Investigation of Genipin Cross-Linked Microcapsule for Oral Delivery of Live Bacterial Cells and Other Biotherapeutics: Preparation and In Vitro Analysis in Simulated Human Gastrointestinal Model

Table 1

Exposure of microcapsules to the simulated human GI transit (72 h in total) and the corresponding morphological changes.

Compartment	Stomach	Small intestine	Ascend. Colon	Transverse colon	Descend. Colon
in GI model	(V1𝑎)	(V2𝑎)	(V3𝑎)	(V4𝑎)	(V5𝑎)
pH	≤2	7.2–7.4	5.6–5.8	6.2–6.4	6.6–6.8
Exposure time (h)	2	4	18	24	24
Microcapsule morphology𝑏	Intact	Swelled, ~15% deformed	Collapsed	Collapsed or dissolved	Adhesive, ~30% ruptured
Microcapsule morphology𝑐	Intact	Slightly swelled,<1% burst	Spherical,<2% broken	Spherical intact	Spherical intact

𝑎Vessel (V) of bioreactors in the GI model representing the human GI tract.
𝑏Microcapsules cross-linked by genipin at 4^∘C.
𝑐Microcapsules cross-linked by genipin at RT.