Enzymatically Powered Surface‐Associated Self‐Motile Protocells

Abstract

Cell motility is central to processes such as wound healing, immune cell surveillance, and embryonic development. Motility requires the conversion of chemical to mechanical energy. An active area of research is to create motile particles, such as microswimmers, using catalytic and enzymatic reactions. Here, autonomous motion is demonstrated in adhesive polymer-based protocells by incorporating and harnessing the energy production of an enzymatic reaction. Biotinylated polymer vesicles that encapsulate catalase, an enzyme which converts hydrogen peroxide to water and oxygen, are prepared and these vesicles are adhered weakly to avidin-coated surfaces. Upon addition of hydrogen peroxide, which diffuses across the membrane, catalase activity generates a differential impulsive force that enables the breakage and reformation of biotin-avidin bonds, leading to diffusive vesicle motion resembling random motility. The random motility requires catalase, increases with the concentration of hydrogen peroxide, and needs biotin-avidin adhesion. Thus, a protocellular mimetic of a motile cell.

Enzyme catalysis powered micro/nanomotors for biomedical applications

“…4g). 127 In another study, catalase containing organoclay/DNA semipermeable microcapsules were fabricated that displayed oxygen gas bubble dependent buoyancy (Fig. 4f).…”

“…Designs for catalase powered MNMs. (a) Mesoporous silica nanoclusters with magnetic control bound to catalase on one side,121 (b) polystyrene beads coated with catalase by biotin-streptavidin linkage,69 (c) biocompatible hydrogel fabricated by PEGDA and dextran,124 (d) polymeric (PEG-b-PS) stomatocytes encapsulated with enzymes,115 (e) biodegradable polymeric (PEG-b-PDLLA) nanotubes coated with catalase,125 (f) organoclay/DNA protocells encapsulated with enzymes,126 and (g) polymeric protocells encapsulated with catalase for autonomous motion 127. Adapted with permission from ref.121 and 125.…”

Dynamic Behaviour in Microcompartments

“…Upon the addition of H 2 O 2 ,w hich diffused through the membrane, catalase hydrolysed H 2 O 2 to produce ad ifferential impulse that caused the breakage and subsequentf ormation of the biotin-avidinb ond, resulting in random motion of the microcompartments. [64] Actin polymerisation acts as ap owerful propulsion mechanism in motility behaviours in bacteria, such as listeria. [67] Actin assembly-inducing protein (ActA) partly functionalised microcompartments were constructed to mimic the motility behaviour of listeria in the environment containing actin monomers and Arp2/3c omplex.…”

“…Biotinylated microcompartments were initially adhered weakly to an avidin‐coated surface. Upon the addition of H 2 O 2 , which diffused through the membrane, catalase hydrolysed H 2 O 2 to produce a differential impulse that caused the breakage and subsequent formation of the biotin–avidin bond, resulting in random motion of the microcompartments …”

Artificial morphogen-mediated differentiation in synthetic protocells

“…Building arrays of artificial cell-like entities capable of contact or non-contact modes of interaction is an emerging challenge in bottom-up synthetic biology. A wide range of synthetic protocells in the form of single compartmentalized microstructures have been constructed and used as biomimetic models of cell-free gene expression 1–4 , enzyme activity in crowded 5,6 , or confined 7,8 environments, artificial cytoskeleton reconstitution 9,10 , membrane gating 11 , motility 12–14 and membrane growth and division 15–17 . These design strategies have been extended to the construction of multi-compartmentalized microsystems comprising nested 18–22 or host-guest 23–25 arrangements of synthetic protocells and exploited in the programmed release of molecular cargos, positional assembly of functional components, and spatiotemporal regulation of enzyme cascade reactions.…”