A Chemically-Bound Glutathione Sensor Bioinspired by the Defense of Organisms against Heavy Metal Contamination: Optimization of the Immobilization Conditions

Abstract

Abstract:The influence of the experimental conditions (glutathione concentration and incubation time and temperature) concerning the covalent immobilization of glutathione via carbodiimide coupling on the behavior of a glutathione modified screen-printed carbon electrode obtained by electrografting is evaluated. The optimized parameters fasten the modification process and improve the performance of the sensor as compared to the usual procedure. This suggests the convenience of a tailored preparation of metal sensors based on metal-binding biomolecules such as glutathione.

Selenocystine modified screen-printed electrode as an alternative sensor for the voltammetric determination of metal ions

“…In the case of Cyst-SPCNFE however, slightly higher LODs were obtained and the LOD for Cd(II) does not allow its detection below the legal limits. The LODs achieved with SeCyst-SPCNFE are also similar to those reported for Cd(II) and Pb(II) with carbon electrodes modified following a similar strategy with thiols [7,19,22,23] or crown ethers [8] (between 1.5 and 3.3 µg L -1 for Pb(II) and 1.96 and 4.7 µg L -1 for Cd(II)), with antimony [27], bismuth [28] or mercury [9] films deposited on carbon screen printed electrodes (between 0.03 and 10 µg L -1 for Pb(II) and 0.2 and 8 µg L -1 for Cd(II)), with carbon nanomaterial based electrodes [29] (between 1 and 20.7 µg L -1 for Pb(II) and 0.001 and 2.8 µg L -1 for Cd(II)) or with metal nanoparticles based electrodes [29] (between 0.2 and 4.9 µg L -1 for Pb(II) and 0.9 and 4.9 µg L -1 for Cd(II)). Therefore, the better analytical performance, especially in terms of sensitivity, repeatability and reproducibility, achieved by SeCyst-SPCNFE, suggest that the immobilization of selenium based ligands onto carbon electrodes could be much better alternative for the determination of trace heavy metals ions.…”

“…The modification of carbon electrodes with Cyst and SeCyst was based on the aryl diazonium salt electrografting. This modification strategy has been previously reported for the immobilization of several thiols on carbon substrates [5,7,19,22,23] and it usually includes a final step where the thiol is dissolved in MES buffer so it can react with the carboxylic groups previously generated on the electrode surface. However, the poor solubility of Cyst and SeCyst in MES buffer does not allow this last reaction to take place.…”

Multifuntional Gold Nanoparticles for the SERS Detection of Pathogens Combined with a LAMP–in–Microdroplets Approach

“…Such biochemical mechanism of defense is based on the synthesis of small molecules, such as GSH with high affinity for heavy metal ions that can chemically bind them to decrease their toxicity favoring their elimination. GSH is included in these biosynthesized small molecules and therefore it was selected to functionalize a SERS substrate based on AuNPs [37,38]. In the methodology presented here, we took advantage of two components of the LAMP reaction: magnesium (Mg 2+ ) and pyrophosphate (P 2 O 7 4− ) ions.…”

“…Briefly, three thiolated molecules, GSH, 1NAT and TPEG, with different functionalities were covalently bonded to monodisperse 14 nm AuNPs via a Au-S bond, which acts as SERS optical enhancer [50]. These thiolated molecules were strategically selected as GSH is a chelating agent of divalent metal ions [37], and TPEG molecules act as a stabilizing agent against magnesium ion-induced aggregation, as previously reported [26]. Thus, the detection of the DNA amplification was based on the aggregation of 1NAT:GSH:TPEG-AuNPs triggered by the complexation of AuNPs via the carboxylic group of GSH and pyrophosphate released by the incorporation of dNTPs into the DNA strand during polymerization with free magnesium ions (see scheme on Figure 2a).…”

“…The design of these multifunctional AuNPs was bioinspired by the mechanisms of defense of organisms against divalent heavy metal contamination. One of these biochemical mechanisms is the synthesis of GSH due to its high affinity for divalent heavy metal ions, which allows the decrease of their toxicity, easing their elimination [37,38]. Thus, the goal of this study was to determine the possibility of combining these bioinspired AuNPs with LAMP-based DNA amplification performed in microdroplets, for the detection of L. monocytogenes using SERS as analytical readout.…”