C. elegans based microfluidic lab-on-chip platform for high-throughput detection of cancer metabolites in urine.
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VI - Fisica applicata, acceleratori e beni culturali
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This work exploits microfluidics to perform high-throughput neuronal calcium imaging $in vivo$ in response to precise chemical stimulation patterns. More specifically, we developed a multi-physics platform to record neuronal activity from sensory neurons in a population of $C. elegans$ in response to cancer metabolites in urine samples. The project relies on the exceptional sense of smell of the nematodes, enabling them to discriminate healthy urine from urine of cancer patients. $C. elegans$ displays strong attraction towards human cancer cell secretions and urine, while control samples induce avoidance behavior. This reflects on different neuronal activity patterns. After performing experiments both on behavior and neuronal activity of nematodes in the presence of healthy and cancer urine, we developed a prototypical setup merging behavioral and neuronal analysis. Our solution is a multi-layer architecture incorporating a microfluidic chip on a calcium imaging system able to simultaneously monitor the neuronal activities of olfactory neurons (expressing GCaMP) and chemotactic behavior, tracking all animals inside the chip. This allows to determine whether neurons detect cancer metabolites and how this ability affects behavioral outcomes. The high spatial and temporal control of the environmental stimuli is ensured by a previously designed microfluidic structure comprising a main chamber for calcium imaging and channel branchings, providing flow uniformity inside the chip. A system of electrovalves and micropumps controls the delivery of different urines and buffer solutions. We tested several samples finding an extremely accurate discriminating power with respect to chemotactic assays. We quantify the nematode response by introducing a neuron activity index measuring the averaged fluorescence over all tested animals both for controls and cancer samples, obtaining high values of accuracy.