Plumbagin: A New Route to the Electroanalytical Determination of Cystine

Abstract

The interaction between 5-hydroxy-1,4-naphthoquinone and cysteine was found to give a clearly resolved voltammetric signature that could be used as an electrochemical assay for the thiol. A structure-function study assessed the nature of the resulting voltammetric profile and the highly selective response to cysteine. The translation of the system as the basis of an assay for the determination of cystine was investigated using mercaptopropanol as the in situ reducing agent. The lack of response to the latter and high recovery performance of the label opens up a new direction for the one pot, mercury free determination of cystine.

Covalent Modification of Nanoparticle‐Imprinted Matrices for Selective Nanoparticle Recognition

“…The electropolymerized polyplumbagin layer has an unsubstituted carbon atom at the quinone ring system available for a conjugate addition (Figure 1e) that can be used for such modifications of the matrix. [49,52,53] Accordingly, the electropolymerized polyplumbagin layer was subjected to conjugate addition of 1,2-ethanedithiol or cysteamine to introduce thiol or amine functional groups at the unsubstituted carbon atom in ChemElectroChem the quinone ring (Figure 1e). [54][55][56] The sample codes aredithiol/ polyplg/plg(SiO 2 À NH 2 )/GC and cysteamine/dithiol/plg-(SiO 2 À NH 2 )/GC, respectively.…”

“…Post functionalization of the matrix can introduce functional groups into the matrix, that can be used to exploit specific interactions with analyte NPs and their ligands. The electropolymerized polyplumbagin layer has an unsubstituted carbon atom at the quinone ring system available for a conjugate addition (Figure 1e) that can be used for such modifications of the matrix [49,52,53] . Accordingly, the electropolymerized polyplumbagin layer was subjected to conjugate addition of 1,2‐ethanedithiol or cysteamine to introduce thiol or amine functional groups at the unsubstituted carbon atom in the quinone ring (Figure 1e).…”

Smart platform for the time since death determination from vitreous humor cystine

“…The analytical determination of this amino acid is not only important for TSD but any change in its concentration can cause diseases like HIV, cancer, sepsis, ulcerative colitis and many others (Droge and Holm, 1997) however it is also important to clinical diagnosis purpose. Methods such as spectrofluorimetry (Ensafi et al, 2009), colorimetry (Morioka and Kobayashi, 1997;Grote, 1931;Shinohara, 1935), iodimetry (Virtue and Lewis, 1934), liquid chromatography (Wang et al, 2007), electrochemistry (Mikus et al, 2003;Li et al, 2010;Damle et al, 2010) and spectrophotometry (Chrastil, 1989;Chrastil, 1990) are developed for the detection of cystine. Colorimetric methods are considered to be more appropriate, attractive and simple as compared to the sophisticated instruments applied till date.…”

A novel and environmentally friendly colorimetric method for detection of cystine in human urine using unmodified gold nanoparticles

“…1 Cystinuria could be characterized by high concentrations of cystine in human urine (usually >400 mg L À1 ). 2 Several methods for the analysis of cystine have been developed during the past decades, including iodimetry, 3 liquid chromatography, 4 electrochemistry, [5][6][7] spectrophotometry, 8,9 spectrouorimetry 10 and colorimetry. [11][12][13] Among these methods, colorimetric assay is most attractive, especially in a resource poor setting, due to its simplicity and no requirement for sophisticated instruments.…”