http://www.china.org.cn/china/Off_the_Wire/2023-03/21/content_85181903.htm

https://www.science.org/doi/10.1126/sciadv.ade0997

A team from Shanghai Jiao Tong University has created a calcium carbonate coating using electrostatic interactions that mimic the mineral formation of biological tissues. The ultra-resistant coating which disappears during gastrointestinal passage was shown to protect the probiotics organism Bacteroides fragilis during production from oxygen, UV and ethanol, and during GI passage from gastric and bile acids. The procedure was successfully used to treat colitis in a mouse model.

Graph from Science Advances citation