An amplified electrochemiluminescent aptasensor using Au nanoparticles capped by 3,4,9,10-perylene tetracarboxylic acid-thiosemicarbazide functionalized C60 nanocomposites as a signal enhancement tag

Abstract

A novel electrochemiluminescent (ECL) signal tag of Au nanoparticles capped by 3,4,9,10-perylene tetracarboxylic acid-thiosemicarbazide functionalized C₆₀ nanocomposites (AuNPs/TSC-PTC/C₆₀NPs) was developed for thrombin (TB) aptasensor construction based on the peroxydisulfate/oxygen (S₂O₈²⁻/O₂) system. For signal tag fabrication, the C₆₀ nanoparticles (C₆₀NPs) were prepared and then coated with 3,4,9,10-perylene tetracarboxylic acid (PTCA) by π–π stacking interactions. Afterwards, thiosemicarbazide (TSC) was linked with PTCA functionalized C₆₀NPs via amidation for further assembling Au nanoparticles (AuNPs). Finally, detection aptamer of thrombin (TBA 2) was labeled on the ECL signal amplification tag of AuNPs/TSC-PTC/C₆₀NPs. Herein, TSC, with the active groups of –NH₂ and –SH, was selected and introduced into the ECL S₂O₈²⁻/O₂ system for the first time, which could not only offer the active groups of –SH to absorb AuNPs for TBA 2 anchoring but also remarkably enhance the ECL signal of the S₂O₈²⁻/O₂ system by the formation of TSC-PTC/C₆₀NPs for signal amplification. Meanwhile, the sensing interface of a glassy carbon electrode (GCE) was modified by AuNPs/graphene (AuNPs/GR) nanocomposites with the large specific surface area and the active sites, followed by immobilization of thiol-terminated thrombin capture aptamer (TBA 1). With the formation of the sandwich-type structure of TBA 1, TB, and TBA 2 signal probes, a desirable enhanced ECL signal was measured in the testing buffer of an S₂O₈²⁻/O₂ solution for detecting TB. The aptasensor exhibited a good linear relationship for TB detection in the range of 1 × 10⁻⁵–10 nM with a detection limit of 3.3 fM.