Electrochemical sensing interface based on the oriented self-assembly of histidine labeled peptides induced by Ni²⁺...

To construct an electrochemical sensing interface which was convenient for protease recognition and cleavage, we designed a strategy for directed self-assembly of histidine-tagged peptides on the electrode led by Ni²⁺ ions for electrochemical detection of prostate specific antigen (PSA). The electrode surface was first functionalized using carboxylated multiwalled carbon nanotubes and then modified with the metal ion chelating agent (5 S)-N-(5-Amino-1-carboxypentyl) iminodiacetic acid (NIA). After the Ni²⁺ was captured by NIA, the designed immune-functional peptide could be oriented assembly to the electrode interface through the imidazole ring of histidine at the tail, completing the construction of the recognition layer. Therefore, by adding the analyte PSA to identify and shear the immune-functional peptide, the ferrocene in its head was released, resulting in a reduction in the electrical signal, enabling sensitive detection. In addition, the self-assembly layer could be removed by pickling to realize the reconstruction of the recognition layer. Under optimal conditions, the electrochemical sensor had an ultralow detection limit of 11.8 fg mL^-1 for PSA, with a wide detection range from 1 pg mL^-1 to 100 ng mL^-1. In this work, an electrochemical sensing interface based on the histidine-tagged peptide induced by Ni²⁺ was formed to enable controllable oriented assembly on the electrode surface, and the recognition layer could be reconstructed via pickling, providing a potential approach for the design of repeatable interfaces.