Permeability of silk microcapsules made by the interfacial adsorption of protein

Abstract

The assembly of colloidal particles at a liquid/liquid interface is a useful technique for the formation of a large variety of structures. Recently, we created a new method which uses liquid/liquid interfaces to assemble recombinant silk proteins into thin-shelled microcapsules. These microcapsules are mechanically stable and well suited to applications such as enzyme therapy and artificial cells. In this paper the permeability properties of these microcapsules are investigated using a novel measurement technique. It is found that the microcapsules are polydisperse in their permeabilities, but for all measured microcapsules the permeability is in the range required to protect encapsulants from immunoglobulin proteins, while allowing small molecules to enter the capsule freely.

Recombinant Spider Silks—Biopolymers with Potential for Future Applications

“…27 kDa), small molecules can freely diffuse through the membrane. The release of active substances from such capsules can be triggered by limited proteolysis of the spidroins [67,68].…”

Drop profile analysis tensiometry with drop bulk exchange to study the sequential and simultaneous adsorption of a mixed β-casein /C12DMPO system

“…These two types of surface active molecules show very different behaviour, regarding the adsorption mechanism, characteristic adsorption parameters as well as properties relevant for practical applications. Protein layers are used, for example, as templates for microscopic capsules, produced by chemical crosslinking of the protein structures [13] or mineralisation of protein aggregates [14]. Protein/surfactant mixtures at interfaces represent the standard situation in the process of fat digestion [15].…”

Production and processing of spider silk proteins

“…The microcapsules can be transferred into aqueous solution either via centrifugation into an aqueous sublayer or dilution of the toluene by the addition of an excess of ethanol and water. 50,51 The capsules are porous (with an average MW cutoff of 27 kDa) therefore allowing small molecules (such as fluorescein-a simple model for a low molecular weight drug) to diffuse freely (resulting in a burst release), whereas macromolecules (such as FITC labeled dextran-a simple model for a macromolecular drug) are retained within the capsules (provided they are larger than the cutoff). 50 The capsules can be degraded upon exposure to Proteinase K in a matter of minutes.…”

“…50,51 The capsules are porous (with an average MW cutoff of 27 kDa) therefore allowing small molecules (such as fluorescein-a simple model for a low molecular weight drug) to diffuse freely (resulting in a burst release), whereas macromolecules (such as FITC labeled dextran-a simple model for a macromolecular drug) are retained within the capsules (provided they are larger than the cutoff). 50 The capsules can be degraded upon exposure to Proteinase K in a matter of minutes. Interestingly this degradation can be prevented by chemically crosslinking the proteinaceous membrane of the capsules via photo-initiated oxidation with ammonium peroxodisulfate and tris(2,20-bipyridyl)dichlororuthenium(II).…”