Among various available 3D bioprinting techniques, extrusion-based three-dimensional (3D) bio-printing allows the deposition of cell-laden bio-ink, ensuring predefined scaffold architecture that may offer living tissue regeneration. With a combination of unique characteristics such as biocompatibility, less cell toxicity, and high-water content, natural hydrogels are a great candidate for bio-ink formulation for the extrusion-based 3D bioprinting process. However, due to its low mechanical integrity, hydrogel faces a common challenge in maintaining structural ty. To tackle this challenge, we characterized the rheological properties of a set of hybrid hydrogels composed of cellulose-derived nanofiber (TEMPO-mediated nano-fibrillated cellulose, TONFC), carboxymethyl cellulose (CMC) and commonly used alginate. A total of 46 compositions were prepared using higher (0.5% and 1.0%) and lower percentages (0.005% and 0.01%) of TONFC, 1%–4% of CMC, and 1%–4% of alginate to analyze the rheological properties. The shear thinning coefficients of n and K were determined for each composition from the flow diagram and co-related with the 3D printability. The ability to control rheological properties with various ratios of a nanofiber can help achieve a 3D bio-printed scaffold with defined scaffold architecture.
Tuning Shear Thinning Factors of 3D Bio-Printable Hydrogels Using Short Fiber
Among various available 3D bioprinting techniques, extrusion-based three-dimensional (3D) bioprinting allows the deposition of cell-laden bioink, ensuring predefined scaffold architecture that may offer living tissue regeneration. With a combination of unique characteristics such as biocompatibility, less cell toxicity, and high water content, natural hydrogels are a great candidate for bioink formulation for the extrusion-based 3D bioprinting process. However, due to its low mechanical integrity, hydrogel faces a common challenge in maintaining structural integrity. To tackle this challenge, the rheological properties, specifically the shear thinning behavior (reduction of viscosity with increasing the applied load/shear rate on hydrogels) of a set of hybrid hydrogels composed of cellulose-derived nanofiber (TEMPO-mediated nano-fibrillated cellulose, TO-NFC), carboxymethyl cellulose (CMC), and commonly used alginate, were explored. A total of 46 compositions were prepared using higher (0.5% and 1.0%) and lower percentages (0.005% and 0.01%) of TO-NFC, 1–4% of CMC, and 1–4% of alginate to analyze the shear thinning factors such as the values of n and K, which were determined for each composition from the flow diagram and co-related with the 3D printability. The ability to tune shear thinning factors with various ratios of a nanofiber can help achieve a 3D bio-printed scaffold with defined scaffold architecture.
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- Award ID(s):
- 1757371
- NSF-PAR ID:
- 10399031
- Date Published:
- Journal Name:
- Materials
- Volume:
- 16
- Issue:
- 2
- ISSN:
- 1996-1944
- Page Range / eLocation ID:
- 572
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract -
Babski-Reeves, K ; Eksioglu, B ; Hampton, D. (Ed.)Extrusion-based three-dimensional (3D) bio-printing is one of the several 3D bioprinting methods that is frequently used in current times. This method enables the accurate deposition of cell-laden bio-ink while ensuring a predetermined scaffold architecture that may allow living tissue regeneration. Natural hydrogels are a strong choice for bio-ink formulation for the extrusion-based 3D bioprinting method because they have a combination of unique properties, which include biocompatibility, reduced cell toxicity, and high-water content. However, due to its low mechanical integrity, hydrogel frequently struggles to retain structural stability. To overcome this challenge, we evaluated the rheological characteristics of distinct hybrid hydrogels composed of carboxymethyl cellulose (CMC), a widely used alginate, and nanofibers generated from cellulose (TEMPO-mediated nano-fibrillated cellulose, TONFC). Therefore, to examine the rheological properties, a set of compositions was developed incorporating CMC (1%–4%), alginate (1%–4%), and higher and lower contents of TONFC (0.5%) and (0.005%) respectively. From the flow diagram, the shear thinning coefficients of n and K were calculated, which were later linked to the 3D printability. With the guidance of diverse nanofiber ratios, it is possible to regulate the rheological properties and create 3D bioprinted scaffolds with well-defined scaffold architecture.more » « less
