Ambipolar transport behavior in isoindigo-based conjugated polymers is observed for the first time. Fluorination on the isoindigo unit effectively lowers the LUMO level of the polymer and significantly increases the electron mobility from 10(-2) to 0.43 cm(2) V(-1) s(-1) while maintaining high hole mobility up to 1.85 cm(2) V(-1) s(-1) for FET devices fabricated in ambient. Further investigation indicates that fluorination also affects the interchain interactions of polymer backbones, thus leading to different polymer packing in thin films.

No abstract

Proliferating cells often have increased glucose consumption and lactate excretion relative to the same cells in the quiescent state, a phenomenon known as the Warburg effect. Despite an increase in glycolysis, however, here we show that non-transformed mouse fibroblasts also increase oxidative phosphorylation (OXPHOS) by nearly two-fold and mitochondrial coupling efficiency by ~30% during proliferation. Both increases are supported by mitochondrial fusion. Impairing mitochondrial fusion by knocking down mitofusion-2 (Mfn2) was sufficient to attenuate proliferation, while overexpressing Mfn2 increased proliferation. Interestingly, impairing mitochondrial fusion decreased OXPHOS but did not deplete ATP levels. Instead, inhibition caused cells to transition from excreting aspartate to consuming it. Transforming fibroblasts with the Ras oncogene induced mitochondrial biogenesis, which further elevated OXPHOS. Notably, transformed fibroblasts continued to have elongated mitochondria and their proliferation remained sensitive to inhibition of Mfn2. Our results suggest that cell proliferation requires increased OXPHOS as supported by mitochondrial fusion.