Unique Organic–InorganicHybrid Copper(I) Phosphatewith Ultralow Ractopamine Detection Limit and In Situ Sensing Ability

We successfully synthesized and characterized the first-ever organic–inorganic hybrid metal phosphate, <b>NTOU-10</b>, featuring lower-valence copper nodes under hydrothermal conditions. The crystalline structure, confirmed through single-crystal X-ray diffraction, thermogravimetric analysis, solid-state NMR spectroscopy, X-ray photoelectron spectroscopy, and bond valence-sum calculations, revealed its chemical composition, and unique coordination bonding models between organic linkers, metal nodes, and phosphate groups. These building blocks intricately bonded through metal–oxygen and metal–nitrogen linkages to form a highly complex crystalline structure. Taking innovation a step further, we polymerized <b>NTOU-10</b> with pyrrole to develop the hybrid <b>NTOU-10@polypyrrole</b> (PPy) electrode, setting a groundbreaking record with an ultrasensitive limit of detection (LOD) of 3.31 × 10^–19 M for ractopamine (RAC) sensing, surpassing existing crystalline materials by more than 9 orders of magnitude. The real-world effectiveness of this biosensor was demonstrated by detecting RAC in spiked pork samples. Additionally, we integrated the <b>NTOU-10@PPy</b> electrode into a flow injection analysis (FIA) system, offering advantages such as rapid detection, minimal sample requirement, and operational convenience. This work presents a significant leap forward in the design and synthesis of novel materials, along with the development of a high-performance biosensing platform for RAC detection.