Self-propelled colloids are emerging as model systems for active matter. In the form of Janus structures, they are asymmetrically coated with a catalyst to function as chemical motors. It is desirable to replace the inorganic catalysts and the toxic fuels that are most often used with biocompatible enzymatic reactions. However, these are often less efficient. Here, we report a novel colloidal construct that makes use of bacteriophages and that exhibits very high enzymatic activities.<br/>The immobilization of enzymes to inorganic supports often reduces the turnover rate of the enzymes. Nevertheless, inorganic surfaces and colloids offer many advantages for heterogeneous catalysis. For instance, magnetic colloids facilitate the recovery of the enzymes. We show that bacteriophages represent a proteinaceous microenvironment where the enzymes maintain the high activity typically found in homogeneous catalysis, and thus use the phages to link enzymes to magnetic colloids. We have genetically modified M13 bacteriophages such that they could be bound to the colloids via a His-tag. Due to the high aspect ratio and flexibility of the phages, it is possible to obtain a high local concentration of enzymes while ensuring the unhindered diffusion of substrate and product molecules. Enzymes were covalently bound to the main coat protein of the M13 bacteriophages, thus ensuring a high enzyme-coverage of the particles. The enzymes retained their activity over many catalytic cycles. The magnetic colloids permit the convenient recovery of the enzymes. Localizing these constructs with a magnetic field, allows the enzyme-bacteriophage-particle system to function as an enzymatic-micropump, where the enzymatic reaction generates fluid flow in a microchannel. Particle tracking was used to analyze the pumping effect of urease bound to the bacteriophages and it is shown that the colloidal bacteriophage system shows the fastest fluid flow reported by an enzymatic micropump to date.

Phage colloids: Bacteriophages link enzymes to magnetic colloids for catalysis and micropumps

256th National Meeting (2018)

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