A Microphysiometric System Based on LAPS for Real-Time Monitoring of Microbial Metabolism

Abstract

Macronutrients (carbohydrates, fat and protein) are the cornerstones of daily diet, among which carbohydrates provide energy for the muscles and central nervous system during movement and exercise. The breakdown of carbohydrates starts in the oral cavity, where they are primarily hydrolyzed to glucose and then metabolized to organic acids. The end products may have an impact on the oral microenvironment, so it is necessary to monitor the process of microbial metabolism and to measure the pH change. Although a pH meter has been widely used, it is limited by its sensitivity. We then introduce a light addressable potentiometric sensor (LAPS), which has been used in extracellular acidification detection of living cells with the advantages of being objective, quantitative and highly sensitive. However, it is difficult to use in monitoring bacterial metabolism because bacteria cannot be immobilization on the LAPS chip as easily as living cells. Therefore, a microphysiometric system integrated with Transwell insert and microfluidic LAPS chip was designed and constructed to solve this problem. The decrease in pH caused by glucose fermentation in Lactobacillus rhamnosus was successfully measured by this device. This proves the feasibility of the system for metabolism detection of non-adhere targets such as microorganisms and even 3D cells and organoids.