High-Intensity Focused Ultrasound Combined with Ti₃C₂–TiO₂ to Enhance Electrochemiluminescence of Luminol for the Sensitive Detection of Polynucleotide Kinase

Luminol is a classic electrochemiluminescence (ECL) luminophore. The luminol–O 2 ECL system suffers from a problem, that is, the conversion rate of dissolved O 2 into reactive oxygen species (ROS) is low. In this work, we used high-intensity focused ultrasound (HIFU) pretreatment combined with Ti 3 C 2 –TiO 2 to construct a highly sensitive luminol–O 2 ECL system for the specific detection of polynucleotide kinase (PNK) first. On the one hand, HIFU generated ROS in situ as a coreactant via the cavitation effect to boost the luminol emission. On the other hand, Ti 3 C 2 –TiO 2 was prepared in situ via Ti 3 C 2 as a reducing agent, and it can aggregate and catalyze ROS generated in situ by HIFU. Moreover, the Ti on the Ti 3 C 2 –TiO 2 surface could bind to phosphate groups through chelation, thereby realizing highly specific detection of PNK. The sensor has a linear relationship range of 1.0 × 10 –5 to 10.0 U mL –1, and the limit of detection is 1.48 × 10 –7 U mL –1, which is superior to most existing methods. The sensor performance in HeLa cell lysate was measured with a satisfactory result. The designed ECL biosensor has potential applications in biological analysis and clinical diagnosis.