Functionalized 3D H-SnS2-APTES-PTCA complexes with 3D hollow SnS2 as effective co-reaction accelerator for label-free electrochemiluminescence immunosensor

In this work, a novel, label-free, and self-enhanced electrochemiluminescence (ECL) immunosensor, based on 3,4,9,10-perylenetetracarboxylic acid (PTCA) and three dimensional hollow SnS2 (3D H-SnS2), was constructed to sensitively detect cardiac troponin I (cTnI). The 3D H-SnS2 was employed as an effective co-reaction accelerator in an ECL system, with the 3D H-SnS2 and PTCA cross-linked through (3-aminopropyl) triethoxysilane (APTES) to form a self-reinforcing ECL system. Functionalized 3D H-SnS2-APTES-PTCA complexes were then prepared and applied for the subsequent experiments. This system had plenty of active sites on the surface of insert-like SnS2 nanosheets within the 3D H-SnS2 and as such, it could strongly induce S2O82- to produce more SO4•- radicals. Furthermore, since the luminescent substance and the co-reaction accelerator were connected together, the distance between the SO4•- radicals and the luminescent PTCA could be effectively shortened, thus enabling SO4•- to act immediately on PTCA for significantly enhancing the ECL intensity. By analyzing the mechanism involved, it was found that the conversion between the ion pairs of Sn4+/2+ played a very important role in enhancing the signal. Based on the above work, the constructed biosensor was used to detect cTnI, a signaling molecule associated with acute myocardial infarction disease. And the sensor, with its linear response range of 16 fg mL−1-16 ng mL−1 and its low detection limit of 1.19 fg mL−1, displayed potential application value in the field of clinical analysis.