Conjugated polymer and spirolactam rhodamine-B derivative co-functionalized mesoporous silica nanoparticles as the scaffold for the FRET-based ratiometric sensing of mercury (II) ions

•A novel FRET-based ratiometric nanosensor for Hg2+ ions was successfully fabricated.•PPV and mercury-responsive recognition probe (SRhB) were co-encapsulated into MSNs.•PPV as energy donors exhibited steady fluorescent properties as compared with dye molecules.•Our strategy provided a useful method for constructing ratiometric sensing systems for analytes.

A novel fluorescence resonance energy transfer (FRET)-based ratiometric nanosensor is reported for toxic Hg2+ ions detection. Poly(p-phenylenevinylene) (PPV) chain was encapsulated into the pores of mesoporous silica nanoparticles (MSNs) by ion-exchange and in situ polymerization, and used as the energy-transfer donor. A spirolactam rhodamine-B derivative (SRhB), as an ion recognition element and energy-transfer acceptor, was embedded in the pores of MSNs to form PPV@MSN@SRhB as the nanosensor. The presence of Hg2+ in the dispersion solution of nanoparticles can induce the ring-opening reaction of the SRhB moieties and lead to the occurrence of FRET process, affording the nanoparticle system a ratiometric sensor for Hg2+ ions. The nanoparticle sensor can selectively detect Hg2+ ions with a detection limit of 200 nM (ca. 40 ppb). It has been found that the fabricated FRET-based scaffold with the conjugated polymer as a donor exhibited high environmental stability and was more preferred for the accurate ratiometric sensing. Moreover, the FRET-based ratiometric nanosensor can be applicable in a relatively wide pH range (pH = 5–8) in solution.

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