Nonionic surfactant‐capped gold nanoparticles for selective enrichment of aminothiols prior to CE with UV absorption detection

Abstract

In this study, we describe the use of Tween 20-capped gold nanoparticles (AuNPs) as selective probes for the extraction of aminothiols from an aqueous solution. Tween 20 molecules noncovalently attached to the surface of AuNPs to form Tween 20-AuNPs were used for the selective extraction of aminothiols through the formation of Au-S bonds. After extraction and centrifugation, the aminothiols were detached from the surface of the AuNPs by adding DTT in a high concentration. We used this probe in combination with CE and UV absorption detection. On-line concentration and separation of the released aminothiols were performed by using 1.6% v/v poly(diallyldimethylammonium chloride) as an additive in CE. Under optimal extraction and stacking conditions, the LOD at a S/N of 3 were 28, 554, and 456 nM for glutathione (GSH), cysteine (Cys), and homocysteine (HCys), respectively. In comparison with the normal injection without the extraction procedure, approximately 2280-, 998-, and 904-fold improvements in the sensitivity were observed for GSH, Cys, and HCys, respectively. We have validated the application of our method on the basis of the analysis of GSH and HCys in human urine samples. It is believed that this approach has significant potential to be extended to clinical diagnosis.

Capillary electrophoresis coupled with chloroform‐acetonitrile extraction for rapid and highly selective determination of cysteine and homocysteine levels in human blood plasma and urine

“…Second, the technique made it possible to determine Hcy and Cys levels in urine. To date, only one CE‐UV method that can be used for urine analysis has been described; however, that method involved extraction using nanoparticles with time‐consuming sample preparation and the CE analysis had a sensitivity that was more than twofold lower than that obtained by using the current approach.…”

“…However, it was not suitable for the analysis of complex biological matrices. The use of gold nanoparticles for thiol extraction solves this problem; however, the sample preparation and analysis time are significantly increased .…”

A methodological approach based on gold-nanoparticles followed by matrix assisted laser desorption ionization time of flight mass spectrometry for the analysis of urine profiling of knee osteoarthritis

“…On the one hand, proteins containing residues of cysteine must be present as is trough sulphur that the proteins and peptides attach to the gold [50]. On the other hand, peptides and proteins have positive charges depending on the pH of the solution, whilst gold nanoparticles present a negative zeta (ζ potential).…”

Recent developments in CE and CEC of peptides (2009–2011)

“…After optimization of SPE operational parameters, such as sample pH, loading volume, elution volume and composition, a 40‐fold preconcentration and detection limit at 1 ng/mL (∼5 nM) level were achieved for 3200 nL loaded sample volume. Selective extraction of aminothiols including tripeptide glutathione (GSH) from water solution and human urine was achieved using a new type of sorbent, non‐ionic surfactant (Tween 20)‐capped gold nanoparticles (GNPs), via the formation of Au‐S bonds 57. The aminothiols were detached from the GNPs by high concentration of DTT.…”