Electrostatically gated membrane permeability in inorganic protocells

Abstract

Although several strategies are now available to produce functional microcompartments analogous to primitive cell-like structures, little progress has been made in generating protocell constructs with self-controlled membrane permeability. Here we describe the preparation of water-dispersible colloidosomes based on silica nanoparticles and delineated by a continuous semipermeable inorganic membrane capable of self-activated, electrostatically gated permeability. We use crosslinking and covalent grafting of a pH-responsive copolymer to generate an ultrathin elastic membrane that exhibits selective release and uptake of small molecules. This behaviour, which depends on the charge of the copolymer coronal layer, serves to trigger enzymatic dephosphorylation reactions specifically within the protocell aqueous interior. This system represents a step towards the design and construction of alternative types of artificial chemical cells and protocell models based on spontaneous processes of inorganic self-organization. Colloidosomes based on silica nanoparticles self-assembled at water droplet/oil interfaces are promising inorganic protocells, but they often leak small molecules on transfer into bulk water. Through silane crosslinking and copolymer grafting, colloidosomes have now been endowed with membranes that exhibit pH-responsive permeability to small molecules. The resulting water-dispersible colloidosomes further serve to host and control enzyme reactions.

Cite this article

Li, M., Harbron, R., Weaver, J. et al. Electrostatically gated membrane permeability in inorganic protocells. Nature Chem 5, 529–536 (2013). https://doi.org/10.1038/nchem.1644

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