Rhodamine B-co-condensed spherical SBA-15 nanoparticles: facile co-condensation synthesis and excellent fluorescence features

Novel rhodamine B-co-condensed spherical SBA-15 nanoparticles (RhB-Cc-SBA-15NPs) and rhodamine B-post-grafted short columnar SBA-15 nanoparticles (RhB-Pg-SBA-15NPs) have been synthesized by a facile co-condensation approach and a relatively complicated post-grafting route, respectively. SEM, TEM, SAXRD, FTIR, absorption spectroscopy, fluorescence spectroscopy and nitrogen adsorption-desorption techniques were employed to characterize the morphology, the mesostructure and the spectral features of fluorescence nanocomposites with different doping amounts of RhB. The results show that (1) the facile co-condensation method involves an electron-donor acceptor (EDA) composite micelle, which plays two significant roles of uniformly dispersing RhB groups within the ordered mesopore channels and effectively adjusting the morphology and particle size of SBA-15 in the nano-scale; (2) novel spherical RhB-Cc-SBA-15NPs with a uniform particle size of ca. 400 nm have been obtained for the first time; (3) large numbers of RhB groups are covalently bound and monodisperse within the ordered mesoporous channels of the RhB-Cc-SBA-15NPs owing to the facile co-condensation method, however, most probably aggregated on the outside surface of the RhB-Pg-SBA-15NPs; (4) compared with other dye-doped silica materials reported previously, RhB-Cc-SBA-15NPs exhibit uniform size, high dispersivity and doping amounts of the bound RhB, high fluorescence quantum yields and fluorescence detectivity, and excellent photostability. RhB-Cc-SBA-15NPs, combining the advantages of a well-defined morphology and mesostructure, exhibit excellent fluorescence features, and present great potential for applications in drug delivery and fluorescence probing for medical diagnosis and synchronous therapy.