title: Effect of chitosan coating on a bacteria-based alginate microrobot.
abstract: To develop an efficient bacteria-based microrobot, first, therapeutic bacteria should be encapsulated into microbeads using biodegradable and biocompatible materials; second, the releasing rate of the encapsulated bacteria for theragnostic function should be regulated; and finally, flagellated bacteria should be attached on the microbeads to ensure the motility of the microrobot. For the therapeutic bacteria encapsulation, an alginate can be a promising candidate as a biodegradable and biocompatible material. Owing to the non-regulated releasing rate of the encapsulated bacteria in alginate microbeads and the weak attachment of flagellated bacteria on the surface of alginate microbeads, however, the alginate microbeads cannot be used as effective cargo for a bacteria-based microrobot. In this paper, to enhance the stability of the bacteria encapsulation and the adhesion of flagellated bacteria in alginate microbeads, we performed a surface modification of alginate microbeads using chitosan coating. The bacteria-encapsulated alginate microbeads with 1% chitosan coating maintained their structural integrity up to 72 h, whereas the control alginate microbead group without chitosan coating showed severe degradations after 24 h. The chitosan coating in alginate microbeads shows the enhanced attachment of flagellated bacteria on the surface of alginate microbeads. The bacteria-actuated microrobot with the enhanced flagellated bacteria attachment could show approximately 4.2 times higher average velocities than the control bacteria-actuated microrobot without chitosan coating. Consequently, the surface modification using chitosan coating enhanced the structural stability and the motility of the bacteria-based alginate microrobots.
authors.affiliation: School of Mechanical Engineering, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju, 500-757, Republic of Korea.
authors.forename: Sung Jun
authors.initials: SJ
authors.lastname: Park
authors.forename: Yu Kyung
authors.initials: YK
authors.lastname: Lee
authors.forename: Sunghoon
authors.initials: S
authors.lastname: Cho
authors.forename: Saji
authors.initials: S
authors.lastname: Uthaman
authors.forename: In-Kyu
authors.initials: IK
authors.lastname: Park
authors.forename: Jung-Joon
authors.initials: JJ
authors.lastname: Min
authors.forename: Seong Young
authors.initials: SY
authors.lastname: Ko
authors.forename: Jong-Oh
authors.initials: JO
authors.lastname: Park
authors.forename: Sukho
authors.initials: S
authors.lastname: Park
mesh_terms: D000464:Alginates / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D018914:Cells, Immobilized / Q000378:metabolism*; D048271:Chitosan / Q000378:metabolism*; D020723:Glucuronic Acid / Q000378:metabolism; D006603:Hexuronic Acids / Q000378:metabolism; D008863:Microspheres
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D048271:Chitosan
keywords: Salmonella typhimurium; alginate; bacteria; chitosan; encapsulation; microbead; microrobot