Sensitive detection of melamine with silicon nanowire field effect transistor biosensor

Melamine, a widely used industry chemical, has been detected in pet foods and some protein-based food commodities, such as milk as a fraudulent substitute for protein since 2007. Melamine with concentrations higher than the safety limits can cause kidney injury. Therefore there is growing needs for a low cost portable sensor that can detect melamine in food. Here, we demonstrate two assay methods of using functionalized Si nanowire transistors (SiNW FETs) to detect melamine with high sensitivity. The direct detection using antibody coated SiNW FETs shows selective detection of melamine down to 50 ppb level (or 2 μM). Another competitive assay takes advantage of competition reaction between the BSASM2-antibody vs. melamine-antibody to indirectly detect the concentration of melamine selectively down to 20 pM level in buffer solutions. The results show that SiNW has the potential to become a portable low cost sensor for melamine detection.