Phosphate Anions Promote the Electromigration of Charge-Inversed TPE[14]aneN4 in a Homogeneous Electrochemiluminescence System for Kanamycin Detection

Abstract Homogeneous electrochemiluminescence (ECL) assay has emerged as a research hotspot due to its facile operation and high stability. Among the reported homogeneous ECL systems so far, the intensity of ECL signals is mainly regulated by changing the migration rate of luminophores toward the electrode, while the influence of ions in the base solution on signal intensity is rarely taken into consideration. In this study, a positively charged amphiphilic TPE[14]aneN4 was synthesized to explore the effect of its interaction with phosphate anions on ECL signal intensity. TPE[14]aneN4 can self-assemble into spheres, and the quaternary ammonium cationic groups (–NR4+) on the surface can interact with phosphate anions to achieve charge inversion. After positive voltage is applied, these particles can migrate toward electrodes more rapidly and generate intense ECL signals. Thus, to achieve sensitive detection, an “off–on” ECL bioassay was constructed based on TPE[14]aneN4 as emitters by combing host–guest interaction. After TPE[14]aneN4 is loaded into the γ-cyclodextrin (γ-CD), it remains in a dispersed state and interacts weakly with phosphate anions, resulting in weak ECL signals. When the kanamycin (Kana) is added, the released S1–Au-α-Amylase can cleave γ-CD, prompting TPE[14]aneN4 to reaggregate into spheres with phosphate anions and S1–Au-α-Amylase on the surface and boosting the ECL signal intensity. The sensor exhibits a linear relationship between ECL intensity and concentration within the range of 1.0 × 10–10 M to 1.0 × 10–5 M, with a 9.56 pM limit of detection, achieving sensitive detection of Kana. And the detection results are highly consistent with those of standard methods, demonstrating excellent application value.