Visible-Light-Driven Asymmetric TiO₂-Based Photocatalytic Micromotor Hybridized with a Conjugated Polyelectrolyte and Glucose Oxidase

Abstract

We fabricated a TiO2-based micromotor that was asymmetrically decorated with a water-soluble conjugated polymer (WSP) on one hemisphere and glucose oxidase (GO x ) on the opposite hemisphere. The WSP, which had photocatalytic activity for H2O2 decomposition, enabled motion of the micromotor under visible light. The GO x on the other hemisphere of the micromotor decomposed glucose to produce H2O2 and enabled motion of the micromotor without light irradiation. In addition, WSP and GO x were attached to TiO2 by chemical bonds, providing stability during use. As a result, the micromotor could move by self-generating H2O2 for its own fuel by consuming glucose even without photoirradiation. The micromotor could move faster than without visible light irradiation through the synergistic decomposition of glucose and H2O2 under visible light by the diffusiophoretic mechanism with a speed of 7.49 μm/s.

Enzyme-powered micro- and nano-motors: key parameters for an application-oriented design

“…3C). It is mostly used on silica by the Sánchez group, which can offer a spontaneous patch distribution which breaks the symmetry 89 and drives propulsion, 34,46,60,[71][72][73]75,76,78,[80][81][82][83][84]87,93,96,111,113,117 although it has also been applied to build Janus structures 68,70,99,100,131 and tubular motors. 86 The main concern with this method is that (1) because of the two carboxylic groups of glutaraldehyde, there is a tendency to crosslinking and aggregation and (2) given the high quantity of amino groups on enzyme macromolecules, there is no ne control of the orientation of enzymes, which can affect both catalysis and active motion.…”

“…4D) to power motion consuming glucose and producing gluconic acid and H 2 O 2 . 67,68,70 This enzyme's biocompatibility and substrate bioavailability have made it gain interest for biomedical applications, 37,62 especially recently to power drug delivery systems against breast cancer. 111 However, the turnover rate of glucose oxidase is rather slow, and the mechanism of action has been understudied.…”

“…63 Metals have also been used as a layer within the structure of (poly(3,4-ethylenedioxythiophene)), poly(sodium styrene sulfonate) (PSS-PEDOT-Au), 64 within polystyrene with poly(diallyldimethylammonium chloride), poly(styrene sulfonate) and poly(L-lysine) (PS-PPDA-PSS-MnFe 2 O 4 -PLL) 65 or within poly(L-arginine), human serum albumin, Fe 3 O 4 and poly(L-glutamic acid) (PLG-HAS-Fe 3 O 4 -PLG). 66 In some cases, polymers like PNIPAM (or other water-soluble polymers) have been attached on one side of a metal nanoparticle (Au or TiO 2 ) 67,68 to create asymmetry and take advantage of their photoresponsive properties.…”

External Field‐Driven Untethered Microrobots for Targeted Cargo Delivery

“…From this perspective, Noh et al designed a TiO 2 -based micromotor, on which one hemisphere was covalently connected with glucose oxidase (GO x ), and the opposite hemisphere was immobilized with water-soluble conjugated polymer (WSP) through electrostatic interaction. [111] The functions of the two substances are to decompose glucose into H 2 O 2 and to endow the TiO 2 with photocatalytic activity under visible light, respectively. Then, the produced H 2 O 2 can be degraded by the excited electrons and holes, resulting in different concentrations of H 2 O 2 and glucose, thus propelling the micromotor with a velocity of 7.49 µm s −1 via self-diffusiophoresis mechanism (Figure 11C).…”

Interactive and synergistic behaviours of multiple heterogeneous microrobots

“…Microrobots can be defined as motile microsystems powered by biological, chemical, and physical methods for a specific purpose 1 and have shown great potential in biomedicine. 2–5 Various types of microrobots driven by external physical fields (magnetic, 6–8 light, 9–11 and acoustic fields 12–14 ) have been designed for targeted drug delivery 15–17 and cell transportation 18–20 in recent years. In particular, the use of a magnetic field presented as a wireless power source has attracted considerable attention for its safety, ability to permeate deep tissue in the human body, spatiotemporal controllability, etc.…”