Amperometric Quantification of S-Nitrosoglutathione Using Gold Nanoparticles: A Step toward Determination of S-Nitrosothiols in Plasma.

S-Nitrosothiols (RSNOs) are carriers of nitric oxide (NO) and have important biological activities. We propose here the use of gold nanoparticles (AuNPs) and NO-selective amperometric microsensor for the detection and quantification of S-nitrosoglutathione (GSNO) as a step toward the determination of plasma RSNOs. AuNPs were used to decompose RSNOs with the quantitative release of free NO which was selectively detected with a NO microsensor. The optimal [GSNO]/[AuNPs] ratio was determined, corresponding to an excess of AuNP surface relative to the molar GSNO amount. Moreover, the influence of free plasma thiols on this method was investigated and a protocol based on the blocking of free thiols with iodoacetic acid, forming the carboxymethyl derivative of the cysteine residues, is proposed.

Carbon nanotubes, phthalocyanines and porphyrins: attractive hybrid materials for electrocatalysis and electroanalysis.

The manuscript discusses different ways of forming hybrid materials between single (SWCNT) or multi (MWCNT) walled carbon nanotubes and biomimetic compounds such as metalloporphyrins, metallophthalocyanines and other MN4 complexes. The hybrid materials are employed for electrocatalysis of reactions such as oxygen and hydrogen peroxide reduction, nitric oxide oxidation, oxidation of thiols and other pollutants. Methods of characterizing the hybrid materials such as cyclic voltammetry (CV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM) are discussed.