Modeling the Flow Behavior and Flow Rate of Medium Viscosity Alginate for Scaffold Fabrication With a Three-Dimensional Bioplotter

Abstract

Tissue regeneration with scaffolds has proven promising for the repair of damaged tissues or organs. Dispensing-based printing techniques for scaffold fabrication have drawn considerable attention due to their ability to create complex structures layer-by-layer. When employing such printing techniques, the flow rate of the biomaterial dispensed from the needle tip is critical for creating the intended scaffold structure. The flow rate can be affected by a number of variables including the material flow behavior, temperature, needle geometry, and dispensing pressure. As such, model equations can play a vital role in the prediction and control of the flow rate of the material dispensed, thus facilitating optimal scaffold fabrication. This paper presents the development of a model to represent the flow rate of medium viscosity alginate dispensed for the purpose of scaffold fabrication, by taking into account the shear and slip flow from a tapered needle. Because the fluid flow behavior affects the flow rate, model equations were also developed from regression of experimental data to represent the flow behavior of alginate. The predictions from both the flow behavior equation and flow rate model show close agreement with experimental results. For varying needle diameters and temperatures, the slip effect occurring at the needle wall has a significant effect on the flow rate of alginate during scaffold fabrication.

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

“…The extruded alginate precursor must gel quickly to assist the fabrication process and support cell survival (Tripathi and Mishra, 2012;Yang et al, 2013). In this regard, divalent ionic crosslinkers have frequently been used to crosslink extruded hydrogel-based bioink because the ions cause rapid gelation and the gels can have acceptable printability and support the viability of any incorporated cells (Sarker and Chen, 2017).…”

Modeling of the Mechanical Behavior of 3D Bioplotted Scaffolds Considering the Penetration in Interlocked Strands

“…This asymmetry might cause an increase in the error between predicted and real values because of numerous variables associated with the 3D biofabrication regulate the structural uniformity and geometry of the scaffold. Fluid viscosity, temperature, dispensing pressure, needle speed, and crosslinker concentration have a profound effect on the strand diameter, porosity, and pore size distribution [24]. In this study, the scaffolds were printed in a static volume of the crosslinking solution of 1 mL and 50 mM CaCl 2 , the number of available Ca 2+ ions in the crosslinking media decreases gradually with the fabrication of successive layers.…”

“…Materials utilized in this experiment were alginic acid sodium salt from brown algae (medium viscosity) with P-code 1001172534 and calcium chloride dehydrate with P-code 1001911753 (Sigma-Aldrich Canada Ltd., Toronto, ON, Canada). In addition, a tissue culture plate was treated with 0.5% (w/v) polyethylenimine (PEI, Alfa Aesar, Haverhill, MA, United States, Mw: 60,000) and incubated overnight at 37 • C. This coating can improve the surface adhesion of alginate strands during the printing process to achieve successful printing [24]. To prepare a 3% w/v alginate solution, 7.5 g of alginate powder was weighted using an analytical balance (Sartorius, CP 225 D, Goettingen, Germany), then added to 250 mL distilled water in a beaker covered by a parafilm.…”

Experimental Investigation and Optimal 3D Bioprinting Parameters of SA-Gel Porous Cartilage Scaffold

“…In this study, we attempted to combine gelatin and sodium alginate to obtain a composite sodium alginate and gelatin (SA-GEL) hydrogel, then use 3D printing technology to obtain the cartilage scaffolds with good mechanical strength and biocompatibility. In the printing process of fabricating SA-GEL cartilage scaffolds, the printability was determined by many factors, which mainly include two kinds of factors-parameters of the printing material and parameters of the printing setup [21]. Through reasonable material configuration and optimized machine parameter selection, a cartilage scaffold structure that can meet the requirements of mechanical properties and biocompatibility was fabricated.…”