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 fluorescence resonance energy transfer (FRET)-based ratiometric nanosensor is reported for toxic Hg 2+ 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 Hg 2+ 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 Hg 2+ ions. The nanoparticle sensor can selectively detect Hg 2+ 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.