NANOTECHNOLOGY: A TOOLKIT FOR CELL BEHAVIOR - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 15

FIGURE 1.7
(A) An MRI image of an osteochondral defect (labeled as red color) in human knee joint. (B) Schematic illustration
of a table top stereolithography 3D bioprinter. (C-E) 3D printed PEG-DA hydrogel scaffolds with varied designs.
(F-G) SEM images of 3D bioprinted PEG-DA scaffolds with hexagonal and square pores; and (H) with nHA
particles for osteochondral regeneration. A color version of this figure can be viewed online.
et al . , 2012 ). This work focused on using two-photon polymerization in proximity to living tissue,
and used a near-infrared 100 fs laser instead of a traditional, generally nonbiocompatible UV la-
ser. With a specially developed photoinitiator customized for near-infrared wavelengths, research-
ers were able to print scaffolds approaching 300 m m 2 . Despite Raimondi and Torgeren's success,
Torgeren also mentioned that the scaffolds were only 280 m m × 280 m m × 225 m m, and Raimondi
mentioned that on average 17 cells were found attached to the scaffolds after 6 days of in vitro
culture. This serves to highlight the inherent limitations of the two-photon approach; particularly,
a small overall scaffold-size that limits the scaffolds dimensions to a few hundred micrometers in
each dimension, far below clinical relevance.
1.3.2.2 3D Printing of Nanomaterial Scaffolds for Tissue Regeneration
Nanomaterials for 3D printing are just now being developed. One nanobiomaterial in use is bacterial
nanocellulose (BNC). BNC is a naturally occurring nanomaterial synthesized by bacteria that has been