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| Home > Publications database > DNA-capped silver nanoparticles for stochastic nanoparticle impact electrochemisty |
| Book/Dissertation / PhD Thesis | FZJ-2021-01631 |
2021
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-541-3
Please use a persistent id in citations: http://hdl.handle.net/2128/27731 urn:nbn:de:0001-2021052727
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.
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