Continuous pH monitoring in organ-on-chip devices with single-step fabricated DNA scaffold sensors conjugated hydrogels and machine learning

In recent years, novel technologies in microfabrication and bioengineering, such as Lab-on-Chip and Organ-on-Chip, have greatly transformed the research approach to studying complex biological mechanisms. Thanks to these innovations, many up-to-date platforms allow scientists to track different chemical quantities and biological molecules in a small, biological-like environment. However, many of these systems often have difficulty monitoring such molecules in real-time, losing the real dynamics of the experiment. Crucial information also resides in the spatial distribution of the chemical quantity, which can be correlated with the biological phenomenon. For this reason, this work explores a new approach to integrating DNA-scaffold hydrogels into Lab-on-Chips. Using a stereolithographic technique, different DNA-conjugated fluorescent hydrogel sensors are precisely localized into the device, using geometrical shapes to distinguish them. A machine-learning algorithm is trained to perform real-time data analysis by recognizing different hydrogels during time-lapse experiments, extracting their local optical response to chemical stimuli. This technique is finally validated in real-time spatiotemporal pH monitoring. The kinetics of two enzymes (urease and acetylcholinesterase) and embryoid bodies’ metabolism in a Lab-on-Chip environment are monitored in real-time, demonstrating the high spatiotemporal resolution and accuracy of the proposed technique.