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Nanostructure and biomolecule interactions : Characterizing the complex

Gunnarsson, Stefan LU (2018)
Abstract (Swedish)
Nanostructures are found everywhere in our environment, of either natural or
anthropogenic origin. Volcanoes emit them, breakdown of plastic releases them, and
they are even produced in candlelight. Designed nanostructures are used in sunscreen,
food products, electronics and many more readily available products. Still, there are a
lot of things we do not know about their behavior. To call them miniscule would be
an understatement. Their size is between one and one hundred nanometers. The width
of a human hair is close to the resolution limit of our eyes. Nanostructures are more
than a thousand times smaller. To better emphasize their size, your fingernails grow by
one nanometer every second! But why and how... (More)
Nanostructures are found everywhere in our environment, of either natural or
anthropogenic origin. Volcanoes emit them, breakdown of plastic releases them, and
they are even produced in candlelight. Designed nanostructures are used in sunscreen,
food products, electronics and many more readily available products. Still, there are a
lot of things we do not know about their behavior. To call them miniscule would be
an understatement. Their size is between one and one hundred nanometers. The width
of a human hair is close to the resolution limit of our eyes. Nanostructures are more
than a thousand times smaller. To better emphasize their size, your fingernails grow by
one nanometer every second! But why and how should we investigate them?
When we put a grain of salt in a glass of water, the grain will dissolve into its charged
atoms, or ions. The grain of salt has only disappeared in the sense that our eyes do no
longer detect it. Its ions are floating around in the glass of water. If we want to see
objects smaller than a hair, we need some sort of equipment like a magnifying glass or
a microscope. Doing so, we can see individual cells but we are still quite far from being
able to see the ions. The ions are, after all, among the smallest things there are. As we
know, when we eat too much salt, we feel bloated. This is because the ions are so small
that they can travel more or less anywhere within our bodies and they retain water.
The size of nanostructures is closer to the size of atoms than to the grain of salt. The
smallest nanostructures are only a few atoms in diameter which gives them properties
very different to those of larger objects, for example a grain of sand. Similar to the grain
of sand, many nanostructures do not dissolve easily. What happens when these
nanostructures enter our bodies? There they meet molecules of a similar size – proteins.
Proteins are responsible for most of our bodies’ functions. Everything from our senses
like eyesight and taste, to transport of oxygen and the structure of muscles, from our
immune system to blood clotting. Thousands of different proteins, each with their
unique structure and functions, maintain a properly functioning organism. When
nanostructures and proteins interact, they can bind to each other and form a new
structure with properties that lie between the two individual components. The
nanostructure adsorbs a layer of proteins. This layer can be composed of proteins with
various biological functions. By adsorbing to the nanostructure, the proteins might lose
their structure and function. In order to understand the biological impact of
nanostructures, it is important to know which proteins bind to nanostructures and the
effect it has on the proteins.
Working with structures on this size scale comes with great challenges. In order to
identify proteins bound to the nanostructures, we can isolate them by centrifugation.
Doing so, we can identify single proteins adsorbed to the nanostructure out of a pool
of thousands of proteins found in blood. When we have identified the proteins, we get
clues about which biological mechanisms might affected by the binding. We can detect
this binding by looking at how fast the nanostructure moves in solution. When proteins
bind to it, it will move slower. We can even look at single nanostructures and the
proteins adsorbed to them by using an electron microscope.
When we understand how nanostructures behave in the biological environment, we
can ensure that their design and function is in good agreement with nature and society,
thereby helping fulfil the enormous potential of this rapidly growing technology. (Less)
Abstract
This thesis presents the results of studies done on various biomolecules and their interactions with nanomaterials. The biomolecule sources are everything from purified, single proteins to the complicated mixture of blood serum and cell culture media. Similarly, the nanomaterial sources vary from spherical titanium dioxide, gold, and polystyrene nanoparticles to novel nanowires of gallium arsenide or gallium phosphide. Regardless of the biomolecules or nanomaterials, they interact in ways that require careful characterization in case the environment and organisms are exposed to theses increasingly common materials. The adsorbed protein layer on a nanostructure is called the protein corona and the nanomaterial together with its adsorbed... (More)
This thesis presents the results of studies done on various biomolecules and their interactions with nanomaterials. The biomolecule sources are everything from purified, single proteins to the complicated mixture of blood serum and cell culture media. Similarly, the nanomaterial sources vary from spherical titanium dioxide, gold, and polystyrene nanoparticles to novel nanowires of gallium arsenide or gallium phosphide. Regardless of the biomolecules or nanomaterials, they interact in ways that require careful characterization in case the environment and organisms are exposed to theses increasingly common materials. The adsorbed protein layer on a nanostructure is called the protein corona and the nanomaterial together with its adsorbed biomolecules is called a complex.
