Catalytic processing in ruthenium-based polyoxometalate coacervate protocells

Abstract

The development of programmable microscale materials with cell-like functions, dynamics and collective behaviour is an important milestone in systems chemistry, soft matter bioengineering and synthetic protobiology. Here, polymer/nucleotide coacervate micro-droplets are reconfigured into membrane-bounded polyoxometalate coacervate vesicles (PCVs) in the presence of a bio-inspired Ru-based polyoxometalate catalyst to produce synzyme protocells (Ru4PCVs) with catalase-like activity. We exploit the synthetic protocells for the implementation of multi-compartmentalized cell-like models capable of collective synzyme-mediated buoyancy, parallel catalytic processing in individual horseradish peroxidase-containing Ru4PCVs, and chemical signalling in distributed or encapsulated multi-catalytic protocell communities. Our results highlight a new type of catalytic micro-compartment with multi-functional activity and provide a step towards the development of protocell reaction networks.

Interface Engineering in Multiphase Systems toward Synthetic Cells and Organelles: From Soft Matter Fundamentals to Biomedical Applications

“…[39,131,150,233,247,259,[328][329][330][331][332][333][334][335] The GOx-HRP cascades can also be performed in coacervate droplets as membraneless organelles, by cationizing or anionizing GOx and HRP respectively (Figure 16a). [233,247,253,259,270,333,334,336,337] A complicated version of the glucose cascade is presented in a synthetic beta cell, a multicompartmental vesosomes composed of an outer vesicle with glucose transporter 2 (GLUT2) and inner pH-responsive vesicles containing insulin (Figure 16b). [14] Glucose is taken up by the outer vesicle of which GLUT2 and gramicidin A are anchored in the membrane, and it is oxidized by encapsulated GOx into gluconic acid, lowering the local pH.…”

“…[14] Most two-enzyme, three-enzyme, and multiple-enzyme cascades are demonstrated in multicompartmental vesiclein-vesicle. [337][338][339] For instance, two interior polymersomes encapsulate either Candida antarctica lipase B (CalB) or alcohol dehydrogenase (ADH), which are then coencapsulated into a large polymersomes together with a third enzyme, phenylacetone monooxygenase (PAMO) and nicotinamide adenine dinucleotide phosphate (NADPH), and profluorescent substrate (Figure 13c). [338] The profluorescent substrate is oxidized by PAMO and NADPH as a cofactor, then the product is hydrolyzed by CalB, the product of which is oxidized by ADH and cofactor NAD + , yielding the final product.…”

“…The regeneration of cofactor NADPH have also been demonstrated in other cascades in multicompartmental synthetic cells. [337,340]…”

“…Reproduced under the terms of the CC‐BY Creative Commons Attribution 4.0 International license ( http://creativecommons.org/licenses/by/4.0). [ 337 ] Copyright 2020, The Authors, published by Springer Nature. b) Schematic and fluorescence microscopy images of a complex cascade in a vesicle‐in‐vesicle synthetic beta cell, which secretes insulin in response to an increase of glucose in surroundings.…”

Nucleation mechanisms and speciation of metal oxide clusters

“…1 Although the rst-ever characterized structure was synthesized by Berzelius almost two centuries ago, 2 POMs have not ceased to attract attention. As a matter of fact, they display a broad variety of present applications in catalysis, [3][4][5][6][7][8][9][10][11] nuclear reprocessing, 12,13 electro-chemistry 14 and potential uses in information technologies, 15,16 medicine, [17][18][19] and energy. [20][21][22] The synthesis of POMs usually takes place by reacting the corresponding oxo-anion monomer, for instance [MoO 4 ] 2À , with additional acids, bases or other salts, in aqueous solution where a plethora of hydrolysis, aggregation and condensation reactions triggers the formation of discrete clusters.…”