Succinic acid functionalized silver nanoparticles (Suc-Ag NPs) for colorimetric sensing of melamine

Highlights: • A quantitative colorimetric sensing strategy is developed for the rapid, sensitive and selective determination of melamine. • The sensing system relies on the application of succinic acid as a selective recognition probe functionalised over Ag NPs. • The developed sensor system is simple and utilizes selective linkage for the recognition of melamine. • The assay provides a successfully route towards quantification of low-level melamine in complex matrix. In this study, a quantitative colorimetric sensing strategy is developed for the rapid, sensitive and selective determination of melamine. The sensing system relies on the application of succinic acid as a selective recognition probe functionalized over Ag NPs. The synthesized Ag NPs were modified with cysteamine to induce positively charged atmosphere which allowed easy and favorable functionalization of succinic acid. The di-carboxyl nature of succinic acid enabled its binding to both cysteamine and melamine. The strong and favorable linkage between succinic acids carbonyl and amine moieties of melamine triggered aggregation of silver NPs producing a significant shift in the measured absorption excitation. This change in the excitation along with the colorimetric response was found linearly proportional to the melamine concentration in the range of 0.1–1.2 μM. The developed sensor system is simple and unlike electrostatic attraction based sensor system utilize selective linkage for the recognition of melamine. In addition to this, the developed optical probe can efficiently be used for the determination of melamine in milk samples.