Work

Ultra-high sensitivity detection and characterization of heterogeneous magnetic nanoparticles by dual cycles of dual-stage electrokinetic preconcentration

Year: 2025

Type: article

Abstract: BACKGROUND: For healthcare applications of nanoparticles (NPs), their analysis and characterization are essential to obtain information on their heterogeneity regarding their size, shape, and surface chemistry or functionalization. Among the different analytical methods available, capillary electrophoresis (CE) is a well-established technique for such purpose. Nevertheless, CE approaches often suffer from unsatisfactory detection sensitivity when dealing with low NPs concentrations. In a related context, working with low NPs concentrations is essential in cellular engineering to minimize their cytotoxicity, which is notably caused by nanoparticle aggregation at high concentrations due to insufficient colloidal stability. RESULTS: We present in this study a novel principle of dual cycles of dual-stage electrokinetic preconcentration to drastically improve the detection sensitivity for characterization of core-shell magnetic nanoparticles (MNPs) by CE coupled with laser-induced fluorescent (LIF) detection. This approach is based on the combination and repetition of large volume sample stacking with electroosmotic pump (LVSEP) and transient isotachophoresis (tITP) using modulation of the electro-osmotic flow without recourse to any capillary coating. This dual cycle LVSEP-tITP approach allows enrichment of the MNPs having heterogeneous mobilities from a sample volume equivalent to 170 % of the total capillary volume. To demonstrate the significance of dual cycle LVSEP-tITP, the preconcentration principle was applied for CE-LIF of different populations of labelled core-shell MNPs functionalized with sulfobetaine having different sizes (40 and 125 nm) and forms (spherical and non-spherical), offering enrichment factors up to 110-fold compared to that obtained with CE-LIF without the preconcentration steps. SIGNIFICANCE: This study describes a new preconcentration concept for high-performance detection and electrokinetic fingerprinting of MNPs with heterogeneous subpopulations and mobilities. This will open the floor for characterization of MNPs in their suspension media after their multiple-step synthesis, providing guides for re-optimization of the synthesis process.

Source: Analytica Chimica Acta

DOI: 10.1016/j.aca.2025.345029