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Volume 4
Trends in Green Chemistry
ISSN: 2471-9889
Page 88
JOINT EVENT
Environmental Chemistry 2018 &
Green Technologies 2018
September 20-22, 2018
September 20-22, 2018 Berlin, Germany
&
7
th
Edition of International Conference on
Green Energy, Green Engineering and Technology
8
th
International Conference on
Environmental Chemistry and Engineering
Synthesis of photo-polymerizable keratin from bird feather
Esmaiel Jabbari
University of South Carolina, USA
Statement of the Problem:
Keratin is a family of fibrous proteins found in nature as the major component of wool, hair,
horn, nail and hoof of mammals and birds feather. The disulfide crosslinks in combination with other structural features
like crystallinity and physical interaction between the β-sheets impart high strength to feather. Due to its high strength and
biocompatibility, membranes, sponges and fiber meshes have been produced from keratin. In this work, we describe the
synthesis of a photo-polymerizable hydrogel for cell encapsulation based on the keratin extracted from barbs and barbules of
chicken feather. The novelty is the synthesis of keratin allyl thioether macromer (KeratATE), based on the keratin extracted
from feather that can be dissolved in aqueous cell suspension, injected, and photo-polymerized to generate hydrogels for
surface coating and medical applications. Since keratin is rich in cysteine residues, s-allyl modification of sulfhydryl groups was
used to functionalize keratin for chemical crosslinking.
Methodology:
Keratin was extracted from feather barbs by reducing the disulfide bonds in cysteine residues to sulfhydryl
groups (-SH) (Figure). Next, the free thiol groups were converted to dehydroalanine (Dha) by oxidative elimination using O-(2,
4, 6-Trimethylbenzenesulfonyl) hydroxylamine. Then, the Dha moieties were converted to s-allyl cysteine by reaction with allyl
mercaptan to produce keratin allyl thioether (KeratATE) biopolymer. Conversion of allyl mercaptan before and after allylation
reaction was quantified by 5, 5'dithiobis (2nitrobenzoic acid) (DTNB) test. The secondary structure of the extracted keratin
before and after allylation was determined by circular dichroism and infrared spectroscopy. Molecular weight and purity of
the extracted keratin was measured by gel electrophoresis and dialysis. Crosslinking kinetics and gelation point of KeratATE
was measured by rheometry. Degradation of the crosslinked keratin was measured in aqueous solution supplemented with
collagenase or trypsin.
Findings:
The freeze-dried photo-crosslinked KeratATE hydrogels had a porous, interconnected, honeycomb microstructure.
The compressive modulus of the hydrogels ranged from 1 to 8 kPa depending on KeratATE concentration. Degradation of
KeratATE hydrogel was strongly dependent on trypsin concentration but independent of collagenase.
Conclusion:
Keratin allyl thioether derived from feather is a viable alternative to collagen based biopolymers as a photo-
polymerizable gel with controllable degradation for medical applications.
jabbari@mailbox.scs.eduTrends in Green chem 2018, Volume 4
DOI: 10.21767/2471-9889-C2-012