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Adhesion is an essential parameter for stem cells. It regulates the overall cell density along the carrying surface, which further dictates the differentiation scheme of stem cells toward a more matured and specified population as well as tissue. Electronic control of the seeding density of neural stem cells (c17.2) is here reported. Thin electrode films of poly(3,4-ethylenedioxythiophene) (PEDOT):Tosylate were manufactured along the floor of cell growth dishes. As the oxidation state of the conjugated polymer electrodes was controlled, the seeding density could be varied by a factor of 2. Along the oxidized PEDOT:Tosylate-electrodes, a relatively lower density of, and less tightly bonded, human serum albumin (HSA) was observed as compared to reduced electrodes. We found that this favors adhesion of the specific stem cells studied. Surface analysis experiments, such as photoelectron spectroscopy, and water contact angle measurements, were carried out to investigate the mechanisms responsible for the electronic control of the seeding density of the c17.2 neural stem cells. Further, our findings may provide an opening for electronic control of stem cell differentiation.

Thin films of V(TCNE)x were deposited in ultrahigh vacuum using a film growth technique based on in situ chemical vapor deposition of tetracyanoethylene, TCNE, and bis-benzene vanadium, V(C6H6)2. The in situ preparation method enabled, for the first time, experimental analysis of oxygen-free films. X-ray magnetic circular dichroism measurements recorded at the V L(2,3) edge confirmed room temperature magnetic ordering. A combination of conventional photoelectron spectroscopy (PES) and resonant photoemission (RPE) measured at the V L3 edge shows that the highest occupied electronic state is V(3d) derived. The rearrangements of the TCNE- related valence electronic states observed in PES and the evidence of V(3d) and TCNE- pi(pi*) orbital overlap contained in RPE spectra, indicate that strong, covalent type bonding occurs between the vanadium and the TCNE molecules.