Principle of Operation
Cellock Holmes is devised based upon a SynBio approach comprised of a two-dimensional biosensor and a measurement device. The two-dimensional biosensor is designed to recognize quorum sensing molecules secreted by the pathogen cells and to generate a distinct fluorescence signal, while the measurement device is designed to recognize and analyse the produced signal. To overcome the limitation of our REACh construct to bacteria that secrete autoinducers, we developed an alternative detection method (Galectin-3 construct), which is based on tagging cells with a fluorescent reporter.
[graph quorum senising]
Our sensor cells are immobilized in agar chips. To make the chips, we mix the sensing cells, also known as Cellocks, with liquid LB agar.
In the course of our project, we designed a casting mold specifically for the production of our agar chips. When the agar has cooled down, the chips are cut out of the mold and are ready to use. Storage of the readily usable sensor chips is possible for 2 days at 4 °C when using LB medium or for 5 days if TB-medium is used. If you want to know exactly how our chips are manufactures, you can read up on more details in our Protocols section.
The application of Cellock Holmes for detection of P. aeruginosa cells is simple: fist, a sampling chip is placed on a hard surface that is potentially contaminated with the pathogen. Second, the chip is put onto one of our sensor chips. Subsequently, the two layered chip-stack is then put into a petri dish, which is inserted into our measurement device WatsOn for evalutation.
introduced where it is incubated at 37 °C.
After a short time, the chip is illuminated with blue light. WatsOn takes a picture of the chip and the software Measurarty analyzes any fluorescent signal. Depending on the intensity of the signal and the size of the spot, Cellock Holmes can calculate concentration and distribution of P. aeruginosa on the sampled surface.
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