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@PHDTHESIS{Nrbel:891635,
author = {Nörbel, Lena},
title = {{DNA}-capped silver nanoparticles for stochastic
nanoparticle impact electrochemisty},
volume = {66},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2021-01631},
isbn = {978-3-95806-541-3},
series = {Schriften des Forschungszentrums Jülich Reihe Information
/ Information},
pages = {VI, 142},
year = {2021},
note = {Dissertation, RWTH Aachen University, 2021},
abstract = {One of the major challenges in analytical chemistry is
reducing the detection limit of an analytedown to a level
where the specific identification of a single entity is
possible. In thiscontext, nano-impact electrochemistry is
one of the most active and promising research areasin the
field of single-entity experiments. This method is a
versatile analytical procedurefor characterization and
real-time monitoring of bioconjugation and biomolecular
recognitionevents as well as for ultrasensitive detection of
a variety of biological species. The combinationof a highly
sensitive amplifier system and high-density microelectrode
arrays allows detectionof single silver nanoparticle impacts
down to subpicomolar concentrations. For the
analytedetection, silver nanoparticles are modied with
biomolecular receptors alternating their impactfrequency on
the electrode surface. Thus, the particles serve as redox
tags convertingan otherwise redox-inactive target into an
electrochemically detectable species. In this work,silver
nanoparticles were modied with thiolated single stranded
oligonucleotides with varyingmolar ratios of DNA to
nanoparticles. The modified conjugation protocol resulted in
stableDNA-nanoparticle conjugates. In depth characterization
of these conjugates gave insight intotheir structural and
physicochemical properties. In a next step, the impact
behaviour of DNAcappednanoparticles was evaluated and
compared to citrate-capped nanoparticles.
Differentparameters were identified to inuence the impact
probability. First, the surface modicationresults in a
higher nanoparticle stability by preventing particle
aggregation, which increasesthe impact frequency, especially
in the presence of high salt concentrations. Second, the
redoxactivity is reduced in comparison to citrate stabilized
particles. In particular, the ligand surfacedensity as well
as the conformation and size of the receptor molecule were
found to play acrucial role. Furthermore, the composition of
the electrolyte and the applied potential affectthe impact
probability, but to a different extent as for citrate
stabilized particles. By carefullyadjusting the surface
density of ligands, a high particle stability is achieved
while maintainingtheir desired redox activity. The results
demonstrate that DNA-AgNPs possess impactcharacteristics
different from standard citrate stabilized particles. In a
last step, stochasticnanoparticle impact electrochemistry
was probed for the detection of DNA hybridizationevents on
the nanoparticle surface. The results disclose decreased
hybridization eficiencies onthe nanoparticle surface and
reveal that a surface-bound process is more complicated
whencompared to hybridization in solution.},
cin = {IBI-3},
cid = {I:(DE-Juel1)IBI-3-20200312},
pnm = {524 - Molecular and Cellular Information Processing
(POF4-524)},
pid = {G:(DE-HGF)POF4-524},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
urn = {urn:nbn:de:0001-2021052727},
url = {https://juser.fz-juelich.de/record/891635},
}