3D BIOPRINTING TECHNIQUES - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 64

the structural polymer alongside collagen containing preosteoblast cells. Using the same polymer and
cell-laden hydrogel composite strategy, ( Lee et al., 2014a ) fabricated a viable auricle using PCL for the
structural framework, water-soluble poly-ethylene-glycol (PEG) as a sacrificial material, and chondro-
cytes/ adipocytes differentiated from adipose-derived stromal cells encapsulated in alginate hydrogel
as the biological component. Quantitative analyses showed that the auricular cartilage and earlobe fat
can be regenerated while maintaining their inherent functions in different regions of the same structure
at the same time by printing chondrocytes and adipocytes separately. ( Mannoor et al., 2013 ) fabricated
a bionic ear in the anatomic geometry of a human auricle using silicone as the structural component,
bovine chondrocytes-laden alginate as the biological component, and silver nanoparticles infused sili-
cone for electronics. They were able to demonstrate structural integrity and shape retention, > 90%
viability of the printed chondrocytes, and enhanced auditory sensing for radio frequency reception, all
within a single simultaneously printed 3D construct.
3.3.3 LASER-ASSISTED BIOPRINTING
Laser-assisted bioprinting (LAB) is a set of noncontact direct writing processes that utilize a pulsed laser
beam to deposit biological materials using cells onto a substrate. Three components are central to most
LAB systems—a pulsed laser source, a bioink-coated “ribbon,” and a receiving substrate. Nanosecond
lasers with UV or near UV wavelengths are used as the energy source. The “ribbon” is a glass or quartz
target plate that is transparent to the laser radiation wavelength and has one side coated with a heat-sen-
sitive bioink consisting of cells either adhered to a biological polymer or uniformly encapsulated within
a thin layer of hydrogel. Depending on the optical characteristics of the bioink and the laser wavelength,
the system may also contain a laser-absorbing interlayer between the target plate and the bioink to al-
low viable cell transfer. The receiving substrate positioned below the bioink-coated side of the ribbon
is coated with a biopolymer or cell culture medium to maintain cellular adhesion and sustained growth
after cell transfer from the ribbon. The pulse of laser causes rapid volatilization at the ribbon's plate-
bioink interface and propels a high-speed jet of the cell-laden bioink onto the receiving substrate.
A schematic of the LAB approach is presented in Figure 3.4 . Commonly used LAB processes
based on this fundamental working principle include absorbing film-assisted laser-induced forward
transfer (AFA-LIFT) or biological laser processing (BioLP) ( Hopp et al., 2004; Barron et al., 2005 )
FIGURE 3.4
Laser-assisted bioprinting