Conductive metal–organic framework based label-free electrochemical detection of circulating tumor DNA

An ultrasensitive electrochemical biosensor was designed for the rapid label-free detection of circulating tumor DNA (ctDNA, EGFR 19 Dels for non-small cell lung cancer, NSCLC). We linked the highly conjugated tricatecholate, 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) with Ni(II) ions into the two-dimensional porous conductive metal–organic frameworks (MOFs), which is termed Ni-catecholates (Ni-CAT). Then, the AuNPs/Ni-catecholates/carbon black/polarized pencil graphite electrode (AuNPs/Ni-CAT/CB/PPGE) was obtained by electrodeposition of AuNPs on the surface of PPGE modified with Ni-CAT/CB composite materials. The AuNPs/Ni-CAT/CB/PPGE were used for label-less detection of ctDNA, with a total detection time of only 30 min. Under optimal detection conditions, the AuNPs/Ni-CAT/CB/PPGE sensor exhibited excellent detection performance with good linear response to ctDNA over a wide concentration range and the detection limit down to the femtomolar level. The sensor was applied to the determination of ctDNA in serum samples with high sensitivity. This simple, efficient, and expeditious method has practical value in liquid biopsy of ctDNA and has potential for development in early detection, treatment, and prognosis of tumors. Graphical abstract Herein, an ultrasensitive electrochemical biosensor was designed for the rapid label-free detection of ctDNA (EGFR 19 Dels for non-small cell lung cancer, NSCLC). We linked the highly conjugated tricatecholate, 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) with Ni(II) ions into the two-dimensional porous conductive metal–organic frameworks (MOFs), which is termed as Ni-catecholates (Ni-CAT). Then, the AuNPs/Ni-catecholates/carbon black/polarized pencil graphite electrode (AuNPs/Ni-CAT/CB/PPGE) was obtained by electrodeposition of AuNPs on the surface of PPGE modified with Ni-CAT/CB composite materials. The AuNPs/Ni-CAT/CB/PPGEs were used for label-less detection of ctDNA, with a total detection time of only 30 min. Under optimal detection conditions, the AuNPs/Ni-CAT/CB/PPGE sensor exhibited excellent detection performance with good linear response to ctDNA in the concentration range of 1 × 10 −15 M to 1 × 10 −6 M and with a detection limit as low as 0.32 fM. The sensor was applied for determination of ctDNA in serum samples and gave high sensitivity. This simple, efficient and expeditious method has practical value in liquid biopsy of ctDNA and has potential for development in early detection, treatment and prognos