Gold nanoparticles – from synthesis to extraction of biological thiols and CE-LIF analysis
|Fakulta / Pracoviště MU
|Gold nanoparticles (AuNPs) exhibit several unique properties including redox activity, surface plasmon resonance, a high surface-to-volume ratio, or spontaneous formation of a stable Au-S dative bond with biological thiols. Biothiols are endogenous compounds that play a significant role in biological systems and their altered levels have been associated with disease states. However, levels of biothiols are low in non-invasive biological samples such as saliva or exhaled breath condensate (EBC). In this work, AUNP synthesis and AuNP-based extraction of biological thiols from samples followed by CE-LIF analysis are investigated. AuNPs were synthetized by reduction of tetrachloroauric acid by trisodium citrate. The increasing gold-to-citrate ratio led to synthesis of bigger particles (~30-60 nm) but of worse particle size monodispersity. The particle size and distribution were determined by scanning electron microscopy and UV–Vis spectrophotometry. AuNPs with the size of ~17 nm were further used for investigation of the AuNP-biothiol interaction using different AuNP stabilizing agents (i.e., citrate, Tween 20) by UV–Vis spectrophotometry. Binding of cysteamine and homocysteine on the AuNP surface caused rapid AuNP aggregation and a color change of the suspension from red to blue. On the other hand, glutathione did not cause any visible aggregation. For biothiol extraction and enrichment, EBC samples were incubated with AuNPs and different reagents were tested (i.e., dithiothreitol, thioglycolic acid) to release biothiols from AuNPs. Prior to CE-LIF analysis, biothiols were derivatized with eosin-5-maleimide and separated in the 15 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid electrolyte (pH 7.5). A further optimization of biothiol release from AuNPs to achieve better enrichment will be conducted in future research.