BIOMATERIALS FOR BIOPRINTING - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 125

CHAPTER

6

BIOMATERIALS FOR
BIOPRINTING

Lee Jia Min, Tan Yong Sheng Edgar, Zhu Zicheng and Yeong Wai Yee
School of Mechanical & Aerospace Engineering, Nanyang Technological University, Singapore

6.1 INTRODUCTION
Modern medicine and research rely heavily on biomaterials. Biomaterials are used in small objects,
such as early diagnosis devices and sustained drug release, and in larger objects, such as permanent
implants. In the case of bioprinting, such biomaterials serve as an artificial extracellular matrix (ECM)
for the cells. They provide structural support and enable cellular attachment, help isolate tissues and
cells, and regulate cellular functions and behaviors ( Chan and Leong, 2008 ). For biomaterials to be
considered for bioprinting, they need to possess certain characteristics, just as the process used to fab-
ricate them must meet its own set of requirements.
Hydrogels make up the bulk of ink used in bioprinting. They are generally used as they closely
mimic the natural ECM in our body. Additionally, due to their high water content, hydrogels are able
to protect cells and fragile drugs, such as peptides and proteins. These polymers can be modified with
ligands for better cell adhesion.
This chapter will first discuss the important characteristics of “ink” used in bioprinting. It will
then explore different cross-linking mechanisms of hydrogel and describe examples of hydrogel used
in bioprinting. Finally, potential developments and applications as well as research directions will be
discussed.

6.2 PARAMETERS FOR BIOPRINTING
6.2.1 BIOCOMPATIBILITY
The biocompatibility of biomaterials is the most important prerequisite for their use as a scaffold.
Biomaterials have to support cell attachment, migration, and other basic cellular functions ( Chan and
Leong, 2008 ). Chemicals involved in cross-linking of hydrogels should not affect cell viability ( Bry-
ant, 2008 ). Some photo-initiators and monomers used during cross-linking of hydrogels have been
found to be toxic if left unreacted ( Bryant et al., 2000 ).
To evaluate biocompatibility, live/dead staining is usually employed after 24 h to determine the
cytocompatibility of the hydrogel and cross-linking process used with the cells. The results can
be quantified using a microplate reader to measure the fluorescence intensity through which the