Composite Thiophene-Based Nanoparticles: Revisiting the PEDOT:PSS/P3HT Interface for Living-Cell Optical Modulation

Organic semiconducting nanoparticles (NPs) have been attracting increasing attention for their diverse applications in biotechnology, especially as photoactive materials for spatially controlled optical modulation of living-cell functions. Different approaches to optimize their efficacy and reliability have been recently attempted, including control of photophysical/-chemical properties, ad hoc tailoring of materials synthesis, and functionalization with biological moieties. Another promising strategy is offered by the realization of composite light-sensitive NPs, with a supramolecular architecture. This work reports on the fabrication and characterization of polymer NPs based on poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as prototypical examples of fully biocompatible, semiconducting and conducting materials, respectively. This peculiar NP architecture, with conducting islets distributed within the semiconducting phase, translates into optimization of charge dissociation and electron-transfer efficiency, as well as photocurrent generation increase by about an order of magnitude. As an example of relevant physiological interest, effective optical modulation of angiogenesis, driven by NPs, is demonstrated in primary human endothelial cells. The reported strategy is of general validity and broadens the tools available for spatiotemporally controlled, optical modulation of living-cell functions via engineering of the NP architecture and processes at the interface with living cells.