A self-assembly hydrophobic oCDs/Ag nanoparticles SERS sensor for ultrasensitive melamine detection in milk

A simple, ultra-sensitive, and super-stable hydrophobic SERS platform for detection of melamine in milk is developed. The hydrophobic SERS platform was constructed via directly growing hydrophobic carbon/silver nanoparticles on glass by in-situ one-step carbonization using hexadecylpyridinium chloride monohydrate as stabilizer and reducing agent. The performances of SERS platform are systematically studied by using Rhodamine 6G (R6G) as a model, which achieves detection level of 10^-13 M and enhancement factor of 3.4 × 10¹⁰ for R6G detection with good uniformity and reproducibility, as well as 110 days stability in air. The FDTD simulation was used to confirm SERS enhancement mechanism. More importantly, SERS platform delivers good linear property in the range from 0.01 to 100 ppm, and low limit detection of 9 ppb for melamine detection in milk through direct drop on the platform. The SERS platform could have great applications in food safety, environmental monitoring, biomedicine and other fields.