Synthetic polymers, such as poly(ethylene
glycol diacrylate) (PEGDA),
may make hydrogels more quickly and efficiently; however, these systems
are devoid of cell adhesion ligands. As a result, poly(ethylene glycol)-based
polymers are restricted in their application to tissue engineering,
whereas keratins, a biopolymer functional to the body, have been added
to the PEGDA composite hydrogel to make it further applicable. However,
as keratin is a mixture of proteins, a keratin-based material may
have inconsistent properties due to the complicated keratin composition.
This study investigates the effects of different fractions of keratin
on the keratin/PEGDA composite properties. A hair was extracted and
purified to identify internal keratin filaments (KIFs) and keratin-associated
proteins (KAPs). The KIFs and KAPs were mixed with PEGDA to form a
hydrogel by photo-cross-linking. The porosity measured in the gels
was between 54% and 83%. We also determined the mechanical behavior
of the composite through compression and tension tests. These analyses
yielded a range of material strengths from 4.0 to 7.1 kPa and from
2.7 to 2.3 kPa, respectively. The gel properties correlated highly
with the KAPs/KIFs content, as the two proteins have distinct beta
structures. Modulating this ratio results in a keratin/PEGDA composite
with more controllable gel properties.