Sulfonic Functionalized Polydopamine Coatings with pH-Independent Surface Charge for Optimizing Capillary Electrophoretic Separations

• Published in: Molecules (Basel, Switzerland) Switzerland), 2024-04, Vol.29 (7), p.1600
• Main Authors: Long, Wenwen, You, Mingyue, Li, Jieli, Wang, Yan, Wang, Dan, Tao, Xueping, Rao, Li, Xia, Zhining, Fu, Qifeng
• Format: Article
• Language: English
• Subjects: Analysis; Blood vessels; capillary electrophoresis; capillary modification; Coatings; Dopamine; Efficiency; Hydrogen-ion concentration; Morphology; Nucleosides; pH-independent electroosmotic flow; Polymerization; Reproducibility; sulfonated polydopamine
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules29071600

Enhancing the pH-independence and controlling the magnitude of electroosmotic flow (EOF) are critical for highly efficient and reproducible capillary electrophoresis (CE) separations. Herein, we present a novel capillary modification method utilizing sulfonated periodate-induced polydopamine (SPD) coating to achieve pH-independent and highly reproducible cathodic EOF in CE. The SPD-coated capillaries were obtained through post-sulfonation treatment of periodate-induced PDA (PDA-SP) coatings adhered on the capillary inner surface. The successful immobilization of the SPD coating and the substantial grafting of sulfonic acid groups were confirmed by a series of characterization techniques. The excellent capability of PDA-SP@capillary in masking silanol groups and maintaining a highly robust EOF mobility was verified. Additionally, the parameters of sulfonation affecting the EOF mobilities were thoroughly examined. The obtained optimum SPD-coated column offered the anticipated highly pH-independent and high-strength cathodic EOF, which is essential for enhancing the CE separation performance and improving analysis efficiency. Consequently, the developed SPD-coated capillaries enabled successful high-efficiency separation of aromatic acids and nucleosides and rapid cyclodextrin-based chiral analysis of racemic drugs. Moreover, the SPD-coated columns exhibited a long lifetime and demonstrated good intra-day, inter-day, and column-to-column repeatability.