Fig. 1. Polymer devices for optical stimulation of ECFC cultures.

(A) P3HT polymer optical absorption spectrum. Insets show the chemical structure of the conjugated polymer and a sketch of the polymer device used for cell optical activation. ECFCs are cultured on top of P3HT thin films, deposited on glass substrates. (B) ECFC viability at fixed time points after plating (24, 48, and 72 hours). Cell cultures were kept in dark conditions at controlled temperature (37°C) and fixed CO₂ levels (5%). No statistically significant difference was observed between the glass and polymer substrates at any fixed time point (unpaired Student’s t test). (C) Experimental setup and optical excitation protocol for evaluation of polymer-mediated cell photoexcitation effects on cell fate. Polymer and control samples are positioned within a sterilized, home-designed petri holder. Light scattering effects are completely screened. The geometry and the photoexcitation protocol have been implemented to minimize overheating effects and to keep the overall extracellular bath temperature fairly unaltered. Thirty-millisecond-long green light pulses are followed by 70 ms in dark condition.