The quartz crystal microbalance （QCM） was used to monitor the one-day incubation of human breast cancer cells （MCF-7） on the gold electrode. In combination with an optical microscope simulation experiment, the cell-population pictures at various stages, the QCM responses to the cells＇ adhesion, spreading and proliferation on the electrode surface were discussed. The △f0 and △R1 responses were found mainly from mixed effects of viscodensity and surface stress, and in proportion to the cell coverage, rather than to the number of cells at the electrode. The significant fore-and-aft changes in cyclic voltammetry and electrochemical impedance spectroscopy of the ferri-ferrocyanide redox couple also proved that the cells were adhesion to the gold surface.
Xue En JIAZhi Wei ZHANGLiang TANYou Yu ZHANGQing Ji XIEZhi Min HEShou Zhuo YAO
The combination of reflectance UV-Vis spec- troelectrochemistry with electrochemical quartz crystal microbalance (EQCM) and separate reflectance FTIR char- acterization were used to investigate the structural intercon- version for poly(o-phenylenediamine) (PoPD) between its ladder structure with phenazine units and polyaniline-like linear chains. The poly(o-phenylenediamine) films potentio- statically (0.8 V vs. SCE) grew on Au electrodes from 0.20 mol·L?1 H2SO4 (PoPD1) or 0.40 mol·L?1 NaOH (PoPD2) aque- ous solution containing 0.20 mol·L?1 Na2SO4 + 0.10 mol·L?1 o-phenylenediamine. By considering the mass of deposited PoPD2 film obtained from the EQCM data and the charge consumed under the current peak at ca. 0.6 V vs. SCE for oxidation of -NH2 groups in as-prepared PoPD2 during po- tential cycling in 0.10 mol·L-1 aqueous H2SO4, the molar per- centage of the polyaniline-like chains was estimated to be 19% (relative to total phenylenediamine units), being in agreement with the result obtained from a formaldehyde- combination experiment through the aminocarbonyl reaction. After 40-cycle potential sweeps between 0.2 and 0.8 V vs. SCE the polyaniline-like chains in PoPD2 could be com- pletely converted via intramolecular cyclization into the lad- der structure with phenazine units. However, PoPD1 was found to be perfectly composed of the ladder structure with phenazine units, and after 40-cycle potential sweeps between ?0.4 and 0.1 V vs. SCE only 2.5% in molar percentage of PoPD’s ladder structure could be converted into polyani line-like chains, suggesting that the ladder structure with phenazine units is thermodynamically more stable due to its possessing higher conjugation.
TU XinmanXIE QingjiWANG MeilingZHANG YouyuYAO Shouzhuo
