L-Cysteine gold complex

NO, Nitrogen oxide, iridium complex, 21 104 NO2SC3H7, L-Cysteine, gold complex, 21 31 NO3C3H7, Serine, copper complex, 21 115 NFPtSe2C24H28, Platinum(II), (A. /V-diethyldi-selenocarbamato)methyl(triphenylphos-phine)-, 21 10... 

Figure 4. Addition of cysteine to renai cytosol from a gold treated rat at a 100/L thiol/gold ratio shifts the gold from Peaks I, II, and to a lesser extent. III into the low molecular weight fraction. Peak IV, which is Au(cys)i (3). The smaii peak. IV, is a glutathione complex of gold. Conditions as in Figure 1.

The anticq>ated sur ce structure of the L-cysteine SAM on gold and its conq>lex witii Cu is shown in Figure 8. Electrochemical and XPS data suggest one Cu per two cysteine ligands (23). Literature reports indicate that the best complexation performance for tiie electrochemical sensors was at pH = S, the isoelectric point of L-cysteine. Similar optimal performance at pH = S was also observed for microcan ever deflection experiments. The deflection anq>litude caused by Cu complexation with the L-cysteine monolayer was much less for experiments performed at pH = 3 or pH = 7, than at pH = 5. 

Figure 8. Schematic representation of the molecular structure of the L cysteine self-assembled monolayer on the gold surface of the microcantilever and its complexation with Cu. ...

The use of self-assembled monolayers (SAMs) for the analysis of species has not been explored sufficiently. MPc complexes substituted with thiols may be used to form SAMs. SAMs of CoOBTPc or FeOBTPc on gold were used to detect L-cysteine in acid media -The electrodes were very stable and reproducible. Detection limits for cysteine as low as 3.1 x 10 M were obtained. SAMs of FeOBTPc, FeOHETPc, CoOHETPc were used as electrocatalysts for the detection of the thiols L-cysteine (Figure 7.3a), homocysteine and penicillamine (Figure 7.3b) with detection limits in the 10 -10 M range. Lower oxidation potentials for these thiols were observed for the FePc derivatives when compared to CoPc derivatives, Table 7.2. 

Nolan and coworkers reported the cytotoxicity of different neutral and cationic complexes. The first series of systems studied were Au-IPr derivatives bearing biocompatible moieties such as amino acids (L-proline or L-cysteine, Figure 7.16) [17]. In parallel, a second series of systems was selected, as it is well-known in the literature that cationic gold complexes can induce apoptosis of cancer cell lines. The IC50 were measured with LNCaP (prostate carcinoma) and MDA MB231 (breast carcinoma). 

Arrigan DWM, Le Bihan L (1999) A study of L-cysteine adsmption on gold via electrochemical desorption and copper(II) ion complexation. Analyst 124 1645-1649... 

Chernyak, A. S. and Shestopalova, L.F. (1976) Study of complexes of gold(I) with cysteine in an alkaline medium. Russian Journal of Inorganic Chemistry, English Translation, 21, 464—465. 

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