| 1. |
- Bjork, Per, et al.
(författare)
-
Oligothiophene Assemblies Defined by DNA Interaction : From Single Chains to Disordered Clusters
- 2009
-
Ingår i: SMALL. - 1613-6810. ; 5:1, s. 96-103
-
Tidskriftsartikel (refereegranskat)abstract
- The organization of conjugated polyelectrolytes (CPEs) interacting with biomolecules sets conditions for the biodetection of biological processes and identity, through the use of optical emission from the CPE. Herein, a well-defined CPE and its binding to DNA is studied. By using dynamic light scattering and circular dichroism spectroscopy, it is shown that the CPE forms a multimolecule ensemble in aqueous solution that is more than doubled it? size when interacting with a small DNA chain, while single chains are evident in ethanol. The related changes in the fluorescence spectra upon polymer aggregation are assigned to oscillator strength redistribution between vibronic transitions in weakly coupled H-aggregates. An enhanced single-molecule spectroscopy technique that allows full control of excitation and emission light polarization is applied to combed and decorated;,DNA chains. It is found that the organization of combed CPE-lambda DNA complexes (when dry on the surface) allows considerable variation of CPE distances and direction relative to the DNA chain. By analysis of the polarization data. energy transfer between the polymer chains in individual complexes is confirmed and their sizes estimated.
|
|
| 2. |
- Björk, Per, et al.
(författare)
-
Single molecular imaging and spectroscopy of conjugated polyelectrolytes decorated on stretched aligned DNA
- 2005
-
Ingår i: Nano Letters. - 1530-6984 (print), 1530-6992 (online). ; 5:10, s. 1948-1953
-
Tidskriftsartikel (refereegranskat)abstract
- DNA is the prototype template for building nanoelectronic devices by self-assembly. The electronic functions are made possible by coordinating electronic polymer chains to DNA. This paper demonstrates two methods for fabrication of aligned and ordered DNA nanowires complexed with conjugated polyelectrolytes (CPEs). The complex can be formed either in solution prior to stretching or after stretching of the bare DNA on a surface. Molecular combing was used to stretch the complexes on surface energy patterned surfaces, and PMMA for the bare DNA. Single molecular spectroscopy, in fluorescence, and microscopy, in atomic force microscopy, give evidence for coordination of the short CPE chains to the aligned DNA.
|
|
| 3. |
- Herland, Anna, et al.
(författare)
-
Alignment of a conjugated polymer onto amyloid-like protein fibrils
- 2007
-
Ingår i: Small. - 1613-6810. ; 3:2, s. 318-325
-
Tidskriftsartikel (refereegranskat)abstract
- The amyloid-like fibril is a biomolecular nanowire template of very high stability. Here we describe the coordination of a conjugated polyelectrolyte, poly(thiophene acetic acid) (PTAA), to bovine insulin fibrils with widths of <10 nm and lengths of up to more than 10 <img src="http://www3.interscience.wiley.com/giflibrary/12/mu.gif" />m. Fibrils complexed with PTAA are aligned on surfaces through molecular combing and transfer printing. Single-molecule spectroscopy techniques are applied to chart spectral variation in the emission of these wires. When these results are combined with analysis of the polarization of the emitted light, we can conclude that the polymer chains are preferentially aligned along the fibrillar axis.
|
|
| 4. |
- Herland, Anna, et al.
(författare)
-
Decoration of amyloid fibrils with luminescent conjugated polymers
- 2008
-
Ingår i: Journal of Materials Chemistry. - 0959-9428. ; 18:1, s. 126-132
-
Tidskriftsartikel (refereegranskat)abstract
- In this work we report the coating of a biological template with a polar, but uncharged, luminescent conjugated polymer, soluble in organic solvents but not in water, to produce a nanowire. Amyloid fibrils from bovine insulin were decorated with an alternating polyfluorene derivative. Decorated fibrils were partially aligned on hydrophobic surfaces as separate and bundled fibrils, by means of molecular combing. The single molecule spectroscopy technique utilizing excitation by rotating linearly polarized light and fluorescence detection through a rotating polarizer showed a high degree of anisotropy of the polymer chains on the individual fibrils. The high degree of polarization indicated highly oriented polymer chains with the preferential orientation of the polymer backbone along the fibrils. The anisotropy ratios are comparable with those of well-oriented polymer chains in films. © The Royal Society of Chemistry.
|
|
