Polypyrrole/titanium dioxide composite nanodots coatings with light-controllable micro-domain potential for biomedical application

Surface potential is crucial in determining cell fate, but the influence of subcellular size micro-domain potential on cell fate remains explored. In this study, we present a novel bioactive surface composed of polypyrrole (PPy) on titanium dioxide (TiO 2 ) nanodots with a light-controllable micro-domain surface potential. SEM and TEM results show that TiO 2 nanodots are fully coated with a PPy layer. Photoluminescence and UV–Vis studies show that PPy-TiO 2 interactions generate a synergistic effect, reducing the band gap and enhancing electron-hole separation efficiency. Using Kelvin probe force microscopy, we observed that PPy/TiO 2 nanodots coatings exhibit a distinct micro-domain surface potential at the submicron level, dynamically modulated by external light stimulation. In vitro cell behavior evaluation showed that micro-domain surface potential coatings are biocompatible and cause no damage with limited illumination time. Our findings indicate that the light-controllable micro-domain composite nanodots coatings offer a promising approach to precisely control cellular behavior and provide a new perspective for designing stimuli-responsive charged biomaterials.