Chitosan crosslinked microparticles with encapsulated polyphenols: Water sorption and release properties

Abstract

Chitosan-glutaraldehyde microparticles were produced by emulsion crosslinking method to be used as drug delivery system for polyphenols from Thymus serpyllum L. aqueous extract. The effect of preparation conditions, chitosan concentration (1.5-3% w/v), and glutaraldehyde/chitosan (GA/Ch) mass ratio (0.15-1.20) on water and polyphenols transport properties was investigated. Swelling ratio of dry particles (68-230 µm) in water ranged from 280% to 530%, depending on the formulation. The decrease in swelling was observed with increased GA/Ch mass ratio (i.e. crosslinking degree) at the same chitosan concentration, or with increased chitosan concentration at the same GA/Ch mass ratio. The increase in GA/Ch mass ratio was also manifested by increased particle compactness i.e. decreased size and reduced surface roughness. The sorption capacity for polyphenols seems to be a complex interplay of swelling behaviour and interactions chitosan-glutaraldehyde-polyphenols identified by Fourier transmission infrared analysis. An increase in crystallinity of chitosan was observed upon crosslinking with glutaraldehyde and encapsulation of polyphenols, as observed by X-ray diffraction analysis. The results obtained from release kinetics of selected polyphenolic compounds (caffeic acid, rosmarinic acid, total flavonoids, and total phenol content) showed that polyphenols were released at a lower amount (2-4 times) in water, but more rapidly (45-120 min) in comparison with the release in gastric followed by intestinal simulated fluid (SGF-SIF) (120-240 min). The experimental results of the time-dependent swelling in water and polyphenols release in both, water and SGF-SIF, were analyzed with several mathematical models. The results depicted Fickian diffusion as the water transport mechanism. In the case of polyphenols, only empirical Weibull model could be suggested for describing release kinetics.

Diffusion of polyphenols from alginate, alginate/chitosan, and alginate/inulin particles

“…The results indicate that the release from the composite particles exhibited anomalous diffusion of polyphenols controlled by molecular diffusion and polymer relaxation. Polyphenolic release associated with chitosan relaxation has been previously reported in literature (Trifkovic et al, ). The low value of exponent n for alginate particles can be probably ascribed to polymer relaxation or desorption of the nonencapsulated polyphenolic compounds from the external surface of the particles.…”

“…Some studies have shown that the effect of the molecular weight of chitosan on the alginate/chitosan particles size is higher than the alginate molecular weight (Murata, Nakada, Miyamoto, Kawashima, & Seo, ). Namely, the smaller molecule of chitosan penetrates deeper into the inside of the alginate/chitosan complex to form a smaller and more homogeneous particles, while large molecules are retained mainly on the surface, where they form a polyelectrolyte membrane by increasing the particle size (Trifkovic et al, ). As regarding the impact of inulin, it has not retarded significantly the thyme release after having insight into the whole time range in comparison to solely alginate ( p > 0.05).…”

Development and characterisation of functional cocoa (Theobroma cacao L.)‐based edible films

“…These results are in accordance with those obtained by Trifković et al . (), who reported on the lower extent of thyme‐derived hydroxycinnamic acids release from chitosan microbeads, possibly due to the presence of multiple hydroxyl groups in this group of polyphenols, which establish strong hydrogen and covalent bonds with amino groups present in the chitosan molecules. However, a higher rate of additional release in SIF was observed in the chitosan‐based films than in the alginate‐ and pectin‐edible films.…”

Short Overview of Encapsulation Technologies for Delivery of Bioactives to Food

“…The particles obtained via this technology are in the size range 10-1000 nm, and with a good sphericity [30,31]. An alternative way to produce biopolymer particles is the novel inverse emulsion technique [32,33,34]. This technique is called inverse since it implies production of water-in-oil emulsions, by dispersing the water solution of hydrophilic polymer in hydrophobic oil phase, with the assistance of water-in-oil type of emulsifier.…”