Closed-Loop Control of Substrate-Inhibited Reactions in Miniaturized Bioreactors

Abstract

Many molecular communication (MC) applications, such as miniaturized bioreactors, pursue functional goals beyond information transfer and require novel sensing and actuation schemes. MC offers a useful modeling and optimization framework for such systems, casting them as control problems in which desired outputs (e.g., substrate or product concentration) are specified and tracked. Here, we study the control of a miniaturized bioreactor running a substrate-inhibited enzymatic reaction. As excess substrate inhibits the enzyme, sustained release is preferable to batch addition. This release is achieved via an optically controlled, biologically realizable nanodevice. Since enzyme activity degrades over time, the required release rate changes and is adjusted using closed-loop feedback. Real-time substrate levels are measured by an RNA-based aptamer sensor with fluorescence response. Initial simulations indicate that this approach improves product yield in miniature bioreactors that are otherwise difficult to control.