Sensitive turn-on fluorescent detection of melamine based on fluorescence resonance energy transfer

We here report a novel fluorescent method for the detection of melamine based on the high fluorescence quenching ability of gold nanoparticles. The fluorescence was significantly quenched via fluorescence resonance energy transfer when fluorescein molecules were attached to the surface of gold nanoparticles by electrostatic interaction. Upon addition of melamine, the fluorescence was enhanced due to the competitive adsorption of gold nanoparticles between melamine and fluorescein. Under the optimum conditions, the fluorescence enhancement efficiency [(I - I-0)/I-0] showed a linear relationship with the concentration of melamine in the range of 1.0 x 10(-7) mol L-1 similar to 4.0 x 10(-6) mol L-1, and the detection limit was calculated to be 1.0 x 10(-9) mol L-1. The proposed method showed several advantages such as high sensitivity, short analysis time, low cost and ease of operation.