Alginate, ionotrope gelation

The vibration system is theoretically based on liquids with Newtonian flnid dynamics however, it was reported by Serp et al. that it can be applied to non-Newtonian liquids such as alginate, to make uniform drops and therefore microspheres by ionotropic gelation." The different equations can thereby be used as an approximation of the frequency and flow rates needed to break up the polymer into particles, however, it was suggested by Serp et al. and by Whelehan and Marison to determine the required values for a given nozzle diameter with an empirical approach for each system in which the calculated value is used as a starting (reference) point." It must also be noted that the size of the droplet does not necessarily equal the size of the produced bead/sphere. ... 

Poncelet, D., Babak, V., Dulieu, C., and Picot, A. A physico-chemical approach to production of alginate beads by emulsification-intemal ionotropic gelation. Coll. Surf. A Physiochem. Eng. Aspects 155 (1999) 171-176. 

MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazoIium) assay. Saraei et al. [40] investigated alginate nanoparticles containing a model protein, bovine serum albumin (BSA), by the ionotropic gelation technique. The average particle size of the BSA-loaded alginate nanoparticles was 50nm, the zeta potential was -24 mV, and the polydispersity index was 0.36. 

Oral delivery of insulin is important because endogenous insulin enables prolonged control of the glycenuc effect in diabetic patients. Mukhopadhyay et al. [66] formulated chitosan/alginate nanoparticles by simple ionotropic gelation techniques for insulin delivery. The particle size range of the nanoparticle was 100-200nm, and the encapsulation efficiency of insulin was approximately 85%. The in vitro release of insulin was 26.7% for 2h in acidic medium (pH 1.2) and 79-84% for approximately 24h in intestinal medium (pH 6.8 and 7.4). The in vivo evaluation showed an increase... 

The major advantages of ionotropic gelation are that capsules are easily prepared in aqueous solutions and at room temperature, enabling the method to be used for heat-labile materials. The drawback of this method includes very low payload, unacceptable cost-in-use, large capsules size, limited range of waU materials and undesirable amounts of substantial polymers incorporated into the foods. In order to improve this technique, hydrophobicaUy modified starch, epimerized alginate and polyelectrolyte-based multilayer microcapsules can be used to increase the payload. 

Chitosan is a promising polymer for colon delivery because it can be biodegraded by the colonic microflora and it has mucoadhesive character. A thorough study has been carried out on chitosan beads obtained by ionotropic gelation with alginate or tripolyphosphate. The aim was to develop, using natural polymers, a controlled release system that would resist the conditions in the stomach and release its drug... 

Figure 10.10 Ionotropic gelation by interaction between anionic groups on alginate (COO )... 

In a study, microbeads of khaya gum with sodium alginate were prepared via ionotropic gelation by using zinc chloride solution as the crosslinking agent. The microbeads possessed particle sizes betwwen 1.48-2.41 pm and entrapment efficiencies were in the range of 44.0-71.3% w/w, while the release form fitted the Korsmeyer-Peppas model [17]. 

In another trial, microparticles of sodium alginate were produced by ionotropic gelation process in a microencapsulation application and achieved a drug entrapment efficienty of higher than 97% [15]. 

Sarmento, B., Ribeiro, A.J., Veiga, F., Ferreira, D.C., Neufeld, R.J., 2007. Insulin-loaded nanoparticles are prepared by alginate ionotropic pre-gelation followed by chitosan polyelectrolyte complexation. J. Nanosci. Nanotechnol. 7 (8), 2833-2841. 

Das et al. reported a nanoformulation with a tripolymeric composite carrier (alginate, chitosan and Pluronic) by ionotropic pre-gelation followed by polycationic crosslinking for the deUvery of curcumin to cancer cells. The IC50 values for fi"ee curcumin and encapsulated curcumin on Hela cells were found to be 13.28 and 14.34 pM, respectively. The green fluorescence inside the Hela cells visualized using fluorescent microscopy confirmed the cellular internalization of curcumin-loaded composite NPs [ 133]. A simple nanoprecipitation method resulted... 

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