3D Printed Silk Scaffolds with Riboflavin-Induced Light Curing
Abstract: 3D printing
opens up new possibilities and techniques for individualized medicine but it also comes
with inherent weaknesses. One of these drawbacks is the mechanical weakness of the
structures as a result of their laminar construction. This work describes a new printing
system for silk hydrogels that are stiffer than any that have been printed before,
paving the way for taller ... read morestructures that have smaller features. As part of this
printing system, a larger printer was designed with self-contained sterility systems and
a greatly increased print volume compared to current models. Additionally, light-curable
inks were formulated, tested, and printed using existing 3D printers to quantify their
usefulness as part of a catalogue of silk-based hydrogel inks. The long-term goal for
this catalogue is to document formulae and procedures that produce hydrogels of varying
mechanical and biological properties for tissue engineering. The experimental procedures
presented here indicate that modest amounts of physiologically inert light are
sufficient to significantly increase the stiffness of riboflavin-infused silk hydrogels.
In one experiment, approximately 750J of blue light increased the young's modulus of
gels by 50% from 5kPa to 7.5kPa. In a printed tower test, 5J of violet light increased
the modulus of plastic deformation by 13% from 15kPa to 17kPa. Single filaments made
from printed hydrogels treated with focused laser light at levels below 10mJ showed no
significant increase in tensile strength, suggesting that the minimum threshold for
noticeable effects in 2mM riboflavin gels is on the order of magnitude of 1-5J of light.
Applying more than 1,000J of light was not found to increase the stiffness of these
gels. Lastly, the current uses and the future of this technology are
Thesis (M.S.)--Tufts University, 2016.
Submitted to the Dept. of Biomedical Engineering.
Advisor: Fiorenzo Omenetto.
Committee: David Kaplan, Fiorenzo Omenetto, and Gary Leisk.
Keyword: Biomedical engineering.read less