Simultaneous Detection of Cu+ and Cu2+ Using Dual-functionalized Glass Micropipette Sensors

Copper ions (Cu + and Cu 2+ ) are vital for physiological functions, and their imbalance is implicated in disease progression. However, simultaneous detection of both species is challenging due to their similar properties. Here, we report a dual-functionalized glass micropipette sensor enabling independent detection of Cu + and Cu 2+ . UiO-66-NH 2 was grown in situ on the inner wall to capture Cu 2+ via amino coordination, reducing ionic current. Glutathione-functionalized carbon nanotubes (GCNTs) coated on the outer surface bind Cu + , increasing SERS signal via enhanced surface defects. The sensor exhibits a wide detection range (10 -1 –10 5 μM), a detection limit of 0.1 μM, and allows simultaneous monitoring of Cu + /Cu 2+ in the physiological range (2–10 μM). It further distinguishes copper ion levels in MCF-10A and MCF-7 cells, revealing altered copper homeostasis in cancer. This platform offers a sensitive, selective tool for studying copper in biological systems.