Major Urinary Proteins on Nanodiamond-Based Resonators Toward Artificial Olfaction

A new bio-sensing platform based on major uri- nary proteins (MUPs) from the mouse as chemical recognition elements has been developed. The transducers were surface acoustic devices coated with diamond nanoparticles as an inter- mediate layer enabling covalent attachment of the proteins. The resulting sensors detected 2,4-Dinitrotoluene, 4-Nitrotoluene, and 2-Isobutyl-3-methoxypyrazine at ppb levels. The best sensor showed a sensitivity of 24 000 Hz · ppm−1 to 2, 4-DNT when grafted with the protein MUP20. Trends in the sensitivity of the various VOC sensors were compared with the association constant values Ka of the proteins to target ligands measured by competitive assay in liquid phase. The system is able to detect analytes both in liquid as well as vapor phase and indicate that MUPs are robust bio-recognition elements that can be utilized in artificial olfaction applications.