The balance and diversity of microorganisms in the human gastrointestinal tract (GI) exert a strong influence on health in terms of drug metabolism, nutrition uptake and immune system function. Direct sampling of gut microbiome composition by conventional colonoscopy and gastroscopy techniques offers limited results. An orally administered capsule which can observe and sample the entire GI system offers a less expensive and complex diagnostic option.

The bacteria-sampling capsule was devised by researchers from Purdue University and Shenzhen MSU-BIT University (China) to go where no colonoscopy has gone before. The biocompatible, 3D-printed device safely (a) 3D drawing of device components. (b) Photograph of individual components. (c) Image of final assembled capsule. Source: Jose Fernando Waimin et al.captures and transports bacterial samples along the entire GI tract, from the mouth to the rectum.

When exposed to the pH of a certain gut location, the cap of the resin-based, pill-shaped device dissolves, exposing a hydrogel which expands and collects intestinal fluid containing bacteria. Expansion of the material resulting from liquid absorption exerts pressure to push a plug against the opening and seal the capsule. Following excretion of the noninvasive sampling device, the hydrogel is collected and analyzed to examine the bacteria present.

Results reported in RSC Advances confirm that a prototype capsule successfully sampled common gut bacteria in a culture solution designed to simulate GI flora , such as Escherichia coli, within an hour and effectively protected the cultures collected. The next steps will involve testing the devices in animal models and developing additional biodegradable coatings synthesized for sampling at specific target locations.