Studies of GSH interactions with toxic heavy metals (Hg, Cd, Pb) are important to gain better understanding of the environmental effects on human health. In particular, the elucidation of mechanisms leading to increased susceptibility to autism [19, 20], diabetes , and other diseases [21-26] due to diminished active GSH levels in cells and body fluids and the reduced antioxidation capacity  to protecting against radicals, should enable us to devise preventive measures to effectively diminish the spread and decrease the occurrence of these diseases. The involvement of GSH in counteracting heavy metal poisoning and organic peroxide neutralization is associated with its rich functionality and its key role in the GSH/GSSG system of redox regulation in living organisms.In this work, we have investigated the immobilization of GSH on a cysteamine-SAM (CA-SAM) formed on Au piezoelectrodes by adsorptive dissociation of a disulphide, cystamine. The change in film permeability was investigated using Hg(II) ion probe which offers rich reactivity for voltammetric analysis and large molar mass easily detectable by the electrochemical quartz crystal nanogravimetry (EQCN) [28, 29]. The electrochemistry of Hg(II) on noble metal electrodes has been studied extensively on polycrystalline Au [30-37], Au nanoparticles on glassy carbon  and on single crystal Au(111) surface [39-49]. Hg deposition on graphite [50, 51] and platinum  electrodes have been investigated using EQCN. Thin Hg films on glassy carbon [53-56] and Ag microdisk  have been developed for heavy metal speciation by stripping voltammetric methods. In our recent studies of GSH-SAM on Au [3, 4], we have observed easy penetration of Hg(II) ions and their discharge at the bottom of ion-channels. In the present work, the films were modified by immobilization of GSH on CA-SAM to control the film permeability and to selleck screening library uncover the thiol group of GSH to enhance functionality of the film.2.?Results and Discussion2.1. EQCN voltammetric analysis of Hg(II) processes at Au/CA and Au/CA-GSH piezoelectrodesThe electrochemical processes on a cysteamine-SAM (CA-SAM) modified Au electrode are hindered by blocking the access of electroactive species to the electrode surface. However, due to the short length of the carbon chain, the CA-SAM films are less compact and more disordered than aminothiol films with longer alkyl chains. On the other hand, the glutathione-SAM films (GSH-SAM) with longer peptide branches form gated ion channels with high ion permeability [1-5, 65-67]. In the following experiments, we have examined the effect of GSH bound to the CA-SAM on Hg(II) permeability and reactivity and found rather unusual behavior of these films.