The photophysics of polythiophene nanoparticles for biological applications

• Main Authors: Bargigia, Ilaria, Zucchetti, Elena, Kandada, Ajay Ram Srimath, Moreira, Miguel, Bossio, Caterina, Wong, Walter P. D., Miranda, Paulo Barbeitas, Decuzzi, Paolo, Soci, Cesare, D'Andrea, Cosimo, Lanzani, Guglielmo
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Nanotechnology; Biological Applications; Conjugated Polymers
• Online Access: https://hdl.handle.net/10356/150565
• Institution: Nanyang Technological University

In this work the photophysics of poly(3-hexylthiophene) nanoparticles (NPs) is investigated in the context of their biological applications. The NPs, made as colloidal suspensions in aqueous buffers, present a distinct absorption band in the low-energy region. On the basis of systematic analysis of absorption and transient absorption (TA) spectra taken under different pH conditions, this band is associated with charge-transfer states generated by the polarization of loosely bound polymer chains and originating from complexes formed with electron-withdrawing species. Importantly, the ground-state depletion of these states upon photoexcitation is active even on microsecond timescales, thus suggesting that they act as precursor states for long-living polarons; this could be beneficial for cellular stimulation. Preliminary transient absorption microscopy results for NPs internalized within the cells reveal the presence of long-living species, further substantiating their relevance in biointerfaces.