Tunable Fluorescence of a Semiconducting Polythiophene Positioned on DNA Origami

Abstract

A novel approach for the integration of π-conjugated polymers (CPs) into DNA-based nanostructures is presented. Using the controlled Kumada catalyst-transfer polycondensation, well-defined thiophene-based polymers with controllable molecular weight, specific end groups, and water-soluble oligoethylene glycol-based side chains were synthesized. The end groups were used for the easy but highly efficient click chemistry-based attachment of end-functionalized oligodeoxynucleotides (ODNs) with predesigned sequences. As demonstrated by surface plasmon resonance spectroscopy, the prepared block copolymers (BCPs), P3(EO)T-b-ODN, comprising different ODN lengths and specific or repetitive sequences, undergo specific hybridization with complementary, thiol-functionalized ODNs immobilized on a gold surface. Furthermore, the site-specific attachment of the BCPs to DNA origami structures is studied. We demonstrate that a nanoscale object, that is, a single BCP with a single ODN handle, can be directed and bound to the DNA origami with reasonable yield, site-specificity, and high spatial density. On the basis of these results, we are able to demonstrate for the first time that optical properties of CP molecules densely immobilized on DNA origami can be locally fine-tuned by controlling the attractive π-π-stacking interactions between the CPs. In particular, we show that the fluorescence of the immobilized CP molecules can be significantly enhanced by surfactant-induced breakup of π-π-stacking interactions between the CP's backbones. Such molecular control over the emission intensity of the CPs can be valuable for the construction of sophisticated switchable nanophotonic devices and nanoscale biosensors.

Size Separation Techniques for the Characterisation of Cross-Linked Casein: A Review of Methods and Their Applications

“…For homogeneous hard sphere the ratio is equal to 0.775, for linear random coil is between 1 and 2, and for elongated conformations the ratio is up to 2 [200]. The determination of the diffusion coefficient and thus the hydrodynamic radius is also possible from the AF4 elution time (see Section 5.1, Equation (3)); however, both approaches possess advantages and limitations that were treated in depth in the bioconjugation of synthetic macromolecules and proteins [177,[201][202][203][204][205].…”

Synthesis and Characterization of a Regioregular Side‐Chain Semifluorinated Polythiophene

“…The side‐chain semifluorinated thiophene 5 was received with a yield of 42%. To selective gain the magnesio‐halogen exchange to generate 2‐bromo‐5‐chloromagnesio‐3‐(2‐((4,4,5,5,6,6,7,7,8,8,9,9,9‐tridecafluorononyl)oxy)ethyl)thiophene ( 2 ), compound 5 was selectively halogenated with one equivalent of N‐bromo‐succinimide (NBS) at the 2‐position followed by iodation at the 5‐position in accordance to the synthesis reported by Zessin et al The asymmetric nature of the final monomer precursor 3 enhances regioselectivity of resulting polymer. The regioselectivity of the magnesio‐iodine exchange reaction between 3 and i ‐PrMgCl was verified by quenching an aliquot of the reaction mixture with methanol.…”

Molecular Doping of a Water‐Soluble Polythiophene Derivative

“…Therefore, they are appealing for biomolecular‐based nanotechnological applications. By introducing water‐solubilizing, biocompatible side‐chains and specific end‐groups, a straight‐forward integration into biomolecular nanostructures is feasible, as we reported previously …”

“…Their synthesis route, namely Kumada catalyst‐transfer polycondensation (KCTP) or Grignard‐metathesis‐polymerization, follows a chain‐growth mechanism leading to polymers with fully regioregular head‐to‐tail thiophene orientation, an adjustable degree of polymerization and defined end‐group composition . Due to their well‐defined molecular structure, these polymers possess the outstanding ability to self‐assemble into complex structures with tailored optoelectronic properties . Therefore, they are appealing for biomolecular‐based nanotechnological applications.…”

“…[6] Due to their well-defined molecular structure, these polymers possess the outstanding ability to selfassemble into complex structures with tailored optoelectronic properties. [7][8][9] Therefore, they are appealing for biomolecularbased nanotechnological applications. By introducing watersolubilizing, biocompatible side-chains and specific end-groups, a straight-forward integration into biomolecular nanostructures is feasible, as we reported previously.…”