| 1. |
- Bano, Fouzia, et al.
(författare)
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Toward multiprotein nanoarrays using nanografting and DNA directed immobilization of proteins
- 2009
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:7, s. 2614-2618
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Tidskriftsartikel (refereegranskat)abstract
- Atomic force microscopy nanografting was utilized to prepare DNA nanopatches of different sizes (200 × 200 to 1000 × 1000 nm2) onto which DNA−protein conjugates can be anchored through DNA-directed immobilization. Height measurements were used to assess the binding of the proteins as well as their subsequent interaction with other components, such as antibodies. The results indicate that nanografted patch arrays are well suited for application in biosensing and could enable the fabrication of multifeature protein nanoarrays.
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| 2. |
- Bosco, Alessandro, et al.
(författare)
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Hybridization in nanostructured DNA monolayers probed by AFM : theory versus experiment
- 2012
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 4:5, s. 1734-1741
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Tidskriftsartikel (refereegranskat)abstract
- Nanografted monolayers (NAMs) of DNA show novel physico-chemical properties that make them ideally suited for advanced biosensing applications. In comparison with alternative solid-phase techniques for diagnostic DNA detection, NAMs have the advantage of combining a small size with a high homogeneity of the DNA surface coverage. These two properties favour the extreme miniaturization and ultrasensitivity in high-throughput biosensing devices. The systematic use of NAMs for quantitative DNA (and protein) detection has so far suffered from the lack of a control on key fabrication parameters, such as the ss- or ds-DNA surface coverage. Here we report on a combined experimental–computational study that allows us to estimate the surface density of the grafted DNA by analyzing the sample mechanical response, that is the DNA patch height vs. applied tip load curves. It is shown that the same analysis scheme can be used to detect the occurrence of hybridization with complementary strands in solution and estimate its efficiency. Thanks to these quantitative relationships it is possible to use a single AFM-based setup to: (i) fabricate a DNA NAM, (ii) control the DNA surface coverage, and (iii) characterize its level of hybridization helping the design of NAMs with pre-determined fabrication parameters.
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| 3. |
- Castronovo, Matteo, et al.
(författare)
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Mechanical stabilization effect of water on a membrane-like system
- 2007
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 129:9, s. 2636-2641
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Tidskriftsartikel (refereegranskat)abstract
- The penetration resistance of a prototypical model-membrane system (HS−(CH2)11−OH self-assembled monolayer (SAM) on Au(111)) to the tip of an atomic force microscope (AFM) is investigated in the presence of different solvents. The compressibility (i.e., height vs tip load) of the HS−(CH2)11−OH SAM is studied differentially, with respect to a reference structure. The reference consists of hydrophobic alkylthiol molecules (HS−(CH2)17−CH3) embedded as nanosized patches into the hydrophilic SAM by nanografting, an AFM-assisted nanolithography technique. We find that the penetration resistance of the hydrophilic SAM depends on the nature of the solvent and is much higher in the presence of water than in 2-butanol. In contrast, no solvent-dependent effect is observed in the case of hydrophobic SAMs. We argue that the mechanical resistance of the hydroxyl-terminated SAM is a consequence of the structural order of the solvent−SAM interface, as suggested by our molecular dynamics simulations. The simulations show that in the presence of 2-butanol the polar head groups of the HS−(CH2)11−OH SAM, which bind only weakly to the solvent molecules, try to bind to each other, disrupting the local order at the interface. On the contrary, in the presence of water the polar head groups bind preferentially to the solvent that, in turn, mediates the release of the surface strain, leading to a more ordered interface. We suggest that the mechanical stabilization effect induced by water may be responsible for the stability of even more complex, real membrane systems.
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| 4. |
- Herrero, M. Antonia, et al.
(författare)
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Synthesis and characterization of a carbon nanotube−dendron series for efficient sirna delivery
- 2009
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 131:28, s. 9843-9848
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Tidskriftsartikel (refereegranskat)abstract
- A new series of dendron-functionalized multiwalled carbon nanotube (MWNT) derivatives, characterized by the presence of numerous positively charged tetraalkyl ammonium salts at the periphery of the dendron, has been synthesized. The positive charges on the MWNT surface, coupled with the unique ability of carbon nanotubes (CNTs) to penetrate cell membranes, make the new derivatives potentially ideal vectors for siRNA delivery. Using a fluorescently labeled, noncoding siRNA sequence, we demonstrate that cytoplasmic delivery of the nucleic acid is remarkably increased throughout the different dendron generations. The work reported here highlights the fact that dendron-functionalized CNTs can be rationally designed as efficient carriers of siRNA that can eventually lead to gene silencing.
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| 5. |
- Mirmomtaz, Elham, et al.
(författare)
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Quantitative study of the effect of coverage on the hybridization efficiency of surface-bound DNA nanostructures
- 2008
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 8:12, s. 4134-4139
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that, contrary to current understanding, the density of probe molecules is not responsible for the lack of hybridization in high density single-stranded DNA (ss-DNA) self-assembled monolayers (SAMs). To this end, we use nanografting to fabricate well packed ss-DNA nanopatches within a “carpet matrix” SAM of inert thiols on gold surfaces. The DNA surface density is varied by changing the “writing” parameters, for example, tip speed, and number of scan lines. Since ss-DNA is 50 times more flexible than ds-DNA, hybridization leads to a transition to a “standing up” phase. Therefore, accurate height and compressibility measurements of the nanopatches before and after hybridization allow reliable, sensitive, and label-free detection of hybridization. Side-by-side comparison of self-assembled and nanografted DNA-monolayers shows that the latter, while denser than the former, display higher hybridization efficiencies.
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