We show that when titanium dioxide nanoparticles are mixed with blood serum, a broad range of complex sizes are formed.
Traditionally, the protein corona has been considered homogeneous for specific nanoparticle and serum concentration ratio.
However, our results show that the corona varies with the complexes’ size.
We also look at the effect protein has on very low concentration of 20 nm gold nanoparticles in cell culture medium. Using a
combination of analytical techniques, we show that in protein enriched cell culture medium, the nanoparticles are stable. In cell
culture medium without added protein, the nanoparticles aggregate slowly. We describe the aggregation rate and the aggregate
morphology and identify arginine, an aggregation inducing amino acid in the biomolecular corona.
Furthermore, we study the binding of purified proteins on nanowires by cryo-transmission electron microscopy, X-ray based
analytical techniques, and by changes in the sedimentation rate of nanowires with and without adsorbed protein layer. By rotating
the electron microscope stage during imaging, we can image irregularities in the protein corona formed by the large, cross shaped protein laminin.
Finally, we study the effect of various nanostructures on the activity of the enzyme myeloperoxidase. The nanostructures’ effect
was highly dependent on the complexity of the environment. The effect ranged from almost total inactivation to increasing the
activity up to three-fold. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Höök, Fredrik, Biological Physics, Department of Physics, Chalmers University of Technology, Sweden
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Nanostructures, Proteins, Lipids, Protein corona, Aggregation, Sedimentation, Diffusion, Electron microscopy, Enzyme activity, Nanowires, Nanoparticles
pages
220 pages
publisher
Lund University
defense location
Kemicentrum Lecture Hall B, Naturvetarvägen 14, Lund
defense date
2018-10-10 10:00
ISBN
978-91-7422-592-1
978-91-7422-601-0
language
English
LU publication?
yes
id
b85bcfc0-f650-4d5a-aee0-399192bbf65b
date added to LUP
2018-09-11 10:31:59
date last changed
2018-11-21 21:41:33
@phdthesis{b85bcfc0-f650-4d5a-aee0-399192bbf65b,
  abstract     = {This thesis presents the results of studies done on various biomolecules and their interactions with nanomaterials. The biomolecule sources are everything from purified, single proteins to the complicated mixture of blood serum and cell culture media. Similarly, the nanomaterial sources vary from spherical titanium dioxide, gold, and polystyrene nanoparticles to novel nanowires of gallium arsenide or gallium phosphide. Regardless of the biomolecules or nanomaterials, they interact in ways that require careful characterization in case the environment and organisms are exposed to theses increasingly common materials. The adsorbed protein layer on a nanostructure is called the protein corona and the nanomaterial together with its adsorbed biomolecules is called a complex.<br/>We show that when titanium dioxide nanoparticles are mixed with blood serum, a broad range of complex sizes are formed.<br/>Traditionally, the protein corona has been considered homogeneous for specific nanoparticle and serum concentration ratio.<br/>However, our results show that the corona varies with the complexes’ size.<br/>We also look at the effect protein has on very low concentration of 20 nm gold nanoparticles in cell culture medium. Using a<br/>combination of analytical techniques, we show that in protein enriched cell culture medium, the nanoparticles are stable. In cell<br/>culture medium without added protein, the nanoparticles aggregate slowly. We describe the aggregation rate and the aggregate<br/>morphology and identify arginine, an aggregation inducing amino acid in the biomolecular corona.<br/>Furthermore, we study the binding of purified proteins on nanowires by cryo-transmission electron microscopy, X-ray based<br/>analytical techniques, and by changes in the sedimentation rate of nanowires with and without adsorbed protein layer. By rotating<br/>the electron microscope stage during imaging, we can image irregularities in the protein corona formed by the large, cross shaped protein laminin.<br/>Finally, we study the effect of various nanostructures on the activity of the enzyme myeloperoxidase. The nanostructures’ effect<br/>was highly dependent on the complexity of the environment. The effect ranged from almost total inactivation to increasing the<br/>activity up to three-fold.},
  author       = {Gunnarsson, Stefan},
  isbn         = {978-91-7422-592-1},
  keyword      = {Nanostructures,Proteins,Lipids,Protein corona,Aggregation,Sedimentation,Diffusion,Electron microscopy,Enzyme activity,Nanowires,Nanoparticles},
  language     = {eng},
  pages        = {220},
  publisher    = {Lund University},
  school       = {Lund University},
  title        = {Nanostructure and biomolecule interactions : Characterizing the complex},
  year         = {2018},
}