A few years ago,melamine was found as contaminant in pet food sold in the U.S.and Canada and in milk,milk products,and infant formula,predominantly in China.Melamine has a number of industrial uses,but it is not approved for use in foods.In these incidents,however,melamine was illegally added to the foods.As there is an increasing public concern over food safety,selective detection methods for melamine in these products are highly desirable.Here,we report the design and evaluation of alternative fluorescence "turn-on" detection of melamine in solution and on membrane(Figure 1).