Varying nanoparticle pseudostationary phase plug length during capillary electrophoresis

Abstract

Capillary electrophoresis based separations of the hypothesized Parkinson’s disease biomarkers dopamine, epinephrine, pyrocatechol, L-3,4-dihydroxyphenylalanine (L-DOPA), glutathione, and uric acid are performed in the presence of a 1 nM 11-mercaptoundecanoic acid functionalized gold (Au@MUA) nanoparticle pseudostationary phase plug. Au@MUA nanoparticles are monitored in the capillary and remain stable in the presence of electrically-driven flow. Migration times, peak areas, and relative velocity changes (vs. no pseudostationary) are monitored upon varying (1) the Au@MUA nanoparticle pseudostationary phase plug length at a fixed separation voltage and (2) the separation voltage for a fixed Au@MUA nanoparticle pseudostationary phase plug length. For instance, the migration times of positively charged dopamine and epinephrine increase slightly as the nanoparticle pseudostationary phase plug length increases with concomitant decreases in peak areas and relative velocities as a result of attractive forces between the positively charged analytes and the negatively charged nanoparticles. Migration times for neutral pyrocatechol and slightly negative L-DOPA did not exhibit significant changes with increasing nanoparticle pseudostationary plug length; however, reduction in peak areas for these two molecules were evident and attributed to non-specific interactions (i.e. hydrogen bonding and van der Waals interactions) between the biomarkers and nanoparticles. Moreover, negatively charged uric acid and glutathione displayed progressively decreasing migration times and peak areas and as a result, increased relative velocities with increasing nanoparticle pseudostationary phase plug length. These trends are attributed to partitioning and exchanging with 11-mercaptoundecanoic acid on nanoparticle surfaces for uric acid and glutathione, respectively. Similar trends are observed when the separation voltage decreased thereby suggesting that nanoparticle-biomarker interaction time dictates these trends. Understanding these analyte migration time, peak area, and velocity trends will expand our insight for incorporating nanoparticles in separations.

Analysis and applications of nanoparticles in capillary electrophoresis

“…However, there is a poor understanding of the interactions on the surfaces of NPs and the behavior of the bioconjugates as well as free NPs inside the capillary. Subramaniam et al evaluated the interactions between NPs and biomarkers of Parkinson's disease (i.e., dopamine, epinephrine, pyrocatechol, L-DOPA, glutathione, and uric acid) with different charges [62]. They monitored the migration time, peak areas, and changes in relative velocity upon varying the plug length of the NPs and the separation voltage, using 11-mercaptoundecanoic acid functionalized AuNPs.…”

Construção De Mini Forno Para Funcionalização Térmica De Fases Estacionárias Monolíticas

“…A pré-funcionalização serve para garantir a ancoragem das nanopartículas na FEM no momento da funcionalização, já que o agente de pré-funcionalização usado apresenta grupos tiois em sua estrutura que podem ligar-se eletrostaticamente e ou sob diferentes formas, com as AuNps. 18 Na etapa final ocorre a funcionalização, ou seja, a solução das AuNps é percolada por uma hora a temperatura ambiente pela FEM pré-funcionalizada. 17…”

CE and nanomaterials – Part II: Nanomaterials in CE

“…The potential of high-throughput DNA analysis using the suggested method is increased mainly due to the automatic replacement of the sieving matrices given by the low viscosity. In 2011, a detailed study of varying plug lengths of nanoparticle pseudostationary phase during CE analysis was published by Subramaniam et al [43]. Gold nanoparticles functionalized with 11-mercaptoundecanoic acid were used as an additive in the pseudostationary phase plug, and dopamine, epinephrine, pyrocatechol, L-3,4-dihydroxyphenylalanine, glutathione, and uric acid were used as analytes due to their biological importance.…”