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Abstract Bioprinting for regenerative medicine has been gaining a lot of popularity in today's world. Despite being one of the rigorously studied fields, there are still several challenges yet to be solved. Geometric fidelity and mechanical complexities stand as roadblocks when it comes to the printability of the customized constructs. Exploring the rheological properties of the compositions helps us understand the physical and mechanical properties of the biomaterials which are closely tied to the printability of the filament and eventually, geometric fidelity of the constructs. To ensure the structural integrity of the constructs, viscosity enhancers such as carboxymethyl cellulose (CMC) and crosslinkers like CaCl2 and CaSO4 were used. These crosslinkers can be used before (precrosslinking) and after (postcrosslinking) the extrusion of considered compositions to investigate and compare the outcome. To do this, mixtures of CMC (viscosity enhancer), Alginate, and CaCl2 and CaSO4 (crosslinkers) were prepared at various concentrations maintaining minimum solid content (≤8%). Each composition was subjected to a set of rheological tests like flow curve for shear thinning behavior, three points thixotropic for recovery rate, and amplitude test for gelation point. Various geometric fidelity identification tests were conducted and correlated with their physical properties. Some compositions were used to fabricate large-scale constructs (in cm-scale) to demonstrate their capability. This research is a thorough investigation of compositions when they are introduced to crosslinkers and viscosity enhancers which can be crucial for the 3D printing world.more » « less
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Maintaining shape fidelity of 3D bio-printed scaffolds with soft biomaterials is an ongoing challenge. Here, a rheological investigation focusing on identifying useful physical and mechanical properties directly related to the geometric fidelity of 3D bio-printed scaffolds is presented. To ensure during- and post-printing shape fidelity of the scaffolds, various percentages of Carboxymethyl Cellulose (CMC) (viscosity enhancer) and different calcium salts (CaCl2 and CaSO4, physical cross-linkers) were mixed into alginate before extrusion to realize shape fidelity. The overall solid content of Alginate-Carboxymethyl Cellulose (CMC) was limited to 6%. A set of rheological tests, e.g., flow curves, amplitude tests, and three interval thixotropic tests, were performed to identify and compare the shear-thinning capacity, gelation points, and recovery rate of various compositions. The geometrical fidelity of the fabricated scaffolds was defined by printability and collapse tests. The effect of using multiple cross-linkers simultaneously was assessed. Various large-scale scaffolds were fabricated (up to 5.0 cm) using a pre-crosslinked hybrid. Scaffolds were assessed for the ability to support the growth of Escherichia coli using the Most Probable Number technique to quantify bacteria immediately after inoculation and 24 h later. This pre-crosslinking-based rheological property controlling technique can open a new avenue for 3D bio-fabrication of scaffolds, ensuring proper geometry.more » « less
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Abstract 3D bioprinting improves orientation of
in vitro tumor models by offering layer by layer positioning of cancer cells and cancer associated fibroblasts (CAFs) which can replicate tumor microenvironment. Aim of this study was to develop a sodium alginate -gelatin (SA-GL) hydrogel by optimizing rheological parameters to print non-small cell lung cancer (NSCLC) patient derived xenograft (PDX) cells and lung CAFs co-cultures. SA-GL hydrogels were prepared, and rheological properties were evaluated. Both the cells were mixed with the hydrogel and printed using INKREDIBLE bioprinter. Hydrogels prepared with 3.25% and 3.5% (w/v) SA and 4% (w/v) GL showed higher printability and cell viability. A significant decline in viscosity with shear rate was observed in these hydrogels suggesting the shear thinning property of hydrogels. Spheroid size distribution after 15 days was in the diameter range of 50–1100 µm. Up-regulation of vimentin, α-SMA and loss of E-cadherin in co-culture spheroids confirmed cellular crosstalk. This study demonstrates that rheological optimization of SA-GL hydrogel enhances printability and viability of NSCLC PDX and CAF co-culture which allows 3D co-culture spheroid formation within the printed scaffold. Therefore, this model can be used for studying high throughput drug screening and other pre-clinical applications.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/ma16020572
