Enriched encapsulation and fluorescence enhancement of europium complexes in microcapsules

Microcapsules with an average diameter of 3.3 µm are obtained through the layer-by-layer (LbL) self-assembly technique by using MnCO3 microparticles with voids and pores as the template core. MnCO3 enriches the electrically neutral europium complex Eu(DBM)3Phen (DBM = dibenzoylmethane, Phen = 1,10-phenanthroline) both in the shell and inside the microcapsules. About 6 times more intense fluorescence emission is thus observed for microcapsules from MnCO3 compared to those obtained from a melamine formaldehyde (MF) core. The microcapsules exhibit two characteristic fluorescence peaks of the europium complexes at 596 and 612 nm, the latter sharp peak encompasses high monochromaticity. The assembly of fluorescence-enhanced microcapsules with Eu(DBM)3Phen show a new concept to enrich functional molecules by the LbL technique and has application potential in simultaneous multicolor bioassays.