A Fluorescence/Colorimetric Synergistic‐Enhanced Type‐I Heterostructured MOF@QDs for Both Multi‐Depth Food‐Freshness Prediction and Extra Preservation

Spoiled food has significantly impacted the global economy and public health, which increases worldwide concern about monitoring and preserving food freshness. Herein, a multi-functional type-I heterojunction (Eu@ZMC) is designed by europium metal-organic framework (EuMOF), zinc oxide quantum dots (ZnO QDs), and chlorogenic acid (CGA). Eu@ZMC achieves ratiometric fluorescent/colorimetric sensing of pH and biogenic amines to detect freshness. Besides, a paper-based platform (PEu@ZMC) is prepared and can detect histamine with the LOD of 0.0142 and 0.0136 µg mL^-1 in fluorescent and colorimetric modes, respectively. An advanced OR/NOT-gate logic device is further constructed to distinguish freshness into three levels (fresh, less fresh, and spoiled). This dual-mode sensor is synergistic-enhanced by the energy transfer triggered by ZnO QDs-promoted colorimetry and the type-I heterostructure of fluorescent EuMOF and ZnO QDs. The release of low-toxic zinc ions inhibits various bacterial growth, including Salmonella typhimurium. According to raw fish evaluation, Eu@ZMC not only effectively monitors spoilage externally and internally aligning with a commercial kit, but also reduces spoilage speed, which cannot be achieved through the classical detection strategy. This original work provides a simple, convenient, and reliable method for multi-depth and real-time visual food monitoring with extract freshness preservation, contributing to economic benefits and human health assurance.