Polyelectrolyte Complexation versus Ionotropic Gelation for Chitosan-Based Hydrogels with Carboxymethylcellulose, Carboxymethyl Starch, and Alginic Acid

Abstract

e preparation of gels by charge interaction methods has been extensively studied, but it is not yet clear how these methods influence gel characteristics. e objective of this work was to study differences in morphology and surface charge of hydrogels prepared by ionotropic gelation, polyelectrolyte complexation, and a combination of both methods. us, the anionic charge was provided by carboxymethylcellulose (CMC), carboxymethylated starch (CMS), and alginic acid (AA); calcium chloride (CaCl 2 ) and chitosan (CS) were used for the ionotropic gelation and polyelectrolyte complexation, respectively. ose materials are commercially available, have low toxicity, and are widely used in the area. ese compounds interact through physical crosslinks, which are affected by physical changes of the medium. Our results showed that these two methods produced changes in the morphology of the hydrogels. CMC gels exhibited larger pores in the presence of CaCl 2 . In polyelectrolyte complexation, CMS produced an increased agglomeration of particles, while the addition of CaCl 2 to AA generated dispersed particles of size in the order of millimeters. Mixing both ionotropic gelation and polyelectrolyte complexation methods yielded gels of varied charge (568 mV for CMC, 502 mV for CMS, and 1713 mV for AA). FTIR spectra of the hydrogels showed interactions between the different polymeric compounds, being the greatest changes between 1250 and 1600 cm −1 , due possibly to the replacement of Na by Ca at crosslinking points. erefore, the method of gel preparation employed had a major influence on the size and pore distribution, parameters which in turn influence encapsulation and drug delivery in these systems.

Starch-based hydrogels show relevant properties for tissue engineering and loading of nanoparticulate systems.

“…As a result, some differences among each spectrum were observed and the main peaks are identified in Table 1 . Three bands are consistently present in the four spectra: those related to C-O and C-O-C stretching: 1017-1022 cm -1 and 1079-1082 cm -1 , respectively; and the one about 3300 cm -1 , which is usually associated to the presence of -OH group (Henao, 2018). These bands have been previously observed in FTIR spectra of chitosan (Brugnerotto, 2001), PVA (Peng, 2019), and starch (Xu, 2005).…”

Ionotropic Gelation of Chitosan for Next-Generation Composite Proton Conducting Flat Structures

“…In contrast, ionotropic gelation is a procedure not deservedly developed in fuel cell literature, and thus, is confined to a very few papers [25,26]. Instead, ionotropic gelation is usually obtained by the polyelectrolyte complexation technique or crosslinking where hydrogels are formed by adding one polyelectrolyte to another polyelectrolyte having an opposite charge [36,37]. Given the ability to produce biocompatible materials, ionotropic gelation has been extensively developed in the biomedical field for the synthesis of gel beads, nanoparticles, micro/nanogels, and fibers [38][39][40][41].…”

Pectin and Zinc Alginate: The Right Inner/Outer Polymer Combination for Core-Shell Drug Delivery Systems

“…Among them prilling, also known as laminar jet break-up, has been considered a proper tool in creating polymeric hydrophilic microparticles (gel-beads) as modified delivery devices [36]. This technique essentially consists of two operations: the first is based on the breaking apart of a laminar jet of polymer solution into a row of mono-sized drops by means of a vibrating nozzle device, the second on their "solidification" through the ionotropic gelation method, exploiting the ability of polyelectrolyte polymers to cross-link in presence of counter ions [37][38][39]. Prilling technology offers different advantages; it is a mild and easy scalable microencapsulation technique that, if used in the co-axial configuration and in the proper operative conditions, could be used to obtain, in a single productive step, particles with multiple layers of different polymeric materials [40].The appropriate combination of two or more polysaccharides may be an effective way to prevent the early release of the drug in the upper part of the gastro-intestinal tract (GIT) that, as well known, represents the major drawback of oral formulations based on single polysaccharides [20,[41][42][43].…”