Use of the polycation polyethyleneimine to improve the physical properties of alginate–hyaluronic acid hydrogel during fabrication of tissue repair scaffolds

Abstract

Recently alginate-based tissue repair scaffolds fabricated using 3D printing techniques have been extensively examined for use in tissue engineering applications. However, their physical and mechanical properties are unfavorable for many tissue engineering applications because these properties are poorly controlled during the fabrication process. Some improvement of alginate gel properties can be realized by addition of hyaluronic acid (HA), and this may also improve the ability of cells to interact with the gel. Here, we report improvement of the physical properties of alginate-HA gel scaffolds by the addition of the polycation polyethyleneimine (PEI) during the fabrication process in order to stabilize alginate molecular structure through the formation of a polyelectrolyte complex. We find that PEI has a significant beneficial influence on alginate-HA scaffold physical properties, including a reduction in the degree of gel swelling, a reduction in scaffold degradation rate, and an increase in the Young's modulus of the gel. Further study shows that fabrication of alginate-HA gels with PEI increases the encapsulation efficiency of bovine serum albumin, a model protein, and reduces the subsequent initial protein release rate. However, it was also found that survival of Schwann cells or ATDC-5 chondrogenic cells encapsulated during the scaffold fabrication process was modestly reduced with increasing PEI concentration. This study illustrates that the use of PEI during scaffold fabrication by plotting can provide an effective means to control alginate-based scaffold properties for tissue engineering applications, but that the many effects of PEI must be balanced for optimal outcomes in different situations.

Influence of crosslinking on the mechanical behavior of 3D printed alginate scaffolds: Experimental and numerical approaches

“…Calcium chloride dehydrate (Sigma-Aldrich Canada Ltd., P-code 1001911753) was used for the preparation of a 50 mM CaCl2 crosslinking solution. Tissue culture plates were treated with 0.5% (w/v) polyethylenimine (PEI, Alfa Aesar) and then incubated overnight at 37 °C and 5% carbon dioxide to improve the attachment of the first printed layer of alginate to the culture plate during the ensuing scaffold fabrication (Rajaram et al, 2015).…”

“…Over the last decade, several hydrogel precursors have been investigated to develop suitable bioinks for extrusion-based systems (You et al, 2017). Seaweed-derived sodium alginate is a potential bioink for fabricating cell-incorporated 3D structures with remarkable geometric precision (Rajaram et al, 2015). In an extrusion-based biofabrication system, a cell-hydrogel precursor mixture is extruded layer-by-layer through a nozzle as per a pre-designed structure.…”

Indirect 3D bioprinting and characterization of alginate scaffolds for potential nerve tissue engineering applications

“…3D scaffolds were directly printed on a 3D bioplotter (EnvisionTEC, Germany). For this, 12-well plates were coated with polyethyleneimine (PEI) for the purpose of enhancing the attachment of first printing layer to the plate during the printing process (Rajaram et al, 2015) and then the coated plates were placed in an incubator over a day for the subsequent use in scaffold printing. Three hydrogels, comprised of 0.5, 1.5, and 3% alginate, representing low to reasonably high concentrations, were chosen to investigate the mechanical and biological performance of scaffolds fabricated by using a direct printing technique.…”

Advancements in Canadian Biomaterials Research in Neurotraumatic Diagnosis and Therapies

“…Scaffolds with living cells and/or bioactive molecules can be fabricated using 3D bioprinting techniques, where a scaffold is fabricated by laying down threads or fibers of bioink, i.e., the mixture of hydrogel, living cells, and/or bioactive molecules, in a controllable layer-by-layer manner [46]. Specifically, Chen et al have illustrated the feasibility of bioprinting scaffolds from alginate hydrogel or a composite hydrogel mixture of alginate and hyaluronic acid, with both controlled microstructure and controlled distribution of living Schwann cells for use in peripheral nerve repair applications [26,[47][48][49][50][51].…”