Dual-mode amplified fluorescence oligosensor mediated MOF-MoS2 for ultra-sensitive simultaneous detection of 17β -estradiol and chloramphenicol through catalytic target- recycling activity of exonuclease I

Abstract

The research outlines a novel ultrasensitive oligosensor which was designed by FRET-based selective simultaneous detection of multiple organic pollutant (chloramphenicol (CP) and 17β-estradiol (17E)) utilizing the MOF-MoS2 nanomaterial with Exo I signal amplification and target recycling strategy. In this oligosensor, the specific oligomers of 17E (ROX-SSO) and CP (TAMRA-SSO) are used as the recognition parts and the ROX and TAMRA as the fluorescent probes. The cubic-MOF incorporated by a few layered MoS2 sheets (MOF-MoS2) is used as oligomer adsorbing material and an efficient fluorescent nanoquencher for reducing the background signal. In this detection approach, the ROX-SSO and TAMRA-SSO probes could be adsorbed on the surface of the MOF-MoS2 through π-stacking and Vander Waals interactions. At the same time, the fluorescence of the ROX and TAMRA could be efficiently quenched due to the energy transfer between fluorophores and MOF-MoS2. In the addition of 17E & CP, the specific oligomers can be preferentially bound with the 17E & CP, and the newly formed ROX-SSO-17E &TAMRA-SSO-CP complex can be released from the MOF-MoS2 surface and the partial recovery of fluorescence signal. Subsequently, the addition of Exo I is to trigger and digest the ROX-SSO-17E &TAMRA-SSO-CP complex, resulted in the remarkable recovery of fluorescence emission. At the same time, the liberated targets mediate a new cycle of digestion, resulting in the ultra-trace detection of targets. Thus, with the aid of the helper MOF-MoS2 the turn-on detection of 17E and CP may be easily accomplished by observing the fluorescence signal of the respective fluorophores from “off” to “on”. Under optimal circumstances, the oligosensor has an excellent accuracy of 17E and CP, with detection limits of 180 and 200 pM, respectively. Furthermore, for the first time, the research successfully utilized this oligosensor to detect 17E and CP in milk, honey and water samples.