| 1. |
- Shaali, Mehrnaz, 1981, et al.
(författare)
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Site-selective immobilization of functionalized DNA origami on nanopatterned Teflon AF
- 2017
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 5:30, s. 7637-7643
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the use of arrays of Teflon AF nanopillars for directing the assembly of single rectangular DNA origami scaffolds, functionalized with covalently linked fluorophore molecules, in defined positions on patterned surfaces. This is achieved by introducing Teflon AF as a non-amplified negative e-beam resist, which is exposed and chemically developed to generate arrays of hydrophobic nanopillars with a minimum feature size 40 nm. Binding of the DNA origami to the pillars is facilitated by porphyrin moieties that act as hydrophobic molecular anchors, reaching 80% coverage of the available sites. This combination of top-down lithography and bottom-up self assembly is an efficient means of fabricating hierarchically structured bio-nanointerfaces in which the positioning of functional units is precisely controlled on the molecular scale inside the DNA assembly, and on the nanoscale at pre-designed locations on the substrate.
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| 2. |
- Aissaoui, Nesrine, 1983, et al.
(författare)
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FRET enhancement close to gold nanoparticles positioned in DNA origami constructs
- 2017
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Ingår i: Nanoscale. - Cambridge, United Kingdom : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 9:2, s. 673-683
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Tidskriftsartikel (refereegranskat)abstract
- Here we investigate the energy transfer rates of a Förster resonance energy transfer (FRET) pair positioned in close proximity to a 5 nm gold nanoparticle (AuNP) on a DNA origami construct. We study the distance dependence of the FRET rate by varying the location of the donor molecule, D, relative to the AuNP while maintaining a fixed location of the acceptor molecule, A. The presence of the AuNP induces an alteration in the spontaneous emission of the donor (including radiative and non-radiative rates) which is strongly dependent on the distance between the donor and AuNP surface. Simultaneously, the energy transfer rates are enhanced at shorter D-A (and D-AuNP) distances. Overall, in addition to the direct influence of the acceptor and AuNP on the donor decay there is also a significant increase in decay rate not explained by the sum of the two interactions. This leads to enhanced energy transfer between donor and acceptor in the presence of a 5 nm AuNP. We also demonstrate that the transfer rate in the three "particle" geometry (D + A + AuNP) depends approximately linearly on the transfer rate in the donor-AuNP system, suggesting the possibility to control FRET process with electric field induced by 5 nm AuNPs close to the donor fluorophore. It is concluded that DNA origami is a very versatile platform for studying interactions between molecules and plasmonic nanoparticles in general and FRET enhancement in particular.
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| 3. |
- Aissaoui, Nesrine, 1983, et al.
(författare)
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Unravelling surface changes on Cu-Ni alloy upon immersion in aqueous media simulating catalytic activity of aerobic biofilms
- 2020
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 503
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Tidskriftsartikel (refereegranskat)abstract
- Cu-Ni alloys are extensively used in contact with natural waters and are impacted by microbial activities of biofilms. The mechanisms by which surface changes occur upon immersion remain not well understood. Herein, an aerobic microbial activity of natural biofilms is mimicked by the enzymatic generation of an oxidizing agent and an organic acid. Surface changes are probed through a detailed analysis of XPS spectra which allowed a distinction between compounds of organic and inorganic nature to be made. Results show that the surface is composed of copper oxides/hydroxides, presumably Cu2O and Cu(OH)2 and Ni hydroxides. The enzyme-catalyzed reaction causes a significant depletion of Ni and inorganic oxygen, while the concentration of copper, CuI and CuII, varies only slightly. Surface changes concern the organic phase; the amount of organic compounds strikingly increases in the presence of enzymes, and the XPS spectra reveal the accumulation of compounds with high oxidized carbon content, attributed to adsorbed gluconate. Correlations between spectral data suggest the formation of Cu-gluconate complex, probably through coordinative bonds between gluconates and CuII on the oxide layer. These findings are particularly important to properly evaluate the impact of microbial activities on the sustainability of Cu-Ni alloys upon natural exposures.
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