A unique supramolecular assembly between sulfated cyclodextrin, silver and melamine: Towards a fluorescence based dual wavelength detection approach for melamine

Nitrogen-rich melamine has been often used by fraudulent merchants as an adulterant to food and dairy products which exhibit toxic effects, leading to life-threatening diseases. This has triggered enormous activity on developing methods for the recognition of melamine in various food items for protecting public health and food safety. In recent times, fluorescence methods have emerged as powerful analytical tools for sensor development. The previously reported fluorescence-based methods for melamine detection, either require tedious synthesis procedures or operate through single wavelength-based signal output, making their accuracy susceptible to minute changes in the experimental environment. Herein, to overcome these limitations, we report the recognition of melamine which is achieved through the formation of a serendipitously discovered unique supramolecular assembly. The assembly consists of sulfated cyclodextrin, silver ion and melamine which, in turn, encapsulates a molecular rotor dye, Thioflavin-T, to yield a fluorescence turn-on response towards melamine. Importantly, the supramolecular assembly is responsive at dual wavelengths and is builtup with all commercially available economical molecules. Overall, the present system offers a simple, sensitive, label-free and highly selective detection for melamine. Importantly, the melamine containing supramolecular ensemble is also found to perform in commercial milk sample promising its future application prospect.