Electroosmotic flow modulation for improved electrokinetic preconcentration: Application to capillary electrophoresis of fluorescent magnetic nanoparticles

Abstract

It is reported in this study a new approach for modulation and even suppression of the electroosmotic flow (EOF) to achieve better electrokinetic preconcentration in capillary electrophoresis This is based on the augmentation of the buffer's concentrations to very high levels (more than a thousand of mM) without recourse to any dynamic/permanent coating nor viscous gel. The use of large weakly charged molecules as background electrolyte's constituents allows working at extreme concentration ranges without penalty of high electric currents and Joule heating. By this way, the electroosmotic mobility could be modulated over a wide range (2 -60 × 10 -5 cm 2 .V -1 .s -1 under alkaline conditions), and suppressed to levels equivalent to those obtained with several neutral coatings. For demonstration, this new approach was applied for sensitive determination of core-shell magnetic nanoparticles (CSMNPs) having high potential for healthcare applications such as imaging agents for diagnostics and controllable cargos for nanomedicine. Different profiles were achieved for purposemade and commercial magnetic nanoparticles using CE coupled with light-emitting-diode induced fluorescence (LEDIF) detection. Compared to the conventional capillary electrophoresis (CE-UV) method for characterization of magnetic nanoparticles, our proposed approach with fluorescent detection and EOF-assisted preconcentration offers almost 350-fold sensitivity improvement. Furthermore, our scheme can be used for monitoring the interaction between CSMNPs and target pharmaceutical molecules, serving for drug delivery development. A preliminary study with two antibiotics using this approach revealed that kanamycin interacts better with the target nanoparticles than amikacin.

Sensitivity enhancement in capillary electrophoresis and their applications for analyses of pharmaceutical and related biochemical substances

“…Nguyen et al. demonstrated the EOF‐assisted electrokinetic preconcentration using CE‐LIF to provide a better electrokinetic preconcentration of core‐shell magnetic nanoparticles (CSMNPs) having high potential for diagnostics and controllable cargos for nanomedicine [124]. The principle was based on the augmentation of the buffer's concentrations to very high levels without any dynamic or permanent coating or viscous gel.…”

“…This new approach was used for the sensitive determination of CSMNPs with high potential for healthcare applications such as imaging agents for diagnostics and controllable cargos for nanomedicine. Detection and interaction study of CSMNPs could be realized with 350-fold sensitivity improvement [124]. Online SPE-CE-MS was applied for the analysis of peptide biomarkers by Gascon et al [125].…”

Recent Applications of Dynamic On-Line Sample Preconcentration Techniques in Capillary Electrophoresis

“…To overcome this drawback, LVSS combines with the polarity switching (PS) technique to remove a vacant sample matrix from the capillary to the inlet vial. By employing the PS-LVSS technique, Chinese medicine component [43], magnetic [44], and 3-hydroxyaspartate [45,46] were successfully concentrated and separated in CE. Nguyen et al reported an effective PS-LVSS method for fluorescent magnetic nanoparticles [44].…”

“…By employing the PS-LVSS technique, Chinese medicine component [43], magnetic [44], and 3-hydroxyaspartate [45,46] were successfully concentrated and separated in CE. Nguyen et al reported an effective PS-LVSS method for fluorescent magnetic nanoparticles [44]. By the optimization of the BGE components for controlling electroosmotic flow (EOF), core-shell magnetic nanoparticles were well enriched with the SEF of 350.…”

Authenticity assessment of dairy products by capillary electrophoresis

“…Under these conditions, positive ions tend to thicken in the diffuse layer of the solution near the capillary wall: it is affected by the electric field while the bulk solution is globally neutral. Diffuse layer, globally positive, moves toward the cathode dragging with it the entire solution and giving rise to the EOF [77][78][79][80][81][82][83][84]. Due to the pulling force of the EOF, all molecules in the solution, positive, neutral, and even negative, will migrate toward the cathode.…”