Rotibot: Use of Rotifers as Self‐Propelling Biohybrid Microcleaners

Abstract

Self-propelled biohybrid microrobots, employing marine rotifers as their engine, named "rotibot," are presented and their practical utility and advantages for environmental remediation are demonstrated. Functionalized microbeads are attached electrostatically within the rotifer mouth and aggregated inside their inner lip. The high fluid flow toward the mouth, generated by the strokes of rotifer cilia bands, forces an extremely efficient transport of the contaminated sample over the active surfaces of the functionalized microbeads. The reactive particles confined around the rotifer's lip are thus exposed to a high flow rate of the pollutant solution, resulting in dramatically accelerated decontamination processes, without external mixing or harmful fuels. Theoretical simulations, modeling the greatly enhanced fluid dynamic associated with such built-in mixing effect, correlate well with the experimental observations. The rotibot thus proves to be an effective, versatile, and robust dynamic microcleaning platform for removing diverse environmental pollutants. Microbeads functionalized with lysozyme and organophosphorus hydrolase enzymes are shown to be extremely useful for enzymatic biodegradation of Escherichia coli and the nerve agent methyl paraoxon, respectively, while ligand (meso-2,3-dimercaptosuccinic acid) modified beads are used for removing heavy metal contaminants. Rotifer-based biohybrid microrobots hold considerable promise as self-propelling dynamic pumps for diverse large-scale environmental remediation applications.

Multigear Bubble Propulsion of Transient Micromotors

“…A more detailed investigation of the effect of material selection upon multigear dynamics and discovering design principles for fine tuning the dynamics of multigear bubble propulsion micromotors will be the subject of our future studies. Our analysis of the fluid flow pattern around the microengines and its similarities to flow around filter feeder microorganisms suggest new possibilities aligned with our previous studies [33] for exploiting the transient micromotors for enhanced local mixing and environmental remediation. Our analysis framework provides a pragmatic guideline to quantitatively study the complex system of multigear bubble propulsion and investigate the effect of the material and environmental parameters (including additional parameters involved in other biological media such as serum or interstitial fluid) on elements of motion.…”

“…Figure 5 and Video S5 demonstrate the operation of a stationary and a motile Mg-TiO 2 microengine. The bubble ejection of a stationary microengine near a substrate induces a pattern of circular flow (Figure 5(a)) similar in shape but opposite in direction to a puller microorganism under confinement [33]. These filter feeder microorganisms mix their local environment by circular flow and bring food to their mouth.…”

Janus particles: from concepts to environmentally friendly materials and sustainable applications

“…Reproduced with permission from ref. [114]. Copyright 2019 WILEY-VCH Verlag GmbH & Co-KGaA, Weinheim platinum patch onto the rough surface of activated carbon microspheres allows the bubble propulsion of the Janus micromotors with high speeds of more than 500 μm s −1 along with high adsorption capacity of Pb 2+ [102].…”

“…Copyright 2019 WILEY-VCH Verlag GmbH & Co-KGaA, Weinheim platinum patch onto the rough surface of activated carbon microspheres allows the bubble propulsion of the Janus micromotors with high speeds of more than 500 μm s −1 along with high adsorption capacity of Pb 2+ [102]. In a following contribution from the same group, a different type of selfpropelled microrobots, employing marine rotifers, was presented [114]. These biohybrid so-called rotibots were fabricated via electrostatic adsorption of functionalized positively charged microbeads on the negatively charged surfaces of the rotifers' cilia ( Fig.…”

“…These biohybrid so-called rotibots were fabricated via electrostatic adsorption of functionalized positively charged microbeads on the negatively charged surfaces of the rotifers' cilia ( Fig. 11a) [114]. The high fluid flow towards the mouth led to a very efficient transport of contaminated water to the functionalized microbeads [114].…”