Release of small hydrophilic molecules from polyelectrolyte capsules: Effect of the wall thickness

Abstract

Polymer nanocapsules assembled on cationic liposomes have been built through the layer-by-layer (LbL) technique. Chitosan and alginate, two biocompatible polyelectrolytes, were used to cover the template, where the Rhodamine B was previously loaded. The multishell formed with the alternate deposition of the polyelectrolytes, according to the principles of the LbL assembly, was supposed to change the permeability of the capsule wall. The thickness of the multishell was seen increasing with the number of layers deposited through the observations with the Transmission Electron Microscope. The permeability of the capsules was studied through Rhodamine B release assays. Nanocapsules with seven layers of polyelectrolytes released the dye slowly compared to the capsules with three or five layers. The Ritger-Peppas model was applied to investigate the release mechanisms and a non-Fickian transport behavior was detected regardless of the number of layers. Values of diffusion coefficients of Rhodamine B through the capsule wall were also calculated.

Design and production of hybrid nanoparticles with polymeric-lipid shell–core structures: conventional and next-generation approaches

“…Up to now, the methods usually employed for liposome covering by chitosan are based essentially on dropwise bulk methods 13,18,[24][25][26][27][28][29] such as the layer-bylayer (LbL) method. 30,31 Some efforts have been made towards improvement of these conventional methods using, for example, a supercritical reverse-phase evaporation method, 32 by exploiting complex and expensive apparatus.…”

Polymer Capsules for Enzymatic Catalysis in Confined Environments

“…Cuomo and coworkers reported that low or high molecular weight molecules were released with a non-Fickian type of transport from polyelectrolyte capsules made of alginate and chitosan. The release rate decreased, while the molecular weight and the multishell thickness increased [42,43] (Figure 2).…”

“…Multilayer film PLL c /liposomes/PMAc/PVP/PMA SH [19,82] Alginate/Chitosan Multilayer film ALG/CHI [7,22,42,43] Poly(sodium-styrene sulfonate)/poly(allylamine) hydrochloride Multilayer film PSS/PAH [5] Glucose oxidase/Catalase Multilayer film GOX/CAT [79] Glucose oxidase/polyethylenimine/Catalase Multilayer film GOX/PEI/CAT [80]…”

“…A schematic representation of the effect of the multishell thickness on the molecule release (reproduced with permission from[42], Copyright 2015, Elsevier).…”

Modelling mass diffusion for a multi-layer sphere immersed in a semi-infinite medium: application to drug delivery

“…In the classical book of Crank [5], the diffusion in a sphere from a well-stirred medium is solved by Fourier expansion in the case of constant or time varying surface concentration and the case of a constant flux at the surface. More recent work includes empirical, semi-empirical and mechanistic diffusion models [9]. An exact solution for diffusional release of a dispersed solute from a spherical polymer matrix into both semi-infinite and finite external mediums has been developed [10,11].…”