Masters Theses

Abstract

"The purpose of this thesis was to study the rate and extent of aggregation of human and bovine insulin in bulk and in the presence of either polystyrene microspheres with different surface chemistries or liposomes of different composition. Insulin aggregation was followed by turbidimetry, Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering. The Congo red assay was used to corroborate the presence of amyloid deposits and transmission electron microscopy (TEM) was used to analyze the morphology of the amyloid deposits. Our results show that not all the surfaces shortened the lag time. On the other hand, most surfaces had an impact (either significant or minute) on the growth rate of both insulins. Faster nucleation was observed at all times for both insulins when incubated at 60 ºC vs. 37 ºC, 230 rpm. Furthermore, considerable secondary structure changes (from random coils and α-helices to ß sheets and turns) in both insulins during fibrillation were observed. Both, human and bovine insulin exhibited analogous fibril morphologies (i.e. similar length, width, and structure) when treated under the same conditions in the presence and in the absence of surfaces with the exception of incubation at 37 ºC, 230 rpm stirring for 55 hours. In addition, when human and bovine insulin were subjected to mechanical stresses the fibrils appear "fragmented" and hence their size is smaller when compared to insulin that has not been agitated. Bovine insulin fibrils are longer and thinner under these incubation conditions (37 ºC, 230 rpm) than human insulin fibrils. Incubation temperatures were different between agitated insulin (37 ºC) and non-agitated insulin (60 ºC). It is also noticeable that at 60 ºC larger fibrils formed at longer incubation times, for both insulins. The width of the fibrils ranged between 10 to 20 nm, there is not a noticeable dependence/correlation between fibril length and width for human or bovine insulin. On the other hand, based on the obtained images, the statistical analysis, and in agreement with literature the incubation methods utilized determined the fibril morphologies"--Abstract, page iii.

Advisor(s)

Forciniti, Daniel

Committee Member(s)

Ludlow, Douglas K.
Neogi, P. (Partho), 1951-

Department(s)

Chemical and Biochemical Engineering

Degree Name

M.S. in Chemical Engineering

Sponsor(s)

National Science Foundation (U.S.)

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2013

Pagination

xi, 148 pages

Note about bibliography

Includes bibliographical references (pages 183-184).

Rights

© 2013 Paulina Barranco Morales, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Insulin -- Testing
Insulin -- Pharmacokinetics
Solid-liquid interfaces
Amyloid beta-protein

Thesis Number

T 10383

Electronic OCLC #

870651119

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