Simultaneous imaging of the structure and fluorescence of a supramolecular nanostructure formed by the coupling of π‐conjugated polymer chains in the intermolecular interaction

Shinohara, Ken‐ichi; Suzuki, Tasuku; Kitami, Takeshi

doi:10.1002/pola.21175

Cited by 24 publications

(12 citation statements)

References 15 publications

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“…A probe-scan-type atomic force microscope (AFM) (5500AFM, Agilent Technologies, Santa Clara, CA, USA) was used for molecular imaging in the dynamic (tapping) mode with a cantilever (OMCL-AC240TS, Olympus, Tokyo, Japan) having a spring constant of 1.7 N m − 1 and resonance frequency of 70 kHz (typical values). 26 The set point was optimized for the gentle-touch imaging. A specimen for AFM imaging was prepared by a spin-cast method (ca.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of polyisocyanides bearing oligothiophene pendants: higher-order structural control through pendant framework design

Ikai

Takagi

Shinohara

et al. 2015

Polym J

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L-Alanine-based polyisocyanides bearing oligothiophene (OT) pendants (poly-3a and poly-3b) were synthesized and the influence of the OT pendants on the chiroptical properties and helix-forming abilities of the polymers was investigated. Poly-3a bearing a quinquethiophene unit with two n-hexyl chains successfully formed a preferred-handed helical conformation by simultaneous interactions of the OT-pendant π-π stacking and hydrogen bonding of the amide groups. In contrast, poly-3b, which possesses a branched alkyl chain on behalf of the terminal n-hexyl chain of poly-3a, did not form a higher-ordered helical conformation. The results suggest that the structure of the alkyl chains positioned far from the polymer backbones remotely and sensitively affected the ability of the polymer to form a helical conformation. We also found that the structure of the OT pendants significantly affect the molecular weight as observed by AFM measurements. The polyisocyanide poly-3c bearing a bithiophene unit was additionally synthesized to examine the influence of the number of thiophene rings within the OT pendants on the higher-order structure formation.

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Section: Methodsmentioning

confidence: 99%

Synthesis of polyisocyanides bearing oligothiophene pendants: higher-order structural control through pendant framework design

Ikai

Takagi

Shinohara

et al. 2015

Polym J

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“…Some commercial systems also provide software that allows overlay of optical and AFM images. The resulting images exploit the complementary power of fluorescence and AFM imaging, which has been elegantly demonstrated previously [6–10]. In the aligned and overlaid hybrid images, the AFM image provides the overall conformational properties of the particles in the sample and the positions of the fluorescence signals identify the fluorescently labeled molecules.…”

Section: Introductionmentioning

confidence: 92%

“…In the last five years, there has been increasing interest in the combination of optical approaches and AFM [3–10], and integrated set-ups are available from different AFM manufacturers. Some commercial systems also provide software that allows overlay of optical and AFM images.…”

Section: Introductionmentioning

confidence: 99%

High accuracy FIONA–AFM hybrid imaging

Fronczek¹,

Quammen²,

Wang³

et al. 2011

Ultramicroscopy

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Multi-protein complexes are ubiquitous and play essential roles in many biological mechanisms. Single molecule imaging techniques such as electron microscopy (EM) and atomic force microscopy (AFM) are powerful methods for characterizing the structural properties of multi-protein and multi-protein–DNA complexes. However, a significant limitation to these techniques is the ability to distinguish different proteins from one another. Here, we combine high resolution fluorescence microscopy and AFM (FIONA–AFM) to allow the identification of different proteins in such complexes. Using quantum dots as fiducial markers in addition to fluorescently labeled proteins, we are able to align fluorescence and AFM information to ≥8 nm accuracy. This accuracy is sufficient to identify individual fluorescently labeled proteins in most multi-protein complexes. We investigate the limitations of localization precision and accuracy in fluorescence and AFM images separately and their effects on the overall registration accuracy of FIONA–AFM hybrid images. This combination of the two orthogonal techniques (FIONA and AFM) opens a wide spectrum of possible applications to the study of protein interactions, because AFM can yield high resolution (5–10 nm) information about the conformational properties of multi-protein complexes and the fluorescence can indicate spatial relationships of the proteins in the complexes.

