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@PHDTHESIS{Duznovic:238311,
author = {Duznovic, Ivana},
title = {{I}on-conducting {N}anopores in {P}olymer {M}embranes for
({B}io){M}olecular {S}ensory {A}pplications},
school = {Technische Universität Darmstadt},
type = {Dissertation},
address = {Darmstadt},
publisher = {Technische Universität Darmstadt},
reportid = {GSI-2021-00800},
pages = {XVIII, 179 Seiten},
year = {2021},
note = {Dissertation, Technische Universität Darmstadt, 2020},
abstract = {In the recent years, track-etched nanopores became the
major impulse in the development of nanofluidic biosensing
devices. The fabrication is processed first by bombarding
polymeric films with swift heavy ions. Subsequently, damaged
zones within the polymer membrane are created, which are
transformed into nanopores via chemical etching technique.
Here, pore geometry and diameter are controlled by selecting
a suitable chemical etchant and track-etching conditions.
As-prepared nanopores are cation selective due to the
presence of the ionized carboxylic acid moieties under
physiological conditions, which are generated as a
consequence of the ion-track etching process. The fixed
surface charge polarity and concomitant ion-selectivity of
nanopores is tuneable by the modification of native
carboxylic acid groups. Moreover, these groups are used to
attach desired receptors for biorecognition purpose through
specific ligand-receptor interactions. Surface modification
and biorecognition processes are monitored by measuring the
changes in the electric response of the nanopore via
current-voltage (IV) experiments. Regarding the design and
miniaturization of nanopore-based biosensing devices, this
thesis focusses on the three major challenges, which must be
taken into account to enable applications in real systems:
i) investigating the application of commercially available
nanopore membranes and biodegradable membranes as
alternative substrates for nanofluidic sensors. ii)
Examining innovative receptor-analyte moieties towards their
sensitive, selective and reproducible sensing performance.
Here, a variety of receptors and analytes are investigated
regarding the detection of metal cations, small molecules
(histamine) and biomacromolecules (proteins) as well as
polyelectrolytes. In case of metal cations, the selective
recognition of potassium ion is achieved by immobilizing
pseudo-crown ether-moieties on the pore surface. Moreover,
ultrasensitive subnanomolar Cu(II)-detection is obtained by
decorating nanopores with an amino-terminated copper and
nickel (ATCUN) motif. Both metal cations play crucial roles
within neuronal systems of living organisms. Hence,
monitoring of ion level is beneficial regarding diagnostic
applications. Further inflammatory indicators like histamine
are also successfully detected by the use of nanopore
membranes functionalized with Ni(II)-nitrilotriacetic acid
(NTA)-complexes. In Addition, LBL-deposition is achieved
inside nanopores through the electrostatic attraction
between poly(allylamine hydrochloride) and poly(acrylic
acid) with poly(4-vinylpyridine) (PVP) as a hydrogen-bond
compound. After the cross-linking of stacked
polyelectrolytes, the exposure to basic pH-conditions
triggered the PVP-release, leading to the formation of
porous networks in the nanopores as observed by changes in
the electrical readout and an increased mass transport
across the membrane. This represents the proof of concept
for the stimulated release of drugs. Moreover, the highly
selective and sensitive performance of pore-bounded camellia
nanobody-protein is successfully investigated, which are
single domain antibodies and, therefore, considered as
highly efficient detectors within immune systems. The used
nanobodies exhibit high affinity towards fluorescent
proteins (GFP and mCherry) as evidenced by IV-changes of
modified pore membranes and by CLSM-imaging methods. This
study demonstrates novel analyte detection using nanobody as
receptors on nanopore surfaces and to date receptor-analyte
interactions were performed in macro-sized setup, whose
implantation in real system is quite challenging due to
their sampling volumes of about 7 mL. Therefore, nanoporous
membranes were integrated in miniaturized Lab-on-Chips to
investigate the modification and sensing performance.
Further, the standard aqueous electrolyte used for
IV-measurements is exchanged by human serum to investigate
the IV-impact of a more complex medium on receptor-analyte
interactions across nanopore membranes.},
cin = {MAT},
cid = {I:(DE-Ds200)MAT-20051214OR025},
pnm = {6G15 - GSI-MML Ion Facilities (POF4-6G15) / FAIR Phase-0 -
FAIR Phase-0 Research Program (GSI-FAIR-Phase-0) / HGS-HIRe
- HGS-HIRe for FAIR (HGS-HIRe)},
pid = {G:(DE-HGF)POF4-6G15 / G:(Ds200)GSI-FAIR-Phase-0 /
G:(DE-Ds200)HGS-HIRe},
experiment = {$EXP:(DE-Ds200)UMat_M1;M2;M3-20200803$},
typ = {PUB:(DE-HGF)11},
urn = { urn:nbn:de:tuda-tuprints-140701},
doi = {10.26083/TUPRINTS-00014070},
url = {https://repository.gsi.de/record/238311},
}