Structural Effects of pH Variation and Calcium Amount on the Microencapsulation of Glutathione in Alginate Polymers

Abstract

Reduced glutathione (GSH) has a high antioxidant capacity and is present in nearly every cell in the body, playing important roles in nutrient metabolism, antioxidant defense, and regulation of cellular events. Conversely, alginate is a macromolecule that has been widely used in the food, pharmaceutical, biomedical, and textile industries due to its biocompatibility, biodegradability, nontoxicity, and nonimmunogenicity as well as for its capabilities of retaining water and stabilizing emulsions. The primary goal of this study was to characterize and optimize the formation of a molecular complex of calcium alginate with GSH using a computational approach. As methods, we evaluated the influence of varying the amount of calcium cations at two different pHs on the structural stability of Ca2+-alginate complexes and thus on GSH liberation from these types of nanostructures. The results showed that complex stabilization depends on pH, with the system having a lower Ca2+ amount that produces the major GSH release. The systems at pH 2.5 retain more molecules within the calcium-alginate complex, which release GSH more slowly when embedded in more acidic media. In conclusions, this study demonstrates the dependence of the amount of calcium and the stabilizing effect of pH on the formation and subsequent maintenance of an alginate nanostructure. The results presented in this study can help to develop better methodological frameworks in industries where the release or capture of compounds, such as GSH in this case, depends on the conditions of the alginate nanoparticle.

Development and Evaluation of Cross-Linked Alginate–Chitosan–Abscisic Acid Blend Gel

“…The three-dimensional structures of β-D-mannopyranuronate (M) and α-L-gulopyranuronate (G) were obtained based on previous work conducted in our laboratory [26]. Similarly, the structure of abscisic acid (ABA) was obtained from a protein structure cocrystallized with ABA (PDB code: 3JRQ), and the chitosan polymer structure was obtained from a study by Valdes et al (2021) [27].…”

“…Similarly, the structure of abscisic acid (ABA) was obtained from a protein structure co-crystallized with ABA (PDB code: 3JRQ), and the chitosan polymer structure was obtained from a study by Valdes et al (2021) [27]. The pKa values for M (approximately 3.4) and G (approximately 3.6) were obtained from Bustos et al (2022) [26], while the pKa value for ABA was evaluated using the Epik software from the Maestro-Schrödinger program [28].…”

“…For the construction of each of the three different systems (1:1, 1:2, and 2:1 alginate: chitosan ratios), they underwent energy minimization using the same conditions as described by Bustos et al (2022) [26]. The systems were simulated using the Desmond/ Maestro-Schrödinger suite [28], and the OPLS v.2005 force field [30] was applied.…”

“…The systems were simulated using the Desmond/ Maestro-Schrödinger suite [28], and the OPLS v.2005 force field [30] was applied. The default relaxation protocol was employed, consisting of five short simulations, following the protocols outlined in Bustos et al (2022) [26]. The production simulations were performed in an NPT ensemble at ambient conditions (pressure = 1 atm and temperature = 300 K), with a duration of 100 ns for each system, performed in triplicate.…”

Calcium-Alginate-Chitosan Nanoparticle as a Potential Solution for Pesticide Removal, a Computational Approach

“…One of the major advantages of alginate is its ability to form hydrogels in the presence of divalent cations, such as Ba 2+ , Ca 2+ , Sr 2+ , Cu 2+ , Zn 2+ , Ni 2+ , and Mn 2+ [ 35 , 36 ]. The chemical structure of alginate consists of a linear chain of β-(1→4)-linked D-mannuronic acid (M) and L-guluronic acid (G) residues [ 37 , 38 , 39 , 40 ]. These natural biopolymers have a wide range of applications in various fields such as food, pharmaceuticals, and biomedicine.…”