Electrostatic Interactions in Aqueous Solutions of Ionic Polysaccharides

Preparation and characterization of vitamin A microcapsules nutrient fortified salt

Vitamin A, also known as retinol, is a fat-soluble vitamin that plays crucial role in various physiological functions In vivo. However, factors such as light, oxygen, and others may impact the stability of VA. To enhance its stability. This study microencapsulated VA, Gelatin, carboxymethyl cellulose, and salt were mixed in a ratio of 5:1:0.1 as the shell material. Additionally, 12% TG and 3.5% sucrose ester were added with core-shell ratio of 1:8. The experimental results indicated that VA microcapsules exhibited an encapsulation efficiency of 81.12%, after 9 weeks of storage this rate decreased to 75.38%, and the encapsulated VA oil did not exhibit extravasation. The addition of an appropriate amount of salt to the shell material enhanced the mechanical properties of the shell material, compared to the shell material without added salt, the leakage of VA in the salt-added sample decreased by 5.8% for 30 min and 14.5% for 60 min. In vitro release experiments showed that after 3 h of incubation in simulated gastric fluid, the microcapsules had an 18.52% release rate. In simulated intestinal fluid, this increased to 66.58%, indicating strong enteric solubility.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05962-w.

Dilute polyelectrolyte solutions: recent progress and open questions

Polyelectrolytes are a class of polymers possessing ionic groups on their repeating units. Since counterions can dissociate from the polymer backbone, polyelectrolyte chains are strongly influenced by electrostatic interactions. As a result, the physical properties of polyelectrolyte solutions are significantly different from those of electrically neutral polymers. The aim of this article is to highlight key results and some outstanding questions in the polyelectrolyte research from recent literature. We focus on the influence of electrostatics on conformational and hydrodynamic properties of polyelectrolyte chains. A compilation of experimental results from the literature reveals significant disparities with theoretical predictions. We also discuss a new class of polyelectrolytes called poly(ionic liquid)s that exhibit unique physical properties in comparison to ordinary polyelectrolytes. We conclude this review by listing some key research challenges in order to fully understand the conformation and dynamics of polyelectrolytes in solutions.

Experimental approaches to hyaluronan structure

A review of the literature describing experimental studies on hyaluronan (HA) is presented. Methods sensitive to the hydrodynamic properties of HA, analyzed in neutral aqueous solution containing NaCl at physiological concentration, can be shown to fit the expected behavior of a high molecular weight linear semi-flexible polymer. The significant nonideality of HA solutions can be predicted by a simple treatment for hydrodynamic interactions between polymer chains. Nuclear magnetic resonance and circular dichroism studies of HA are also in agreement with a model incorporating dynamically formed and broken hydrogen bonds, contributing to the semi-flexibility of the polymer chain, and segmental motions on the nanosecond time scale. HA shows the capability for self-association in the formation of a viscoelastic putty state at pH 2.5 in the presence of salt, and a gel state at pH 2.5 in mixed organic/aqueous solution containing salt. Ordered and associated structures have also been observed for HA on the surfaces, especially in the presence of surface-structured water. These phenomena can be understood in terms of counterion-mediated polyelectrolyte interactions. The possibility that hyaluronan exists in vivo in environments that induce ordered structures and assemblies is discussed.

Purificação e caracterização de quitosana comercial

RESUMO: Procedimentos adequados para as purificações de quitosana comercial como cloridrato e na forma neutralizada são descritos. As amostras obtidas apresentam elevado grau de pureza e baixo teor de cinzas conforme verificado através de termogravimetria. As determinações de graus de acetilação por espectroscopia de ressonância magnética nuclear (<img width=32 height=32 src="http://img/fbpe/po/v8n4/8292s1.gif" align=absmiddle > ou = 23,6%) e por titulações (<img width=32 height=32 src="http://img/fbpe/po/v8n4/8292s1.gif" align=absmiddle > ou = 23,0%) apresentam muito boa concordância. O cloridrato de quitosana é solúvel em água, o que permite determinações de viscosidade intrínseca em solventes aquosos na ausência de excesso de ácido e facilita a comparação de quitosana com outros polieletrólitos quanto a estimativas de rigidez/flexibilidade.