyphenols.