A dual-biomimetic MOF integrated with a hydrogel microfluidic chip for dual-mode polyphenol detection.

The detection of polyphenols is critical for safeguarding nutritional quality and human health. A microfluidic device incorporating a dual-biomimetic sensing medium for both colorimetric and fluorescence detection of polyphenols was developed in this work. Microwave-assisted heating was employed for the synthesis of Fe-Cu MOF. Subsequently, a film of molecularly imprinted polymer was deposited onto its surface via spontaneous polymerization. Fe-Cu MOF and Fe-Cu MOF@MIP featured both excellent peroxidase-like activity and fluorescence properties. The Fe-Cu MOF core provides peroxidase-like catalytic activity, while the imprinted polymer shell furnishes specific recognition cavities, endowing the system with synergistic catalytic-recognitive capability. Thereafter, nanozyme hydrogels and 3D-printed microfluidic chips were prepared to design biosensors for rapid detection of polyphenols. Using this platform, total polyphenols and three individual polyphenols (GA, punicalagin and ellagic acid) in pomegranate peel (PPe) were successfully detected, with colorimetric detection limits below 32 nmol/L and fluorescence detection limits below 21 nmol/L. Based on the dual-biomimetic design, the platform achieved highly sensitive and rapid on-site visualization of polyphenol monitoring.