Small thiophene fluorophores in live cells promote protein self‐assembly into nanostructured fluorescent and electroactive microfibers

This review describes an unprecedented class of biocompatible protein-based microfibers obtained by exploiting the ability of small thiophene fluorophores: (1) to be spontaneously incorporated by living cells (2D or 3D) without causing any harm, (2) to act as protein self-assembly inducers, and (3) to transfer their long-lasting fluorescence and electroactivity properties to the protein-fluorophore microfibers. The process is driven by cell's own metabolism and leads to the generation of stable multifunctional microfibers exhibiting hierarchical order across several length-scales with morphologies varying from helical wires to rigid rods. Analogous microfibers are obtained following uptake of an appropriate thiophene fluorophore by small living organisms (Hydra vulgaris). Due to the high photostability of thiophene fluorophores, the entire process of fibers formation can be tracked in real time by LSCM. Moreover, the microfibers can be picked up and separated by their environment to assess their composition and properties by a variety of techniques including electrophoretic analyses and Q-TOF mass spectrometry, Tr-TUNA AFM and KPFM. This review also reports DFT calculations aimed to provide indications for the design of appropriate thiophene fluorophores for microfibers formation inside live cells.