Scanning electrochemical microscopy under illumination: an elegant tool to directly determine the mobility of charge carriers within dye-sensitized nanostructured semiconductors

The diffusion constant of the ferrocenium ion in dye-sensitized nanostructured materials has been determined by time-of-flight experiments under working solar cell conditions with scanning electrochemical microscopy.     

Electrochemically polymerised composites of multi-walled carbon nanotubes and poly(vinylferrocene) and their use as modified electrodes: application to glucose sensing

We report electrochemical composites of multi-walled carbon nanotubes (MWCNTs) with poly(vinylferrocene) (PVF). The polymeric architecture is prepared by first immobilising the MWCNTs onto a glassy carbon substrate, which acts to introduce electrical current into the composite, with the MWCNTs acting as 'molecular wires'. PVF films of varying surface coverages can be obtained by simply controlling the time a constant potential of +0.7 V (vs. Ag) wire is applied; with the characteristics of the derivatised MWCNTs examined by cyclic voltammetry and scanning electron microscopy.The application of the composite for glucose determination in aqueous solutions was investigated using linear sweep voltammetry, where it was found that the composites supported on glassy carbon substrates are superior to bare glassy carbon electrodes polymerised with PVF, likely due to the comparatively higher number of electrocatalytic centres in the former. This protocol was successfully transferred to prepare a PVF-MWCNT-paste electrode which was applied to glucose detection in diluted laked horse blood. The obtained results show potential and promising practical application for the polymer-derivatised MWCNT-modified electrodes in amperometric sensors for glucose determination.     

New gold(III) chlorophenyl terpyridine complex: Biomolecular interactions and anticancer activity against human oral squamous cell carcinoma

In this work we synthesized new monofunctional gold(III) complex [Au(Cl-Ph-tpy)Cl]Cl₂ (Cl-Ph-tpy = 4′-[4-chlorophenyl]-2,2′:6′, 2″-terpyridine). This complex was characterized by UV–Vis, NMR, IR, and ESI-MS spectrometry. The kinetic study of the substitution reactions of the Au-Cl-Ph-tpy complex with biomolecules showed that the rate constants depend on the nature of the entering nucleophile. Based on the calculated values of entropy (∆H^≠ > 0) and enthalpy (∆S^≠ < 0) the proposed substitution mechanism is associative. Additionally, the relative stability and thermodynamic properties of Au-Cl-Ph-tpy complex were compared with the analogue Au-tpy complex by the B3LYP/def2-svp method. DNA/BSA binding studies showed that Au-Cl-Ph-tpy complex interacts with CT DNA through the intercalation and moderately quenches the fluorescence of tryptophan residues in serum albumin (BSA). Molecular docking confirmed results obtained by spectroscopic experiments and suggested site I (subdomain IIA) for binding of Au complex to BSA. We demonstrated that the Au chlorophenyl terpyridine complex possessed significant in vitro cytotoxic activity against human oral squamous carcinoma cells (CAL-27), induced apoptosis, inhibited proliferation of CAL-27 cells, and induced cell cycle disturbance. Treatment of CAL-27 cells with the Au complex enhanced expression of cyclin-dependent kinase inhibitors p21 and p27, resulting in cell cycle arrest in the G1 phase, reduced the percentage of CAL-27 cells in S phase and decreased expression of Ki-67. Additionally, Au complex reduced expression of phosphorylated STAT3 and downstream regulated molecules associated with cancer stemness, NANOG, and Sox2 protein.