It remains a significant challenge to study the interactions between metal ions and porphyrin molecules at single ion level. Here, we constructed a nanopore-based sensing for label-free and real-time analysis of the interaction between Cu²⁺ and 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin (TPPS). The results demonstrate that emerging electronic signatures of the Cu²⁺-TPPS complex that is completely different form the original free TPPS were observed in the α-hemolysin (α-HL) nanopore. Based on the distinctive electronic signal patterns between TPPS and Cu²⁺-TPPS complex, the unique nanopore sensor can achieve a highly sensitive detection of Cu²⁺ in aqueous media. The frequency of signature events showed a linear response toward the concentration of Cu²⁺ in the range of 0.03 µM – 1.0 μM, with a detection limit of 16 nM (S/N = 3). The sensing system also exhibited high selectivity against other metal ions, and the feasibility of this approach for practical applications was demonstrated with the determination of Cu²⁺ in running water.

在单离子水平上研究金属离子与卟啉分子之间的相互作用仍然是一项重大挑战。在这里，我们构建了一个基于纳米孔的传感技术，用于无标记和实时分析Cu ²⁺与5,10,15,20-四（4-磺基苯基）-卟啉（TPPS）之间的相互作用。结果表明，在α-溶血素（α-HL）纳米孔中观察到了与原始游离TPPS完全不同的Cu ²⁺ -TPPS络合物的新兴电子签名。基于TPPS和Cu ²⁺ -TPPS配合物之间独特的电子信号模式，独特的纳米孔传感器可以实现对Cu ²⁺的高灵敏度检测在水性介质中。签名事件的频率显示出对Cu ²⁺浓度在0.03 µM – 1.0 µM范围内的线性响应，检出限为16 nM（S / N = 3）。该传感系统还显示出对其他金属离子的高选择性，并且该方法在实际应用中的可行性通过测定自来水中的Cu ²⁺得以证明。