Silk-based Stabilization of Biospecimens
proteomics and genomics research has led to an unprecedented need for storage of
biospecimens. Bodily fluids such as blood, saliva, and urine, contain a wide variety of
compounds which can be quantified as biomarkers for diagnostics. The integrity of these
blood components, and thus quality of information attained from them, rests largely on
the storage conditions from sampli... read moreng to analysis. Typically, preservation of blood
derivatives involves continuous storage at -80°C, a significant economic and
logistical burden especially in situations where refrigeration is a challenge. Despite
this need for low energy stabilization technologies, no readily available system exists
that can provide both complete recovery of entrapped material and protection from
storage stresses. Many materials and technologies have been studied for this purpose,
but thus far, none have been able to meet the criteria necessary to maintain the
integrity of the entrapped biomacromolecules. The factors that mainly contribute to the
scarcity of such products include i) protein instability and ii) protein incompatibility
with carrier matrix processing. Studies have suggested, however, that mildly and
aqueously processed silk matrices possess material properties that can stabilize against
a wide range of stresses. Furthermore, the unique structure of silk allows for many
controllable material features that can be used to finely tune the interactions between
silk and entrapped analyte for both release behavior and stability. Therefore, a
three-pronged approach is described herein to fabricate an air dried silk-based
stabilization matrix. First, a silk-based platform that maximizes recovery of a broad
range of biomarkers in blood without compromising downstream analytics was designed with
film thickness and silk molecular weight identified as major players in enhancing
recovery. Physical and chemical interactions that govern the ability to be recover
analytes after encapsulation in silk were also probed and ameliorated. Second, the
stabilizing ability of the developed silk constructs on various biospecimens is assessed
after long-term storage at challenging conditions. Third, the fundamental mechanism by
which silk stabilizes biospecimen components in solid constructs were defined and
applied to silk matrices, where secondary relaxations of the silk material appear key in
predicting stabilizing ability.
Thesis (Ph.D.)--Tufts University, 2016.
Submitted to the Dept. of Chemical and Biological Engineering.
Advisor: David Kaplan.
Committee: Fiorenzo Omenetto, Ayse Asatekin, and Marcus Cicerone.
Keywords: Chemical engineering, and Biomedical engineering.read less