Bio-inspired self-propelled diatom micromotor by catalytic decomposition of H₂O₂ under low fuel concentration

Abstract

Recently, active bubble-propelled micromotors have attracted great attention for fuel applications. However, for generating bubble-propelled micromotors, additional catalysts, such as Pt, Ag, and Ru, are required. These catalysts are expensive, toxic, and highly unstable for broad applications. To overcome these issues, in this study, we present an innovative methodology for the preparation of self-propelled motor machines using naturally occurring diatom frustules. This natural diatom motor shows effective motion in the presence of a very low concentration (0.8%) of H2O2 as a fuel at pH 7. Due to the unique 3D anisotropic shape of the diatom, the self-propelled motor exhibited unidirectional motion with a speed of 50 μm s-1 and followed pseudo first-order kinetics. It was found that a trace amount of iron oxide (Fe2O3) in the diatom was converted into Fe3O4, which can act as a catalyst to achieve the facile decomposition of H2O2. Interestingly, "braking" of the unidirectional motion was observed upon treatment with EDTA, which blocked the catalytically active site. These results illustrate that diatom catalytic micromotors have opened a new era in the field of catalysis and bioengineering applications.

Micro‐Bio‐Chemo‐Mechanical‐Systems: Micromotors, Microfluidics, and Nanozymes for Biomedical Applications

“…A growing body of literature has examined different shapes, sizes, materials of micromotors, [ 48 ] compositions, [ 31 ] and concentrations. [ 49 ] Mechanisms of catalytic reactions have been elucidated to achieve higher motive forces, ultra‐fast propulsion, [ 50 ] ultraprecise positioning, [ 51 ] develop accurate control methods, and test swarming/collective behaviors of micromotors. [ 52,53 ]…”

Ion-imprinted MnO2/CoFe2O4 Janus magnetic micromotors synthesized by a lotus pollen template for highly selective recognition and capture of Pb(ii) ions

“…They reveal promising prospects in pollutant detection, 13,14 pH monitoring, 15 adsorptive removal of pollutants, [16][17][18] accelerating pollutant degradation, 19,20 and killing bacteria. 21 Micromotors are mainly prepared by electrochemical templating, 22,23 droplet microfluidics, 24 Pickering emulsion, 25 copolymerization methods, 26 biological templating, [27][28][29] and evaporation. 30 However, the high performance of micromotors prepared by most of the methods requires additional chemical reagents or noble metals, which undoubtedly increases the preparation cost and brings environmental problems.…”

Self-assembly of cellular micro-bio machine parts

“…The glassy frustules are attractive in micro-bio robotics as they are rigid hollow bodies, ornamented with systematically arranged nanopores, which makes them ideal in a number of micro-bio robot applications. These might include but are not limited to; the development of self-propelled micro-motors [8], microscale biosensor platforms [9] and as drug delivery vehicles [10]. Panda et al [8] made use of diatoms with geometrical anisotropy to enable movement in a single direction under a low concentration of H 2 O 2 , which could then be terminated by EDTA addition.…”

“…These might include but are not limited to; the development of self-propelled micro-motors [8], microscale biosensor platforms [9] and as drug delivery vehicles [10]. Panda et al [8] made use of diatoms with geometrical anisotropy to enable movement in a single direction under a low concentration of H 2 O 2 , which could then be terminated by EDTA addition. Gale et al [9] functionalised Cyclotella frustules with model antibody rabbit immunoglobulin G (IgG) to amplify the intrinsic blue photoluminescence by a factor of six.…”