Red-Emissive Copper–Gold Bimetallic Metal–Organic Gel Nanozyme as a Highly Sensitive and Selective Ratiometric Photoluminescent Probe for Cellular Thiamine Detection

). The biosensor demonstrated two linear ranges (0.005-0.5 μM and 0.5-40 μM), a detection limit of 1.58 nM, high selectivity over phosphorylated thiamine derivatives, and high stability. Its practical utility was validated by accurately quantifying thiamine levels in different cell lines (RSC96, HeLa, and MCF-7), showing good agreement with a reference high-performance liquid chromatography method. This work not only establishes a reliable tool for cellular thiamine bioanalysis, but also showcases the potential of heterometallic MOGs as versatile multifunctional biosensing platforms.