Synthesis and characterization of [Eu(DBM)3phen]Cl3 @ SiO2-NH2 composite nanoparticles

Fluorescent rare earth complex Eu(DBM)3(phen)]Cl3@SiO2-NH2 nanoparticles were synthesized by combination of solvent precipitation method and Stöber method. The morphologies, structure, surface and optical properties of the samples were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and fluorescence spectrophotometer (FS). The observation from FE-SEM images indicate that the obtained samples are spherical and uniform nanoparticles with a tunable average sizes from 140 nm to 300 nm. TEM results verify a core-shell structure of the nanoparticles. The FTIR spectrum confirms the characteristic vibration absorption peaks of the complex [Eu(DBM)3(phen)]Cl3@SiO2-NH2. TGA result indicates that the complex is stable below 200 degrees C. The photoluminescence analysis shows that the complex has Eu3+ characteristic red luminescence and broader excitation peak from 200 nm to 450 nm that can meet the demands of fluorescent confocal imaging. The amino groups are directly introduced to the [Eu(DBM)3(phen)]Cl3@SiO2-NH2 nanoparticles surface by using APS (3-aminopropyl triethoxysilane). This makes the surface modification and bioconjugation of the nanoparticles easier. The nano-sized spheres could be provided a basis for further expansion of its application in biomedical imaging, biological detection and fluorescent nanoprobes.