Silver nanoparticles supported on magnetic iron oxide as fluorescence substrates for efficient detection of dyes

Currently, fluorescence detection has become a hot spot in the field of life science research. However, the fluorescence detection system faces some challenges arising from increased complex degree of detected substances, low sensitivity and difficult reusability of fluorescence substrates, as well easily being affected by external environment interference, causing that there is an urgent demand for developing new and sensitive fluorescence substrates. In this work, Fe3O4 nanoparticles were first prepared via a facile hydrothermal method and then silver-deposited Fe3O4 nanocomposites were fabricated. As a result, the significant fluorescent enhancement was realized for as-obtained Fe3O4/Ag as substrates, in which Ag nanoparticles played a vital role in surface enhanced fluorescence (SEF) effect mainly depending on their surface plasmon resonance to produce local electromagnetic enhancement. In addition, the liquid fluorescent substrate showed the stronger fluorescent signals in comparison with the solid fluorescent substrate that was subject to aggregation-caused quenching effect, which could be evaluated by the difference of enhancement factors for detecting Rhodamine B dyes which reached 42.9-fold and 12.5-fold, respectively, as well as by the difference of fluorescence stability for 10.0% and 35.9% intensity decay rate, respectively. Therefore, such composite materials will provide bright ideas and guides for particular applications in fluorescence detection.