Highly selective electrochemical strategy for monitoring of cerebral Cu²⁺ based on a carbon dot-TPEA hybridized surface

Direct determination of cerebral metal ions in small volume biological samples is still the bottleneck for evaluating the roles that metal ions play in the physiological and pathological processes. In this work, selected copper ion (Cu²⁺) as a model, a facile and direct electrochemical method for detection of Cu²⁺ has been developed on the basis of two new designed strategies: one is specific recognition molecule for Cu²⁺-AE-TPEA (N-(2-aminoethyl)-N,N′,N′-tris(pyridine-2-yl-methyl)ethane-1, 2-diamine); another is carbon dots (C-Dots) with high electrocatalytic activity. Based on the high affinity between TPEA and Cu²⁺, the electrode assembled with C-Dot-TPEA hybridized nanocomposites shows high selectivity toward Cu²⁺ over other metal ions, amino acids, and biological coexisting species, such as uric acid (UA), ascorbic acid (AA), and so on, which makes it possible to be used for determination of Cu²⁺ in the complex brain system. By taking advantage of C-Dots, a dynamic linear range from 1 μM to 60 μM is first achieved with a detection limit of ∼100 nM in aCSF solution. In addition, the developed method with theoretical simplicity and less instrumental demands exhibits long-term stability and good reproducibility. As a result, the present strategy has been successfully applied in detection of cerebral Cu²⁺ in normal rat brain and that followed by global cerebral ischemia, combined with in vivo microdialysis. The determined concentrations of Cu²⁺ in the rat brain microdialysates by the present method are found to be identical to those obtained by the conventional ICP-AES method.