Metal–organic frameworks-based biosensor for sequence-specific recognition of double-stranded DNA

Abstract

A simple, cost-efficient, sensitive and selective fluorescence sensor is developed for sequence-specific recognition of duplex DNA (ds-DNA) in vitro using metal–organic framework (MOF) as the sensing platform. N,N-Bis(2-hydroxy-ethyl)dithiooxamidatocopper(II) (H₂dtoaCu) was chosen as the example MOF, because it strongly chemisorbs the dye-labeled probe TFO (triplex-forming oligonucleotide), and quenches fluorescence from the dye. In the presence of target ds-DNA (the PPT of HIV RNA, a 16-bp ds-DNA sequence), the TFO could interact with the major groove in ds-DNA (via Hoogsteen hydrogen bonding) to form a rigid triplex structure, resulting in fluorescence recovery. The enhanced fluorescence signal has a relationship with the ds-DNA concentration, the detection limit is as low as 1.3 nmol L⁻¹ (S/N = 3) with good selectivity, which is lower than that based on a graphene oxide platform and electrochemical-DNA sensor.