Gelation, ionic

An aqueous acidic solution of chitosan is added dropwise under constant stirring to sodium tripolyphosphate solution. Chitosan undergoes gelation due to the 

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Thermal and ionic gelation in liquid media Desolvation in liquid media... 

Hydrophilic nanoparticle carriers have important potential applications for the administration of therapeutic molecules [28,53]. Most of the recently developed hydrophobic-hydrophilic carriers require the use of organic solvents for their preparation and have a limited protein-loading capacity [54,55]. Calvo et al. [56] reported a new approach for the preparation of nanoparticles, made solely of hydrophilic polymer, to address these limitations. The preparation technique, based on an ionic gelation process, is extremely mild and involves the mixing of two aqueous phases at room temperature. 

Chitosan molecular weight has also been reported to influence drug release. Jiang et al. [94] studied Bordetella bronchiseptica dermonecrotoxin (BBD) release from chitosan microspheres prepared by tripolyphosphate ionic gelation. It has been shown that the BBD release rate increased with chitosan molecular weight decrease. It has been explained by the weaker BBD interaction with chitosan of lower molecular weight and lower content of free amine groups, responsible for their interaction. 

Microspheres Ionic gelation with tripolyphosphate Bordetella, bronchiseptica, dermonecrotoxin Chitosan In mice Systemic and mucosal immune responses induced 21... 

A-(2-Hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) is a water-soluble derivative of chitosan (CS), synthesized by the reaction between glycidyl-trimethyl-ammonium chloride and CS. HTCC nanoparticles have been formed based on ionic gelation process of HTCC and sodium tripolyphosphate (TPP). Bovine serum albumin (BSA), as a model protein drug, was incorporated into the HTCC nanoparticles. HTCC nanoparticles were 110-180nm in size, and their encapsulation efficiency was up to 90%. In vitro release studies showed a burst effect, followed by a slow and continuous release. Encapsulation efficiency was obviously increased with increase in initial BSA concentration [15]. 

Chitosan is a polycation whose charge density depends on the degree of acetylation and pH. So, chitosan chains are able to interact by electrostatic interactions with negatively charged molecules. It can form nanoparticles by ionic gelation with polyphosphates [19] and with nucleic acids [20-22]. 

Process selection around a core material is dependent upon core material properties such as thermal stability, viscosity if it is a liquid, particle size and shape if it is a solid, density, reactivity, and solubility. Processes such as spray chilling or spray coating can expose core materials to elevated temperatures for longer periods of time, compared to spray drying, as the mixture remains heated as it awaits pumping to an atomization nozzle. Other processes, such as coextrusion or some emulsion processes, can be carried out at or below room temperature. For example, ionic gelation coupled with coextrusion can be used to encapsulate oils or biological materials at or below room temperature." Processes like solvent evaporation can be operated under vacuum to remove the matrix solvent rather than the use of temperature. ... 

Ultimate properties of hydrogel beads prepared by ionotropic gelation depend mainly upon different factors, which affect the ionic gelation process. Some of the factors which affect ionotropic gelation... 

Methods Based on Ionic Interactions 36.3.4.1 Ionic Gelation... 

Quercetin Chitosan Complexation followed by ionic gelation Increased of dispersibiUty in water and bioavailability [171]... 

Hosseini, S. M., Hosseini, H., Mohammadifar, M.A., Mortazavian, A. M., Mohammadi, A., Khosravi-Darani, K., Shojaee-Aliabadi, S., Dehghan, S., and Khaksar, R. (2013). Incorporation of essential oil in alginate microparticles by multiple emulsion/ionic gelation process. International Journal of Biological Macromolecules, 62, 582-588. 

For instance, Yadav and Ahuja prepared nanoparticles using gum cordia as the polymer and to evaluate them for ophthalmic delivery of fluconazole. A w/o/w emulsion containing fluconazole and gum cordia in aqueous phase, methylene chloride as the oily phase, and dioctyl sodium sulfosuccinate and polyvinyl alcohol as the primary and secondary emulsifiers, respectively, were cross-linked by the ionic gelation technique to produce a fluconazole-loaded nanoreservoir system. The formulation of nanoparticles was optimized using response surface methodology. Multiple response simultaneous optimizations using the desirability approach were used to find optimal experimental conditions. The optimal conditions were found to be concentrations of gum cordia (0.85%, w/v), di-octyl sodium sulfosuccinate (9.07%, w/v), and fluconazole (6.06%, w/v). On comparison of the optimized nanosuspension formulation with commercial formulation, it was found to provide comparable in vitro corneal permeability of... 

We have recently adopted a novel chitosan-based ionic gelation process for the preparation of PMAA-based microparticles. " Methacrylic acid was polymerized in the presence of chitosan in aqueous medium, and particles were obtained spontaneously during the polymerization without the addition of any organic solvents and steric stabilizers. PMAA-CS particles displayed good protein encapsulation efficiency and demonstrated pH responsive release behavior at stimulated gastric and intestinal pH. Application of these microparticles toward oral protein delivery was evaluated using insulin and bovine serum albumin (BSA) as model proteins. 

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