Controlling surface porosity and release from hydrogels using a colloidal particle coating

Diffusion through colloidosome shells

“…We find that colloidal monolayers hinder transport when compared to uncoated systems. However, the reduction in diffusion is independent of the particle size, in agreement with our recent experimental results [14]. However, in the case of thick layers, the model predicts that decreasing the colloidal particle size should cause a significant reduction in the rate of transport, as indeed observed by Kim et al [11].…”

“…In a more detailed study, Kim et al [11] found that the permeability of a small-molecule diffusant through buckled, multi-layered colloidosome shells decreases with the size of the colloidal particles composing the shell. In contrast, we have recently shown that although a monolayer of colloidal particles hinders the transport of small hydrophilic diffusants (caffeine and aspirin) when compared to uncoated gels, the flux is independent of the colloidal particle size [14].…”

“…(8)) for three systems: Uncoated cores (namely, where / = 0), shells composed of relatively small colloidal particles where 2b = 20 nm, and shells composed of larger particles where 2b = 2 lm. The volume fraction in the two latter cases shells is taken to be 1/3, which corresponds to the value estimated in previous experiments [14]. It should be noted that due to the self-assembled nature of the colloidal shell in these systems, the The core, whose radius is a, may be composed of either an aqueous solution or a crosslinked hydrogel sphere.…”

“…The colloidal particles adhere to the core surface through forces such as electrostatic interactions or interfacial interactions [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In recent years, the trademark of colloidosomes as a delivery device has been the ability to control porosity, and thus, permeability, through choice of the colloidal particle size, which can range from nanometers to microns [9][10][11][12][13][14]. Lee and Weitz [13] find that a small-molecule diffusants can freely pass through shells composed of colloidal particles that are 10-20 nm, while a larger drug cannot, presumably due to size exclusion.…”

Colloidosomes: Synthesis, properties and applications

“…Rossenberg et al 80,81 conducted a series of release experiments from hydrogels covered with a monolayer of spherical particles. They systematically varied the particle diameter in order to achieve different pore sizes and monitored the release of small molecules such as aspirin and caffeine and also higher molecular weight dextran (~ 3-5 x 10 3 g mol -1 ).…”