Piotr M. Diakowski

Deconvoluting Topography and Spatial Physiological Activity of Live Macrophage Cells by Scanning Electrochemical Microscopy in Constant-Distance Mode

Detection of reactive oxygen species (ROS) released from live macrophage cells (RAW264.7) without any addition of external redox mediators using constant-height and constant-distance mode scanning electrochemical microscopy (SECM) was presented in this Letter. The successful separation of the ROS profile from the topography of cells in the physiological condition was demonstrated by recording the amperometric current and probing position in the z-direction along with lateral coordinates at each pixel where an alternating current (AC) was kept constant. It was discovered that the nucleus region of the cell releases more ROS than other organelle regions and the height of the cell is approximately 4.8 μm. To our best knowledge, this work reports the first spatially monitored ROS release without the influence of cell morphology using SECM.

Interrogation of living cells using alternating current scanning electrochemical microscopy (AC-SECM).

In this paper we present the application of alternating current scanning electrochemical microscopy (AC-SECM) to the study of living cells. Commercial AFM instrumentation was modified to allow for performing robust AC-SECM measurements. Constant height AC imaging of the Cos-7 cells, performed directly in cell culture medium without the addition of a redox mediator, provided topographical information of the cell. Stationary tip measurements on the AC current were carried out to investigate the cellular activity of a single cell. The dependence of AC current magnitude on tip-to-sample separation distance was used to monitor real time changes in cell height of individual Cos-7 cells. Furthermore, AC-SECM was employed to observe changes in metabolic cellular activity stimulated by ethanol and phorbol-1,2-myristate-acetate-3. The effect of changing cellular activity on constant height AC-SECM imaging was also studied.

Effect of Ferrocene Position on Charge Transfer in ds-DNA Films

Ferrocene-labeled DNA systems where the Fc group is directly attached to deoxyuridine are investigated electrochemically in an effort to elucidate the electron transfer properties of these systems. The rigid linkage between the Fc group and the nucleobase provides control over the position of the Fc group within the ds-DNA and helps to elucidate the effect of the position of the redox label on the electrochemical behaviour of the ds-DNA films. Cyclic voltammetry, electrochemical surface plasmon resonance and scanning electrochemical microscopy measurements show that charge transfer (CT) in such systems is to a large extent controlled by the dynamic properties of surface-bound ds-DNA rather than by the CT through base-pair stacks.

Surface Analysis of Materials in Aqueous Solution by Localized Alternating Current Impedance Measurements

Differences in electrical conductivity provide a basis for identification of different components present at a material surface. Here it is demonstrated that this effect can be exploited for surface analysis of compound materials in solution by making localized alternating current impedance measurements.

Covalent modification of carbon nanotubes with ferrocene-lysine derivative for electrochemical sensors

Multiwalled carbon nanotubes (MWCNTs) were chemically modified with a ferrocene-lysine conjugate and the material was deposited on indium tin oxide (ITO) and the surfaces were evaluated for their ability to act as electrochemical sensors for chemical warfare agent (CWA) mimics methylphosphonic acid (MPA), ethylmethylphosphonate (EMP) and diethyl cyanophosphonate (DECP).