Autonomous Temporal Control of Hydrogen Sulfide Delivery

Hydrogen sulfide (H₂S) is dichotomous in nature as it is lethal at higher concentrations, but at lower concentrations it shows a more cytoprotective nature. Due to its involvement in many physiological processes, it has recently risen to significance as a gasotransmitter alongside carbon monoxide (CO) and nitric oxide (NO). Experimentation using H₂S is thus important to generate in vitro and in vivo models for this ubiquitous gasotransmitter. However, laboratory studies involving H₂S are challenging due to the special handling conditions required to work with such a toxic gas. The use of chemical donors in the cell culture also show temporally varying release profiles, which are not optimal when trying to control H₂S in cell cultures lasting several days. Previously we applied microfluidics to deliver stable concentrations of H₂S, and in this work, we demonstrate a novel experimental method incorporating feedback control to precisely deliver H₂S that accounts for donor solution concentration decay.