Page 89 - IJB-3-1

Ratima Suntornnond, Jia An and Chee Kai Chua

Table 1. Common support hydrogels in bioprinting

Support hydrogel Model hydrogel Bioprinted form References
Gelatin and
derivatives Alginate, Fibrin and collagen 3D hollow structure [13]
Agarose GelMA, SPELA*, PEGDMA** and PEGDA 2.5D complex track [14]
Pluronic and derivatives GelMA and Agarose 2.5D complex track and micro-pattern [11,15]
*Star poly(ethylene glycol-co-lactide) acrylate
**Poly(ethylene glycol) dimethacrylate

Figure 2. (A) Computer model of anatomical heart (red arrows pointed the overhanging parts) and (B) Computer model of anatomi-
cal heart with support structure.

hold even in other 3D printing techniques (Figure 2B). out sacrificing cell viability. In order to achieve this
It is almost impossible for bioprinting to fabricate this property, either the concentration of model and sup-
structure without using support. However, comparing port materials need to be similar or there is an interac-
the materials that have been used in Iused deposition tion to create wall between model and support mate-
2+
modelling (FDM) with hydrogels or bioinks for bio- rials. For example, if model material contains Ca
printer, the mechanical strength of the FDM materials and support contains alginate, the wall can be cre-
is typically stronger [4–16] . The current hydrogels that ated by semi physical crosslinked reaction of alginate
have been used with bioprinter are too soft to hold the and calcium ion. All the mentioned techniques need to
shape. Moreover, with the high water content, osmosis involve with the advancement of materials science and
pressure will affect the interaction between model and chemistry to understand the nature of materials and
support materials (e.g. water travels by osmosis pres- reaction mechanism.
sure to another hydrogel which will lead to change in
concentration, viscosity and mechanical properties). 3. Conclusion
Thus, the requirements needed in bioprinting for fa- It is evident that support materials are essential
bricating 3D complex hollow structures are: (i) the for both 3D printing and bioprinting. In 3D printing,
material (including both model and support) must the support materials have been used to fabricate
have sufficient shape integrity and can be printed in a complex structures with high resolution, which
cell friendly environment. To ensure biocompatibility should be applicable to bioprinitng as well. The sup-
properties, the bio-derived materials or even extracel- port materials may also be applied for upscale printing,
lular matrix (ECM) derived materials are preferred. organ printing and the advancement in tissue model
Furthermore, to enhance mechanical properties, str- for drug delivery and other related biomedical appli-
ong bio-derived materials such as silk or hydroxyapa- cations. In terms of achieving 3D complex hollow
tite can be integrated with the model hydrogel as the structures, it is challenging to rely on single material
composite natural materials; (ii) there is no or minimal to accomplish it. The 2.5D complex track by using
reaction between model and support materials; and sacrificial materials has proved its application for
(iii) support materials must be easily removable with- lab-on-a chip and organ-on-a chip level. Nevertheless,

International Journal of Bioprinting (2017)–Volume 3, Issue 1 85