Immobilization of folic acid on Eu3+-doped nanoporous silica spheres

Folic acid (FA) was immobilized on Eu3+-doped nanoporous silica spheres (Eu:NPSs) through mediation of the 3-aminopropyltriethoxysilane adlayer. The ordered nanopores of Eu:NPS were preserved by the immobilization. The FA-immobilized Eu: NPSs showed the characteristic photoluminescence peak due to interactions between the FA molecules and Eu3+ ions, and highly dispersed stability in phosphate buffered saline.