A portable multi-channel sensing device using Au nano-urchins as probes for melamine detection in milk

Facile detection of melamine in milk was realized through a portable multi-channel sensing device using Au nanoparticles with urchin-like structures as sensing probes. The detection mechanism was based on the aggregation of Au nano-urchins, induced by the formation of Au–N bonding with melamine. The Au nano-urchins were synthesized by a seed-mediated growth method in the presence of hydroquinone, which has the localized surface plasmon absorption at about 680 nm. The results showed that the melamine detection was environment pH dependent. The optimal melamine detection condition occurred when the pH of the BR buffer was 5.72. A better selectivity to melamine was fulfilled when compared with its structurally similar compounds: cytosine, uracil, and thymine. The multi-channel sensing device has a detection limit of 18 nM for melamine in milk, which could meet the requirement for monitoring the melamine amount in milk.