Electrochemical catch-and-release of biomolecules for development of new bioelectronic devices
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Typ
Examensarbete för masterexamen
Program
Materials chemistry (MPMCN), MSc
Publicerad
2022
Författare
Cindric, Filip
Jacobsson Krstovic, Oliver
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Purification is a key step when producing pharmaceuticals. A possible alternative to
today’s techniques, is by utilising weak polyelectrolyte brushes on an electrode surface.
These have been proven successful regarding capture and on-demand release
of biomolecules using electrochemistry. However, it has been difficult to achieve this
at physiological pH. The reason is the repulsion that occurs between the brushes
and the biomolecules. In this study, the brushes used are PAA and are negatively
charged at physiological pH. Also, many biomolecules have low isoelectric points,
making them negatively charged as well.
Two strategies will be evaluated to overcome the issue with capture and release at
physiological pH. The first involves the polymer poly(L)lysine (PLL). PLL is cationic
at physiological pH and is therefore expected to have an electrostatic attraction to
the anionic brushes. Furthermore, it is possible to end-couple PLL in order to conjugate
to the biomolecule of interest. The second strategy tests self-manufactured
liposomes, where three different lipids will be tested. These are the zwitterionic
lipid DPPC and the cationic lipids DOTAP and MVL5. The idea is that the formed
cationic liposomes will electrostatically attract to the anionic brushes.
The capture and release of PLL was successful. Also, it is proved that lower molecular
weight PLL is more suitable for the purpose than higher molecular weight PLL.
Applied electrical potentials managed to partly release the PLL but to achieve complete
release, a pH 2 solution was injected. At this state, the pH is far below pKa of
the brushes and the electrostatic attraction is removed. For the second strategy, immobilisation
was more challenging. Different liposome compositions were created,
but only one managed to interact with the brushes at physiological pH. Furthermore,
the release was incomplete even when different pH solutions were injected.
The conclusion is that both of the strategies are worth to consider. However, further
development is required to ensure capture and later release with electrochemistry,
especially with the second strategy involving liposomes.
Beskrivning
Ämne/nyckelord
polyelectrolyte brushes , electrochemistry , poly(L)lysine , liposomes , electrostatic attraction.