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“…In addition, we succeeded in using a total internal reflection fluorescence microscope (TIRFM) to image single-molecule dynamic fluorescence 6,7 and a combination of an AFM and an objective-type TIRFM to simultaneous image the molecular structure and a novel fluorescent phenomenon. 8 In this study, we observed micro-Brownian motion of a single molecule of a chiral helical -conjugated polymer (Figure 1), 4,5,9 which has a structure of a molecular machine, namely a molecular spring, using a high-speed (rapid-scan) AFM at a solid/liquid interface. A high-speed AFM offers outstanding performance for observing the movement of single molecules in aqueous solution at room temperature.…”

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confidence: 99%

Single-Molecule Imaging of a Micro-Brownian Motion of a Chiral Helical π-Conjugated Polymer as a Molecular Spring Driven by Thermal Fluctuations

Shinohara¹,

Kodera²,

Ando³

2009

Chemistry Letters

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We observed a micro-Brownian motion of single molecules of a chiral helical -conjugated polymer as a molecular spring on mica substrate under n-octylbenzene at room temperature using high-speed (rapid scan) AFM. The average velocity at the chain end of the polymer was 67 nm s À1 at the observation point. The analytical result shows that the mean square displacement in a single polymer chain is proportional to the time and, hence, complies with Einstein's law of Brownian motion. The diffusion constant (D) is measured to be 8:2 Â 10 À15 m 2 s À1 at the solid/ liquid interface.Polymers are ubiquitous materials that display many excellent properties, and they have become indispensable in maintaining and developing our current way of life. In particular, -conjugated polymers are recognised as being part of the next generation of functional polymers for photonic and electronic applications.1-3 Nevertheless, it is difficult to discuss the correlation between their structures and properties at a molecular level, since these are diverse, dynamic, and, in general, very complex. If the structure and properties of a polymer could be directly observed, with minimal inferences or hypotheses, the relationship between polymer structures and functions could be clarified. Consequently, molecular devices of a polymer might be created based on new design concepts and new working principles, may be the soft nanomachines. Recently, we have achieved the direct observation of single molecules in a -conjugated polymer at room temperature using a scanning tunneling microscope (STM) 4 and an atomic force microscope (AFM) 5 to measure the chiral helical structure. In addition, we succeeded in using a total internal reflection fluorescence microscope (TIRFM) to image single-molecule dynamic fluorescence 6,7 and a combination of an AFM and an objective-type TIRFM to simultaneous image the molecular structure and a novel fluorescent phenomenon. 8 In this study, we observed micro-Brownian motion of a single molecule of a chiral helical -conjugated polymer (Figure 1), 4,5,9 which has a structure of a molecular machine, namely a molecular spring, using a high-speed (rapid-scan) AFM at a solid/liquid interface. A high-speed AFM offers outstanding performance for observing the movement of single molecules in aqueous solution at room temperature.10-12 However, we modified the specifications of this high-speed AFM in order to use even in the organic solvent, allowing successful imaging of the movement of a single molecule of a chiral helicalconjugated polymer at room temperature. In addition, we measured the flexibility of a single polymer chain as a fundamental property of a molecular spring.We cast tetrahydrofuran (THF, 50 mL Â 3) on freshly cleaved mica for removing water and cast n-octylbenzene (5 mL) immediately. This allowed us to cast a dilute tetrahydrofuran (THF) solution (10 À6 mol L À1 , 5 mL) of a chiral helical -conjugated substituted phenylacetylene polymer [(À)-poly(MtOCAPA)] (Figure 1) on a mica substrate for single-molecule imagin...

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Simultaneous imaging of the structure and fluorescence of a supramolecular nanostructure formed by the coupling of π‐conjugated polymer chains in the intermolecular interaction

Cited by 24 publications

References 15 publications

Synthesis of polyisocyanides bearing oligothiophene pendants: higher-order structural control through pendant framework design

Synthesis of polyisocyanides bearing oligothiophene pendants: higher-order structural control through pendant framework design

High accuracy FIONA–AFM hybrid imaging

Single-Molecule Imaging of a Micro-Brownian Motion of a Chiral Helical π-Conjugated Polymer as a Molecular Spring Driven by Thermal Fluctuations

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