Validation of a Repurposed <i>p</i>H Monitoring Capsule for Cecal Applications Using Novel Synthetic Cecal Contents

Abstract This study presents a novel approach to monitoring pH changes in the cecum, a critical step toward understanding the dynamic interactions between the gut microbiota and probiotics. By repurposing the Bravo® capsule, originally designed for esophageal pH monitoring, we demonstrate its potential for accurate, continuous, and nonobstructive pH detection within a simulated cecal environment. To facilitate this investigation, we introduce the first synthetic cecal content (SCC) formulation. Our formulation closely mimics the mechanical properties of porcine cecal contents, particularly in terms of viscosity and shear response. This SCC recipe addresses a significant gap in the availability of simulated biological fluids for in vitro medical device testing. Rheometric analyses confirm the SCC's consistency with biological cecal contents, providing a cost-effective and efficient platform for preliminary device evaluations. Experimental results show that the Bravo® capsule can accurately detect pH changes within the SCC, closely matching readings from a handheld pH probe. The successful validation of the Bravo® capsule's performance in a simulated cecal environment, along with the development of a reliable SCC formulation, paves the way for future in vivo studies in porcine models. This research represents a significant advancement in the field of gut microbiome monitoring and holds promise for the development of targeted, microbiome-based therapeutics. By enabling real-tim/e, in situ analysis of the cecal microbiota's response to various interventions, this approach has the potential to revolutionize our understanding of the complex interplay between probiotics, diet, and gut health.