Detection devices for the presence of molecules of interest (analytes) enjoyed a renewed burst with the introduction of biological components (biosensors). Their high specificity is often used in various fields, from environmental monitoring and biomedicine to the protection and promotion of agri-food products. However, the high cost of production and the lack of compatibility with mass sampling (high-throughput) sometimes limit their use. Our proposed biosensors are innovative for their ability to quickly change conformation in the presence of analytes, leading to a strong light emission easily measured by small and cheap optical detection devices. The simplicity of the selection of the highly specific biosensor for a desired analyte, the advantage of using it without any advanced skills, and the possibility of producing with low-cost technologies, put this new approach at the frontier for countless application fields.
The innovative element of these biosensors is the use of multi-domain proteins (chimeras): in the presence of the analyte in a few microliters of samples, the chimera undergoes rapid and reversible conformational changes, passing from a silent state (dark state) to a high-intensity fluorescence emission (bright state), and thus allowing for a very high signal-to-noise ratio. The device to be manufactured is low cost and consists of an integrated LED/laser light interrogation system, an assay area on paper for sample housing, and an integrated system of fluorescence collection optics, spectrally resolved, for coupling the light to a digital camera connected to a smartphone. Although chimeras can be suitably selected for every type of analyte (by in vitro molecular evolution techniques), one of the goals will be the development of biosensors for the specific detection of toxic molecules in the environment or in food production.