A smart capsule with a bacteria- and pH-triggered enteric polymer coating for targeted colonic microbiome sampling.

Abstract

The gut microbiome is recognized as a critical factor in advancing precision nutrition and medicine for health and in developing dietary recommendations and targeted therapies for gastrointestinal (GI) health and diseases. However, conventional sampling methods, such as fecal analysis and colonoscopy, often fail to capture microbial information from specific regions of the GI tract or require invasive procedures, thereby limiting accuracy and clinical utility. As a non-invasive alternative, passive sampling capsules have been developed for site-specific microbiome analysis by employing pH-sensitive enteric coatings that delay sampling until the capsule reaches the targeted intestinal region. Although this approach has been successful in the small intestine, colonic sampling remains challenging due to the high interpersonal variability in intestinal pH, which makes it difficult to rely solely on a pH-triggering mechanism. To overcome this challenge, a dual bacterially and pH triggered polymeric enteric coating was created by blending lactulose and N,N-dimethylaminoethyl methacrylate, enabling complete dissolution within the colonic region. Through systematic characterization of multiple polymer blend compositions using Fourier Transform Infrared Spectroscopy, Thermogravimetric Analysis, and Differential Scanning Calorimetry, an optimized design was identified that provides both suitable physical integrity and rapid (∼2 h) degradation in the presence of colonic bacteria, across a pH range of 5 to 8. The optimized blend was subsequently applied as a double-layer enteric coating on a sampling capsule, enabling the dissolution of the outer layer in the small intestine and complete dissolution of the inner layer in the colon. In-vitro and in-vivo pig model studies were conducted to validate the capsule's sampling performance and to ensure the preservation of the microbial environment. Furthermore, 16S rRNA sequencing revealed a taxonomic similarity between samples collected by the capsule and the colonic microbiome (residing between the ileum and fecal matter). Overall, this technology provides an effective approach to targeted microbial sampling and may pave the way for more comprehensive colonic microbiome analyses and improved diagnostic capabilities for GI diseases. STATEMENT OF SIGNIFICANCE: Precise monitoring of the gut microbiome is vital for understanding health and disease, yet current sampling techniques often lack precision or require invasive procedures. Our work introduces a novel, non-invasive capsule that targets the colon using a dual-trigger polymer system activated by both pH and colonic bacteria. This design enables localized sampling of gut microbiota, overcoming the limitations of fecal analysis, endoscopy, and earlier pH-triggered capsule designs. By capturing microbial communities directly from the colon, our technology provides deeper insights into colonic health and conditions such as inflammatory bowel disease and colorectal cancer. This breakthrough represents a significant advancement in precision nutrition and medicine for human health, and advanced diagnostics and targeted therapies to support dietary guidance, clinical practice and biomedical research.