A novel pH-responsive hydrogel-based on calcium alginate engineered by the previous formation of polyelectrolyte complexes (PECs) intended to vaginal administration

Abstract

This work aimed to develop a calcium alginate hydrogel as a pH responsive delivery system for polymyxin B (PMX) sustained-release through the vaginal route. Two samples of sodium alginate from different suppliers were characterized. The molecular weight and M/G ratio determined were, approximately, 107 KDa and 1.93 for alginate_S and 32 KDa and 1.36 for alginate_V. Polymer rheological investigations were further performed through the preparation of hydrogels. Alginate_V was selected for subsequent incorporation of PMX due to the acquisition of pseudoplastic viscous system able to acquiring a differential structure in simulated vaginal microenvironment (pH 4.5). The PMX-loaded hydrogel (hydrogel_PMX) was engineered based on polyelectrolyte complexes (PECs) formation between alginate and PMX followed by crosslinking with calcium chloride. This system exhibited a morphology with variable pore sizes, ranging from 100 to 200 μm and adequate syringeability. The hydrogel liquid uptake ability in an acid environment was minimized by the previous PECs formation. In vitro tests evidenced the hydrogels mucoadhesiveness. PMX release was pH-dependent and the system was able to sustain the release up to 6 days. A burst release was observed at pH 7.4 and drug release was driven by an anomalous transport, as determined by the Korsmeyer-Peppas model. At pH 4.5, drug release correlated with Weibull model and drug transport was driven by Fickian diffusion. The calcium alginate hydrogels engineered by the previous formation of PECs showed to be a promising platform for sustained release of cationic drugs through vaginal administration.

Transformer Hydrogels: A Review

“…Cationic hydrogels have monomers with amine and amide groups such as AAm, dimethylaminoethyl methacrylate (DMAEMA), and 2‐(diethylamino)ethyl methacrylate (DEAEMA), and their copolymers. Hydrogels composed of biopolymers such as chitosan, alginate, albumin, and gelatin can also show pH responsivity and have excellent biocompatibility and biodegradability over their synthetic counterparts.…”

Mucoadhesive nanostructured polyelectrolytes complexes modulate the intestinal permeability of methotrexate

“…The molecular weight (Mw) and second virial coefficient (A 2 ) of CS, HA and HP were estimated by the static light scattering technic on a Zetasizer Nano ZS® (Malvern Instruments, Worcestershire, UK) equipment, using the Zetasizer nano ZS v7.11 software (Worcestershire, UK). Polymers dispersions, in different concentrations (0.02-0.9 mg·mL − 1 ) at 25°C were analysed implementing the Rayleigh equation, that describes the intensity of light scattered from the polymer structure in solution (Ferreira et al, 2017). The experiment was conducted using toluene, previously filtered through a polytetrafluoroethylene membrane (PTFE, 0.2 μm), as an equipment internal standard and ultra-pure water filtered through a cellulose acetate membrane (RC, 0.2 μm), as the blank.…”

Simple approach for cleaning up 2,4,6‐trichloroanisole from alcoholic‐beverage‐reconstituted solutions using polymeric materials

“…Each chain was separated by a distance of at least 5 Å, to give an alginate spherical nanoparticle of 80 Å diameter. Finally, as the carboxylate groups of the alginate chains are sensitive to change in pH (Cao et al , Ferreira et al ), their protonation states were considered. Therefore, three different alginate nanoparticles were built in order to simulate the environments in methanol solution (0% protonated), whisky (20% protonated) and red wine (70% protonated).…”