Biosensor research from Kai Johnsson’s laboratory at Ecole Polytechnique Fédérale de Lausanne (EPFL) gave way to the startup, LUCENTIX, which created a biosensor that enables patients to easily track drug concentrations in their blood without the need for complex lab systems.
The biosensor is a molecule made up of three components: a protein that can bind the drug to be monitored; the light-producing enzyme luciferase; and a “tagging” molecule called SNAP-tag, which carries a fluorescent ligand that the protein recognizes and binds when no drug is present. This causes a reaction between the luciferase and the fluorescent molecule—bioluminescent resonance energy transfer (BRET)—which produces a red light.
The process involves replacing the binding protein of the biosensor with part of an antibody that has been developed against the target drug. When the biosensor detects and binds the drug in the patient’s blood or saliva, the antibody binds this rather than the SNAP-tag’s fluorescent ligand. As the ligand is displaced, the BRET reaction is progressively disrupted, and emits a blue light.
The EPFL scientists successfully tested the new biosensors against three drugs—methotrexate, theophylline, and quinine—in the laboratory. The next step will be to optimize the biosensor’s sensitivity so that it can accurately detect nanomolar or even lower concentrations of drugs/biomolecules in clinical samples.