Destruction of Polyelectrolyte Microcapsules Formed on CaCO3 Microparticles and the Release of a Protein Included by the Adsorption Method

Abstract

The degradation of polyelectrolyte microcapsules formed on protein-free CaCO3 particles consisting of polyallylamine (PAH) and polystyrene sulfonate (PSS) and the resulting yield of protein in the presence of various salts of different concentrations, as well as at two pH values, was studied by fluorescence spectroscopy; the protein was incorporated into prepared microcapsules by adsorption. It was found that a high concentration of sodium chloride (2 M) leads to considerable dissociation of PAH, which is apparently due to the loosening of polyelectrolytes under the action of ionic strength. At the same time, 0.2 M sodium chloride and ammonium sulfate of the same ionic strength (0.1 M) exert less influence on the amount of dissociated polymer. In the case of ammonium sulfate (0.1 M), the effect is due to the competitive binding of sulfate anions to the amino groups of the polyelectrolyte. However, unlike microcapsules formed on CaCO3 particles containing protein, the dissociation of polyelectrolyte from microcapsules formed on protein-free particles increased with increasing temperature. Apparently, a similar effect is associated with the absence of a distinct shell, which was observed on microcapsules formed on protein-containing CaCO3 particles. The high level of the presence of Fluorescein isothiocyanate (FITC)-labeled Bovine Serum Albumin (BSA) in the supernatant is explained by the large amount of electrostatically bound protein and the absence of a shell that prevents the release of the protein from the microcapsules. In 2 M NaCl, during the observation period, the amount of the released protein did not exceed 70% of the total protein content in the capsules, in control samples, this value does not exceed 8%, which indicates the predominantly electrostatic nature of protein retention in capsules formed on protein-free CaCO3 particles. The increase in protein yield and peeling of PAH with increasing pH is explained by the proximity of pH 7 to the point of charge exchange of the amino group of polyelectrolyte, as a result of the dissociation of the microcapsule.

Designing Functionalized Polyelectrolyte Microcapsules for Cancer Treatment

“…Note that the efficiency of loading DOX into MCs with the same structure at room temperature was earlier reported to not exceed ~55% if the pH and ionic strength of the MC microenvironment remained unchanged [12]. The amount of DOX loaded by this method in our study may have been increased because, in the alkaline medium (pH 8.0) and in the presence of NaCl, the permeability of the polyelectrolyte shell was changed [39].…”

“…It is noteworthy that the release of DOX from MCs(8L) was more intense compared to DOX-containing MBs and MBs(+8L). This could be accounted for by a higher permeability of the polyelectrolyte shell of the shell-type MCs because of a decreased charge density of PAH as a weak polyelectrolyte (with a pKa of about 8.5) [39]. Usually, when the core has been dissolved, the layers of the polyelectrolyte shell may be rearranged, which also alters the permeability of the polyelectrolyte structure, in contrast to core/shell MCs, where the shell, which is located on the core surface, is more stable [41].…”

LbL Nano-Assemblies: A Versatile Tool for Biomedical and Healthcare Applications

“…This technique affords a high loading of the therapeutic due to the high surface area of the porous particle and is applicable to a series of materials of different sizes, from proteins to low molecular weight drugs. Sacrificial templates, such as inorganic nanoparticles [ 19 , 20 ], carbon nanotubes [ 21 ], quantum dots [ 22 ], etc., can be removed using conditions that do not significantly affect the activity of the loaded therapeutic, forming capsules with high loadings. Besides, it is inexpensive, environmentally friendly, and all the deposition stages can be performed under mild conditions.…”

A Study of the Buffer Capacity of Polyelectrolyte Microcapsules Depending on Their Ionic Environment and Incubation Temperature

“…In addition, a number of works show changes in the PMC morphology, their cut thickness, and the migration of their polyelectrolyte layers, depending not only on the composition of the PMC shell, the presence of an encapsulated protein, or the presence of sodium chloride, but also on the ionic strength of the solution and the temperature of the medium [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. This may also indicate a possible dependence of the buffer capacity of polyelectrolyte microcapsules on these conditions.…”