Entropy-driven strand displacement reaction for ultrasensitive detection of circulating tumor DNA based on upconversion and Fe3O4 nanocrystals

Early detection of cancer biomarkers applied in real-time disease diagnosis and therapies can increase the survival rate of patients. Circulating tumor DNA (ctDNA) as a typical cancer biomarker plays a great role in the process of tumor disease monitoring, especially in early diagnosis. Unfortunately, most ctDNA detection systems have not been widely used due to their low sensitivity, poor specificity, and high cost. Herein, we developed an alternative ctDNA detection system to present the levels of ctDNA by recording the fluorescence signals of the system containing upconversion nanoparticles (UCNPs), Fe3O4, and entropy-driven strand displacement reaction. The method has a practical sensitivity with a wide linear range from 100 amol L−1 to 1 nmol L−1 and a low detection limit of 1.6 amol L−1. Furthermore, the system demonstrates a practical application in mouse blood serum samples and meets the requirements for rapid, sensitive, specific, and economical diagnosis of cancers. Thus, this ctDNA detection system may have great potential for ctDNA detection and clinical diagnosis.