Page 158 - IJB-9-1

International Journal of Bioprinting Bio-inks for 3D printing cell microenvironment

Table 2. Stiffness values of bio-inks at different scales
Material Modulus Modulus value Dimension Test mode Condition Concentration (w/w) Refs.
MW
PEGDA E 6.5–30 MPa Nanoscale AFM 700 Da * [97]
E 36 kPa Macroscale Compression 2000 Da 15.0% [98]
G 10 kPa Macroscale Compression 2000 Da 15.0%
E 200–400 kPa Macroscale Tension 3000 Da 20.0% [99]
E 40 kPa Macroscale Tension 6000 Da 5.0% [100]
E 200 kPa Macroscale Tension 6000 Da 10.0%
E 320 kPa Macroscale Tension 6000 Da 15.0%
E 430 kPa Macroscale Tension 6000 Da 20.0%
Temperature
GelMA E 133 kPa Nanoscale AFM 25° 10.0% [101]
E 171 kPa Nanoscale AFM 25° 20.0%
E 2.86 ± 0.1 kPa Macroscale Compression 25° 5.0% [102]
E 2.41 ± 0.38 kPa Macroscale Compression 37° 5.0%
E 288.24 ± 62.34 kPa Macroscale Compression 25° 30.0%
E 216.81 ± 10.28 kPa Macroscale Compression 37° 30.0%
E 2.08 ± 0.43 kPa Macroscale Tension 25° 5.0%
E 1.67 ± 0.56 kPa Macroscale Tension 37° 5.0%
E 264.74 ± 11.08 kPa Macroscale Tension 25° 30.0%
E 226.80 ± 39.97 kPa Macroscale Tension 37° 30.0%
Agarose E 168 kPa Nanoscale AFM 25° 1.00% [101]
E 230 kPa Nanoscale AFM 25° 2.00%
Alginate G 0.203 ± 0.013 kPa Macroscale Compression 20° 0.70% [103]
G 1.300 ± 0.129 kPa Macroscale Compression 20° 1.50%
G 3.010 ± 0.084 kPa Macroscale Compression 20° 3.00%
Collagen (Type I) E ~200 Pa Nanoscale AFM 20° 0.20% [104]
E ~500 Pa Nanoscale AFM 20° 0.30%
E ~800 Pa Nanoscale AFM 20° 0.40%
Abbreviations: AFM, atomic force microscopy; E, elasticity modulus; G, shear modulus; MW, molecular weight. *Poly(ethylene glycol) diacrylate
(PEGDA) of this molecular weight is liquid.

suitable gel stiffness are used in stereolithography. There examples of synthetic bio-inks. Natural and synthetic
is no complete division of the materials used in these two materials can complement each other, with no clear-cut
bioprinting methods. Poly (ethylene glycol) diacrylate and advantages or disadvantages. The main skeletons of natural
gelatin methacryloyl (GelMA), for example, are competent inks often contain reactive groups, such as hydroxyl and
for both fabrication methods. amino groups, making them easily chemically modifiable.
Synthetic inks, on the other hand, have a more controllable
Bio-inks can be divided into two types according to
the source: natural and synthetic bio-inks. Alginate (from structure and can be programmed to form more complex
materials (e.g., star-shaped PEG polymers) .
[59]
brown algae), agarose (from red algae), chitosan (from
shrimp shells), silk fibroin (from silk), gellan gum (from Natural hydrogel sources are not always more
microbial fermentation), cellulose (from plant stalks), biocompatible than synthetic ones; in fact, animal protein
collagen (from animal tendon), gelatin (from collagen), sources and species-antigen relationships are important
fibrin/fibrinogen (from plasma), hyaluronic acid (from factors in determining biocompatibility. Alginates from
cartilage), and mixed components of decellularized ECM nature, for example, do not always have better performance
are some of the major natural inks. Polymer macromolecules than synthetic hydrogels at cell adhesion, and in order
such as PEG, pluronic, and polyacrylamide (PAAm) are to be suitable for cell spreading, both require covalent

Volume 9 Issue 1 (2023) 150 https://doi.org/10.18063/ijb.v9i1.632