Sequence-structure-property relationships of recombinant spider silk block copolymers.
Tarakkad Krishnaji, Sreevidhya.
Abstract: Spider silks exist in Nature as block copolymers, where hydrophobic
and hydrophilic regions are linked forming natural biopolymers that organize into
functional materials with exceptional properties. The resemblance of silk to synthetic
polymer systems allowed the design and synthesis of silk-inspired block copolymers. The
main goal was to provide fundamental insight into relationships ... read morebetween peptide primary
sequence, block composition, and block length and observe morphological and structural
features, as a route to understand structure-property relationships with bioengineered
spider silk block copolymers. Assembly was studied at the air-water interface using the
Langmuir Blodgett technique. 2D film assembly was further used to determine assembled
morphologies with varying lengths of hydrophobic blocks. To more fully understand the role
of specific chemical domains responsible for the material features, selective regions were
utilized in peptide formats. The self-assembly features of a spider-silk variant, in
combination with environmental factors was utilized to gain insight into how to tune the
protein designs to direct the process towards specific types of material morphologies.
Tailored materials with tunable functional properties are desirable for many applications
ranging from biomaterials design and drug delivery to high performance structures for use
in engineering. To improve predictability of materials function, multiple parameters in
polymer design need to be considered, along with appropriate models to engineer tailored
material solutions. In collaboration with other labs, a trinity approach was employed where
the combination of controlled synthesis (genetically programmed), tailorable processing
(via microfluidic focusing and film assembly) and molecular modeling were used to enable
prediction of material properties. This approach offers a robust discovery path when
looking towards next generation approaches to targeted functional materials outcomes. In
the second part of the studies, new modes were explored, building off of block copolymer
silk designs above, to target the recovery of heavy metals, with a goal towards needs in
the field of remediation. A chimeric spider silk protein fused with uranium recognition
motifs, was designed, cloned and expressed to generate new proteins that exploit the
benefits of each component, but in a versatile materials-related format. These new proteins
may find utility in chelation therapies to treat exposures to heavy metals, for
environmental recovery operations including monitoring, nuclear waste management,
developmental biology and clinical toxicology.
Thesis (Ph.D.)--Tufts University, 2012.
Submitted to the Dept. of Chemistry.
Advisor: David Kaplan.
Committee: Krishna Kumar, Elena Rybak-Akimova, and Markus Buehler.
Keywords: Chemistry, Biomedical engineering, and Physical chemistry.read less