Immobilization of cells by electrostatic droplet generation: a model system for potential application in medicine

Abstract

Abstract:The process of electrostatic extrusion as a method for cell immobilization was investigated that could be used for potential applications in medicine. An attempt was made to assess the effects of cell addition and polymer concentration on the overall entrapment procedure, ie, on each stage of immobilization: polymer-cell suspension rheological characteristics, electrostatic extrusion process, and the process of gelation. The findings should contribute to a better understanding of polymer-cell interactions, which could be crucial in possible medical treatments. Alginate-yeast was used as a model system for carrier-cells. The electrostatic extrusion was considered as a complex two-phase flow system and the effects of cell and alginate concentrations on the resulting microbead size and uniformity were assessed. Under investigated conditions, microbeads 50-600 µm in diameter were produced and the increase in both alginate and cell concentrations resulted in larger microbeads with higher standard deviations in size. We attempted to rationalize the findings by rheological characterization of the cell-alginate suspensions. Rheological characterization revealed non-Newtonian, pseudoplastic behavior of cell-alginate suspensions with higher viscosities at higher alginate concentrations. However, the presence of cells even at high concentrations (5x10 8 and 1x10 9 cells/mL) did not significantly affect the rheological properties of Na-alginate solution. Lastly, we investigated the kinetics of alginate gelation with respect to the quantity of Ca 2+ ions and cell presence. The gelation kinetics were examined under conditions of limited supply with Ca 2+ ions, which can be essential for immobilization of highly sensitive mammalian cells that require minimal exposure to CaCl 2 solution. The molar ratio of G units to Ca 2+ ions of 3.8:1 provided complete crosslinking, while the increase in alginate concentration resulted in prolonged gelation times but higher strength of the resulting gel. The cell presence decreased the rate of network formation as well as the strength of the obtained Ca-alginate hydrogel.

Alginate microsphere fabrication using bipolar wave-based drop-on-demand jetting

“…The effects of the sodium alginate concentration on droplet formation have long been of interest and it is found that there is a concentration range for good droplet formation [8,19]. As found from Fig.…”

Calcium–Alginate–Inulin Microbeads as Carriers for Aqueous Carqueja Extract

“…The aqueous extract of carqueja was obtained by boiling a mixture of plant samples and distilled water in a Clevenger apparatus, followed by lyophilization of the aqueous phase as described by Coelho and others (). The appropriate amount of the extract (2 mg/mL) was added to Na–alginate water solution (1.5% w/v) to prepare extract–alginate solution (Manojlovic and others ; Stojanovic and others ). In addition, extract–alginate solution was mixed with 10% and 20% (w/v) of inulin to prepare extract–alginate–inulin solutions.…”

Hybrid Hydrogels with Extremely High Stiffness and Toughness

“…28,29 Both alginates are commercially available (FMC BioPolymer). In an aqueous solution containing both alginates, the viscosity reduces as the fraction of the short-chain alginate increases (Supporting Information, Figure S1).…”