Towards the inkjet fabrication of artificial cells

A novel method for the fabrication of cell-like microparticles consisting of a hydrogel core and a mesoporous silica shell has been developed. It consists of two steps: (i) inkjet fabrication of calcium alginate cores in the size range of 40–90 μm that can contain immobilised nanoparticles and liposome-based internal compartments; (ii) a sol–gel process for depositing a thin mesoporous silica layer on the microparticle surface using alkoxysilane precursors. The structure of the silica coating has been investigated and its effect on the diffusion rates of proteins with increasing molecular weight (lysozyme, myoglobin, ovalbumin and BSA) has been determined. The silica shell was shown to act as an efficient semi-permeable barrier that allows the diffusion of smaller proteins but rejects larger ones.

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► Alginate hydrogel microcapsules fabricated by drop-on-demand method.
► Sub-micron mesoporous silica layer deposited by sol–gel approach.
► Diffusion rates of proteins investigated.
► Liposomes and nanoparticles successfully encapsulated.