Electrochemiluminescent determination of CYFRA21-1 serum levels using Ti-Fe-O nanotubes immunoassay.

ABSTRACT

Prominent electrochemiluminescence (ECL) in Ti-Fe-O nanotube arrays (Ti-Fe-O NTs) with K2S2O8 as the cathode coreactant is reported for the first time. Compared with pure titanium dioxide nanotubes (TiO2 NTs), this heterojunction could effectively reduce the band gap, facilitate electronic transitions, and move the ECL potential to a positive direction. The ECL performance motivated the development of an ultrasensitive ECL immunosensor for detecting cytokeratin fragment 21-1 (CYFRA21-1). Magnetic beads loaded with conductive carbon black (CCB/MNTs) were used to efficiently quench the ECL signal of a Ti-Fe-O NTs electrode and were combined with an ECL immunoassay to realize sensitive detection of CYFRA21-1. Over a CYFRA21-1 concentration range of 1.0 pg·mL-1 ~ 100 ng·mL-1, the change in the ECL signal was highly linear with the logarithm of the CYFRA21-1 concentration, and the limit of detection (LOD) was 0.114 pg·mL-1. This ECL immunosensor was used to successfully determine the CYFRA21-1 content in serum. The recovery of CYFRA21-1 in actual serum was 88.6 - 104.4%, and the RSD was 1.4 - 3.0%. The coreaction solution used in this work was PBS (0.1 M, pH = 7.4) containing 0.05 M K2S2O8, the scanning range was -1.0 - 0 V, the photomultiplier tube (PMT) was set to 750 V, and the scanning rate was 100 mV·s-1.