Semiconducting Polymer Nanoporous Thin Films as a Tool to Regulate Intracellular ROS Balance in Endothelial Cells

The design of soft and nanometer-scale photoelectrodesable tostimulate and promote the intracellular concentration of reactiveoxygen species (ROS) is searched for redox medicine applications.In this work, we show semiconducting polymer porous thin films withan enhanced photoelectrochemical generation of ROS in human umbilicalvein endothelial cells (HUVECs). To achieve that aim, we synthesizedgraft copolymers, made of poly(3-hexylthiophene) (P3HT) and degradablepoly(lactic acid) (PLA) segments, P3HT-g-PLA. Ina second step, the hydrolysis of sacrificial PLA leads to nanometer-scaleporous P3HT thin films. The pore sizes in the nm regime (220-1200nm) were controlled by the copolymer composition and the structuralarrangement of the copolymers during the film formation, as determinedby atomic force microscopy (AFM) and transmission electron microscopy(TEM). The porous P3HT thin films showed enhanced photofaradaic behavior,generating a higher concentration of ROS in comparison to non-porousP3HT films, as determined by scanning electrochemical microscopy (SECM)measurements. The exogenous ROS production was able to modulate theintracellular ROS concentration in HUVECs at non-toxic levels, thusaffecting the physiological functions of cells. Results presentedin this work provide an important step forward in the developmentof new tools for precise, on-demand, and non-invasive modulation ofintracellular ROS species and may be potentially extended to manyother physiological or pathological cell models.