Ultra-sensitive and label-free detection of the measles virus using an N-heterocyclic carbene-based electrochemical biosensor.

Mayall, Robert M; Smith, Christene; Hyla, Alexander S; Lee, Dianne S; Crudden, Cathleen M; Birss, Viola Ingrid

With the current intense need for the rapid and accurate detection of viruses due to COVID-19 , we report on a platform technology that is very well suited for this purpose, using intact measles virus as a demonstration. Cases of infection due to the measles virus are rapidly increasing and yet current diagnostic tools used to monitor for the virus rely on slow (>1 hour) technologies. Here, we demonstrate the first biosensor capable of detecting the measles virus in minutes with no preprocessing steps. The key sensing element is an electrode coated with a self-assembled monolayer containing the measles antibody, immobilized through an N-heterocyclic carbene (NHC). The intact virus is detected by changes in resistance, giving a linear response to 10-100 µg/mL of the intact measles virus without the need to label or process the sample. The limit of detection is 6 µg/mL, which is at the lower limit of concentrations that can cause infections in primates. The NHC-based biosensors are shown to be superior to thiol-based systems, producing an approximately 10x larger response and significantly greater stability towards repeated measurements and long-term storage. This NHC-based biosensor thus represents an important development for both the rapid detection of the measles virus and as a platform technology for the detection of other biological targets of interest.