The interfacial interactions of Tb-doped silica nanoparticles with surfactants and phospholipids revealed through the fluorescent response

The quenching effect of dyes (phenol red and bromothymol blue) on Tb(III)-centered luminescence enables to sense the aggregation of cationic and anionic surfactants near the silica surface of Tb-doped silica nanoparticles (SN) in aqueous solutions. The Tb-centered luminescence of non-decorated SNs is diminished by the inner filter effect of both dyes. The decoration of the silica surface by cationic surfactants induces the quenching through the energy transfer between silica coated Tb(III) complexes and dye anions inserted into surfactant aggregates. Thus the distribution of surfactants aggregates at the silica/water interface and in the bulk of solution greatly affects dynamic quenching efficiency. The displacement of dye anions from the interfacial surfactant adlayer by anionic surfactants and phospholipids is accompanied by the “off–on” switching of Tb(III)-centered luminescence.

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► Interfacial binding of dyes with Tb(III) doped SNs results in the luminescence quenching.
► Energy transfer from Tb(III) complexes to dyes is responsible for this quenching.
► Quenching effect of dyes probes into the aggregation of surfactants onto SNs.
► Cationic surfactant aggregation induces the quenching effect.
► Cationic–anionic surfactant aggregation induces the luminescent response of SNs.