Motility analysis of bacteria-based microrobot (bacteriobot) using chemical gradient microchamber

• Published in: Biotechnology and bioengineering Vol. 111; no. 1; pp. 134 - 143
• Main Authors: Park, Daechul, Park, Sung Jun, Cho, Sunghoon, Lee, Yeonkyung, Lee, Yu Kyung, Min, Jung-Joon, Park, Bang Ju, Ko, Seong Young, Park, Jong-Oh, Park, Sukho
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.01.2014; Wiley Subscription Services, Inc
• Subjects: Bacteria; bacteriobot; Biotechnology; Biotechnology - instrumentation; Biotechnology - methods; Chemicals; Chemotactic Factors - pharmacology; chemotaxis; Chemotaxis - drug effects; Chemotaxis - physiology; Drug Delivery Systems; microchamber; Microfluidic Analytical Techniques - instrumentation; microrobot; Robotics - instrumentation; Salmonella; Salmonella typhimurium; Salmonella typhimurium - physiology; Tumors; microrobot; microchamber; bacteriobot; Salmonella typhimurium; chemotaxis
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.25007

ABSTRACT A bacteria‐based microrobot (bacteriobot) was proposed and investigated as a new type of active drug delivery system because of its useful advantages, such as active tumor targeting, bacteria‐mediated tumor diagnosis, and therapy. In this study, we fabricated a bacteriobot with enhanced motility by selective attachment of flagellar bacteria (Salmonella typhimurium). Through selective bovine serum albumin (BSA) pattering on hydrophobic polystyrene (PS) microbeads, many S. typhimurium could be selectively attached only on the unpatterned surface of PS microbead. For the evaluation of the chemotactic motility of the bacteriobot, we developed a microfluidic chamber which can generate a stable concentration gradient of bacterial chemotactic chemicals. Prior to the evaluation of the bacteriobot, we first evaluated the directional chemotactic motility of S. typhimurium using the proposed microfluidic chamber, which contained a bacterial chemo‐attractant (L‐aspartic acid) and a chemo‐repellent (NiSO4), respectively. Compared to density of the control group in the microfluidic chamber without any chemical gradient, S. typhimurium increased by about 16% in the L‐aspartic acid gradient region and decreased by about 22% in the NiSO4 gradient region. Second, we evaluated the bacteriobot's directional motility by using this microfluidic chamber. The chemotactic directional motility of the bacteriobot increased by 14% and decreased by 13% in the concentration gradients of L‐aspartic acid and NiSO4, respectively. These results confirm that the bacteriobot with selectively patterned S. typhimurium shows chemotaxis motility very similar to that of S. typhimurium. Moreover, the directional motilities of the bacteria and bacteriobot could be demonstrated quantitatively through the proposed microfluidic chamber. Biotechnol. Bioeng. 2014;111: 134–143. © 2013 Wiley Periodicals, Inc. Actual 3D reconstruction image of bacteria‐based microrobot (bacteriobot) and schematic representation of gradient‐generating microfluidic chamber for evaluation of bacteriobot chemotaxis. Fluorescent microscopic images of bacteriobot distribution at each point in chemotactic microfluidic chamber: PBS vs. PBS, PBS vs. L‐aspartic acid, and PBS vs. NiSO4. The bacteriobots showed positive chemotaxis toward the chemo‐attractant gradient and negative chemotaxis against the chemo‐repellent.