Colorimetric sensor based on dual-functional gold nanoparticles: analyte-recognition and peroxidase-like activity.

A novel colorimetric sensor based on the interaction ability with specific analytes and peroxidase-like activity of gold nanoparticles was established in this work. Combining the high-affinity binding between bare gold nanoparticles and melamine with signal amplification procedure based on the catalytic activity of gold nanoparticles for oxidation of TMB, melamine with the concentration as low as 0.02 mg/L can be easily distinguished by naked-eye observation. Such system can be adapted through carefully-controlled surface modifications of gold nanoparticles for determination of other targets.