Biophysical Society Thematic Meeting | Tutzing 2026

Single-Molecule FRET: The Next 30 Years

Poster Abstracts

46-POS Board 24 SINGLE-MOLECULE FRET REVEALS THE STRUCTURAL DYNAMICS OF CONJUGATED POLYMER AGGREGATES IN SOLUTION Maria Ott 1 ; 1 Martin-Luther-Universität Halle-Wittenberg, Institute of Biochemistry and Biochemistry, Halle (Saale), Germany Organic electronics depend on the controlled self-assembly of conjugated polymers, whose optoelectronic performance is governed by solution-state aggregation. However, conventional structural characterization is challenged by strong visible absorption and polydispersity. Here, we demonstrate that a combined approach of spectral-filtered fluorescence correlation spectroscopy (FCS) and single-molecule Förster resonance energy transfer (smFRET) provides a powerful means to probe the time-dependent aggregation of a high-performance NDI-T2-based copolymer with varying side-chain architectures. This approach enables real-time, single aggregate characterization through inter- and intramolecular energy transfer, fluorescence lifetime, and anisotropy[1]. We identify distinct solvent- and side-chain-dependent aggregation pathways, which we attribute to a structural evolution driven by side-chain modulated interactions and progressive backbone planarization.[2] These findings offer a mechanistic understanding of aggregation dynamics of conjugated polymers in solutions and open a new pathway for the rational design of polymer inks. As single molecule techniques advance toward higher throughput and multiplexing, this approach holds strong promise for real-time monitoring of self-assembly in printed electronics, enabling optimized formulations and improved film morphology. [1] Fahimi M, Matsidik R, Sommer M, Ott M, Selective Fluorescence Correlation Spectroscopy to reveal solvent effects on P(NDI2OD-T2) copolymers in solutions, Macromolecules 2026, 59, 7, 4580–4590[2] Schäfer E, Sommer M and Ott M, Time-Dependent Structure Assessment of Conjugated Polymer Aggregates in Solution by Single-Molecule Fluorescence Spectroscopy, Macromolecules 2026, 59, 1740-1751

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