Supramolecular Self‐Assembly of DNA with a Cationic Polythiophene: From Polyplexes to Fibers

Abstract

Cationic polythiophenes constitute an interesting class of polymers for prospective applications in imaging, gene delivery and biosensing, as they combine solubility in aqueous media and have sensitive optical properties for the detection of biomolecules such as DNA. Here, we study the supramolecular self‐assembly of poly[3‐(6’‐(trimethylphosphonium)hexyl)thiophene‐2,5‐diyl] ( P3HT‐PMe 3 ) with different types of DNA such as single‐stranded oligonucleotides or long genomic DNA. Self‐assembly in buffered aqueous solution yields polyplexes (polymer/DNA complexes) with hydrodynamic radii ranging from 7 nm to around 25 nm, as observed by Taylor Dispersion Analysis. In these polyplexes, the achiral polymer presents chiroptical signals induced by supramolecular organization along chiral DNA. When the solution of long DNA/ P3HT‐PMe 3 is deposited on surfaces, tens of μm‐long fibers are formed by condensation of DNA and compaction of the polyplexes, as evidenced by microscopy techniques.