Joshua Oni

Pyrrole functionalised metalloporphyrins as electrocatalysts for the oxidation of nitric oxide

Pyrrole-functionalised tetracarboxyphenyl porphyrin and trimethoxyphenylcarboxy-phenyl porphyrin containing Ni, Mn and Pd as the central metal ion were used to modify Pt-disk microelectrodes (slashed circle 50 mum) (by repetitive cyclic voltammetry, dip-dry and pulse-amperometry methods) for the detection of nitric oxide (NO). Electrodes modified with Mn(II) trimethoxyphenylcarboxyphenyl porphyrin using the pulse amperomery approach, were found to be sensitive, stable and fast in response towards the oxidation of NO. Thus, they were used for the detection of NO release from a population of transformed human umbilical vein endothelial cells (T-HUVEC) into a droplet of electrolyte solution following stimulation with vascular endothelial growth factor (VEGF). The electrode surface was covered with an additional layer of Nafion(R) to prevent interference from anionic molecules such as nitrite.

Detection of NO release from endothelial cells using Pt micro electrodes modified with a pyrrole-functionalised Mn(II) porphyrin

Pt-disk electrodes (50 μm diameter) were modified with pyrrole-functionalised Mn(II) trimethoxycarboxyphenylporphyrin by means of an electrochemical pulse technique leading to stable and sensitive microsensors that displayed electrocatalytic activitiy suitable for the detection and quantification of nitric oxide (NO). In order to improve selectivity, a thin layer of Nafion® was deposited on top of the porphyrin-modified surface of the microsensor by means of a dip-coating procedure. These microelectrodes were successfully applied for the detection of the secretion of NO from a population of human umbilical vein endothelial cells (HUVEC) into a small volume of electrolyte.