Ignition of photoluminescent intensity of quenched MoS2 quantum dots tetracycline mixture by levofloxacin via photoinduced electron transfer

A novel switchable signalling sensor based on molybdenum disulphide quantum dots (MoS2qds) have been developed as a fluorescent chemo sensor with high selectivity towards tetracycline (Tc) and levofloxacin (Levo). Tc upon interacting with MoS2qds forms a mixture which quenches the photoluminescent intensity of MoS2qds because of the dynamic quenching. A noteworthy increase in the fluorescence was observed when the MoS2qds-Tc mixture was complexed with Levo. This enhancement in the fluorescence is governed by a photoinduced electron transfer (PET) process in which the energy level ordering of the excited states is changed by the formation of complex of Levo with MoS2qds-Tc mixture due to the rotation of chromophore in Levo. The fluorescence recovery efficiency of Levo is 283%. The proposed sensor was used to analyse spiked samples of water, sewage and milk, the results found are in accordance with the experimental trend.