UC Davis

Illicit production and consumption of fentanyl is a public health threat, and many counterfeit pills have been found to be laced with lethal doses of fentanyl. Rapid and accurate detection of fentanyl in unknown products or even aqueous samples can inform users of their exposure to the toxic chemical. The purpose of this research is to develop a rapid, sensitive, point-of-use sensor that can accurately detect and quantify the concentration of fentanyl and its main metabolite-norfentanyl in a consumer setting. Reticulated melamine foam (MF) possessing homogeneous macroporous framework structures were selected and utilized as a medium for incorporating colorimetric enzyme-linked immunosorbent assay (ELISA). When antibodies of fentanyl or the metabolite of fentanyl, norfentanyl, are immobilized onto the MF, the products could become unique biosensors for these two chemicals. This thesis presents chemical modifications of a commercially available MF using two different reagents, N, N’-disuccinimidyl carbonate (DSC) and cyanuric chloride (CC), and subsequent immobilization of two different antibodies to produce two sensitive and consistent biosensors of fentanyl and norfentanyl. A combination of chemically modified surfaces, a three dimensional (3D) macroporous framework structure, and immobilized fentanyl or norfentanyl antibodies onto the MF contributes to the unique performance of the biosensors, which can rapidly detect fentanyl and norfentanyl concentrations as low as 0.001-0.002 ppm without using any laboratory devices. The LOD of the fentanyl biosensor for the detection of fentanyl in 1XPBS solution and wastewater reached 0.005 ppm with the naked eye detection and 0.001 ppm with the use of a smartphone. The LOD of the norfentanyl biosensor for the detection of norfentanyl in the PBS buffer reached 0.001 ppm for the naked eye detection and the use of a smartphone. The fentanyl biosensor does not cross react with norfentanyl, but concentrations of fentanyl greater than 0.005 ppm have a high color intensity when using the norfentanyl biosensor. Although fentanyl cross reacts with the norfentanyl biosensor, the two sensors can be paired together as a presumptive and confirmatory test. These biosensors overcome the limitations of current techniques in detecting fentanyl and its derivative and are suitable for both laboratory and consumer uses.