Dual-functionality in one MOF: Tailored AuNC@MOF hybrids with synergistic oxidase-mimetic activity and fluorescence amplification for multi-modal tannic acid sensing

The development of multi-mode sensors for target detection has gained significant attention due to their enhanced accuracy and versatility. In this study, a fluorescent nanozymes composite (AuNC@CeMOF) was fabricated via self-assembly, combining orange-emitting gold nanoclusters (AuNC) with the cerium-based metal-organic framework (CeMOF) exhibiting intrinsic oxidase-like activity. Notably, the fluorescence properties of AuNC were significantly enhanced due to the confinement effect of CeMOF, improving sensor performance. Under optimized conditions, the dual-mode sensing platform, leveraging both the oxidase-mimicking activity and the enhanced fluorescence of AuNC@CeMOF, enabled the highly sensitive detection of tannic acid (TA). The sensor demonstrated a linear response range and an ultra-low detection limit, surpassing many conventional methods. Furthermore, the integration of smartphone-based analysis facilitated portable, on-site TA detection. This work highlights the feasibility of designing multifunctional nanozyme composites by synergizing fluorescence enhancement and enzyme-mimicking properties, offering a promising strategy for the discrimination and quantification of TA in complex samples.