Release of Insulin from Calcium Carbonate Microspheres with and without Layer-by-Layer Thin Coatings

Abstract

Abstract:The release of insulin from insulin-containing CaCO 3 microspheres was investigated. The microspheres were prepared by mixing aqueous solutions of CaCl 2 and Na 2 CO 3 in the presence of insulin. The surface of the insulin-containing CaCO 3 microspheres was coated with a layer-by-layer thin film consisting of poly(allylamine hydrochloride) and poly(styrene sulfonate) to regulate the release kinetics of insulin. The release rate of insulin from the coated CaCO 3 microspheres was significantly suppressed compared with that of uncoated CaCO 3 microspheres, and depended on the thickness of the films. Rhombohedral calcite crystals of CaCO 3 formed from the microspheres during the release of insulin, suggesting that the CaCO 3 microspheres dissolved and recrystallized during the release of insulin.

Protein‐Containing Multilayer Capsules by Templating on Mesoporous CaCO3 Particles: POST‐ and PRE‐Loading Approaches

“…This may be explained by steric restrictions for the protein molecules to enter small pores of CaCO 3 microparticles during loading by adsorption because the pore size (20–60 nm) is comparable with protein dimensions (3–10 nm). The results above are in a line with that reported earlier for protein encapsulation by co‐synthesis . However, we believe that the mechanism of protein inclusion into the CaCO 3 microparticles by co‐synthesis is based on the trapping of the protein molecules into the pores of the CaCO 3 particles during the particle growth.…”

Loading Capacity versus Enzyme Activity in Anisotropic and Spherical Calcium Carbonate Microparticles

“…Our study shows that particles of different shapes, and microcapsules built on such particles, can serve as microcarriers in a broad range of applications, including those that allow tuning of permeability and release; 70 this can be achieved by varying the density of charges, 71 or by the number of applied polyelectrolyte layers. 72,73 The catalytic activity of enzymeloaded spherical and star-like particles decreases with the increasing number of layers (Figure 4). A decrease of activity by 4 times for small spherical particles, 3.5 times for star-like, and 2.5 times for large spherical particles already occurs with the presence of at least two layers of polyelectrolytes.…”

The influence of the size and aspect ratio of anisotropic, porous CaCO3 particles on their uptake by cells

“…In this work we have prepared three different shapes: porous spherical, ellipsoidal, and cuboidal particles [ 69 ], using a new method in which unequal concentrations of the interacting salts were used, and compare them with porous spherical calcium carbonate as well as commercially available smooth silica particles serving as control. The particles were coated with polyelectrolytes, so that the surface charges are adjusted, while on the other hand this coating could allow constructing capsules with the possibility of controlled release [ 70 – 74 ]. During the course of our work, we have also varied the sizes [ 75 ] of calcium carbonate particles using yet another innovative approach, in which ethylene glycol was used to slow down the course of the reaction, thus providing data on the influence of the size of particles on their uptake by cells.…”