Comparison of detection techniques for capillary electrophoresis analysis of gold nanoparticles

Abstract

As metallic nanoparticles are growing in importance as analytes in CE, increases an interest in appropriate detection methods for their quantification in various samples. For gold nanoparticles (AuNPs), the most common UV detection poses intricacy of inadequate sensitivity that hinders the applicability of CE. With the objective of resolving this challenge, UV detection was compared with C(4) D and ICP-MS as alternative modes of detection for AuNPs. A C(4) D detector, applied under pressure-driven conditions, exhibited better sensitivity than a UV detector. However, C(4) D turned to be unsatisfactory to differentiate the signal of AuNPs at common CE conditions despite varying the nature of BGE and detection conditions. Due to intrinsic sensitivity and low background levels typical to Au, ICP-MS greatly surpasses UV detection. After optimization trials, CE-ICP-MS gained the LOD of AuNPs as low as 2 × 10(-15) M, as well as an excellent performance in terms of signal stability and linearity. Also importantly, the optimized BGE appears to be well matched to explore the behavior of AuNPs in biologically relevant systems. This was demonstrated by probing the interaction between AuNPs and the main blood-transporting protein, HSA.

Improved separation and size characterization of gold nanoparticles through a novel capillary zone electrophoresis method using poly(sodium4‐styrenesulfonate) as stabiliser and a stepwise field strength gradient

“…2.6 pmol, for an injection volume of 85 nL). Significantly lower values have been obviously achieved when using detection modes like ICP‐MS which are surely more sensitive while involving expensive and complex instrumentation. Really, the separation approach developed in the present work was not aimed to overcome the limited sensitivity of UV‐Vis detection but rather to improve resolution by emphasizing the retardation and relaxation effects on AuNP electrophoretic moving.…”

Recent advances in CE‐MS coupling: Instrumentation, methodology, and applications

“…For gold NPs, CE‐ICP‐MS gained the LOD as low as 2 × 10 −15 M, as well as an excellent performance in terms of signal stability and linearity. This was demonstrated by probing the interaction between gold NPs and the main blood‐transporting protein, human serum albumin . The studies on the interaction of gold‐containing drug, auranofin, and plasma proteins proved that cysteine‐34 was the main reaction site for auranofin in human serum albumin, the major auranofin‐interacting protein in plasma .…”

Characterization of interactions of metal‐containing nanoparticles with biomolecules by CE: An update (2012–2016)

“…By the rules of their intended use the metallic nanoparticles are designed to be fairly stable against aggregation or agglomeration under blood electrolyte conditions. Therefore, neutral BGEs based on Good's buffers are of preferable choice to study biointeractions of gold nanoparticles (AuNPs) (HEPES ) or nanorods (AuNRs) (PIPES ), silver nanoparticles (AgNPs) (CHES ), quantum dots (QDs) (HEPES ), or iron‐oxide nanoparticles (MOPS ). Peak dispersion challenge due to the tendency of nanoparticles, having large specific areas, to adsorb onto the capillary wall is greatly bypassed by using such BGEs that impart negative surface charge and sufficient electrostatic repulsion.…”

“…Peak dispersion challenge due to the tendency of nanoparticles, having large specific areas, to adsorb onto the capillary wall is greatly bypassed by using such BGEs that impart negative surface charge and sufficient electrostatic repulsion. On the other hand, high‐salt electrolytes though physiologically welcome are to be avoided because of detection system incompatibility . Obviously, when analyzing nanoparticles exposed to human serum via ex vivo incubation, the number of bioconjugates to resolve increases (see Section ) and more effort is required to gain the baseline separation .…”