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The Photophysics of Polythiophene Nanoparticles for Biological Applications |
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| Authors: | Dr Ilaria Bargigia Dr Elena Zucchetti Dr Ajay Ram Srimath Kandada Dr Miguel Moreira Dr Caterina Bossio Dr Walter P D Wong Prof Paulo Barbeitas Miranda Dr Paolo Decuzzi Prof Cesare Soci Prof Cosimo D'Andrea Prof Guglielmo Lanzani |
| Affiliation: | 1. Center for Nano Science and Technology @Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano, Italy;2. Center for Nano Science and Technology @Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano, Italy
Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy;3. Laboratory of Nanotechnology for Precision Medicine, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy;4. School of Material Science and Engineering, Nanyang Technological University, Singapore, 637371 Singapore;5. Center for Nano Science and Technology @Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano, Italy Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy São Carlos Physics Institute, University of São Paulo, CP 369, Sao Carlos, SP, 13560-970 Brazil |
| Abstract: | 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. |
| Keywords: | biological applications conjugated polymers nanoparticles photophysics ultrafast spectroscopy |