Smart hydrogel structure for microbiome sampling in gastrointestinal tract

Various microbiomes exist in the human body, however, there is an increasing research interest in the microbiomes present in the gastrointestinal (GI) tract and related diseases of the human body. In general, a healthy human body can maintain a certain balance in the microbiome of the GI tract. A condition, wherein the microbiome becomes imbalanced, is called "dysbiosis", and it can increase the probability of diseases in the body, especially in the GI tract. Therefore, various methods of sampling and analyzing the microbiomes have been proposed to diagnose dysbiosis. However, it is difficult to apply the existing methods to the various environments of the GI tract. To overcome this limitation, we propose a smart hydrogel structure for microbiome sampling in the GI tract. The proposed hydrogel structure comprises a core containing magnetic nanoparticles (MNPs) where microbiome sampling occurs and two protection layers (cellulose stearoyl esters (CSEs) and myristic acid (MA)) that protect the hydrogel structure from the external environment and allow sampling at the desired location. The hydrogel structure can be taken orally owing to its small size; and because it contains MNPs, it is possible to target and sample the microbiome at the desired location and retrieve the hydrogel structure after sampling via external magnetic actuation. The hydrogel structure is heated by an alternating magnetic field (AMF) so that the microbiome sampling can be actively initiated from the outside. The basic performance of the hydrogel structure was analyzed through various characterizations and fundamental tests. Further, the microbiome sampling tests using the hydrogel structure were performed in in-vitro and ex-vivo environments, and its microbiome sampling performances were verified through various analysis methods, such as scanning electron microscope (SEM), confocal, and 16 s rRNA sequencing. Consequently, the proposed hydrogel structure can be applied as a microbiome sampling device for the GI tract, which can be a useful method for diagnosing dysbiosis.