Polydopamine-Assisted Rapid One-Step Immobilization of L-Arginine in Capillary as Immobilized Chiral Ligands for Enantioseparation of Dansyl Amino Acids by Chiral Ligand Exchange Capillary Electrochromatography

Abstract

Herein, a novel L-arginine (L-Arg)-modified polydopamine (PDA)-coated capillary (PDA/L-Arg@capillary) was firstly fabricated via the basic amino-acid-induced PDA co-deposition strategy and employed to constitute a new chiral ligand exchange capillary electrochromatography (CLE-CEC) method for the high-performance enantioseparation of D,L-amino acids (D,L-AAs) with L-Arg as the immobilized chiral ligand coordinating with the central metal ion Zn(II) as running buffer. Assisted by hydrothermal treatment, the robust immobilization of L-Arg on the capillary inner wall could be facilely achieved within 1 h, prominently improving the synthesis efficiency and simplifying the preparation procedure. The successful preparation of PDA/L-Arg coatings in the capillary was systematically characterized and confirmed using several methods. In comparison with bare and PDA-functionalized capillaries, the enantioseparation capability of the presented CLE-CEC system was significantly enhanced. Eight D,L-AAs were completely separated and three pairs were partially separated under the optimal conditions. The prepared PDA/L-Arg@capillary showed good repeatability and stability. The potential mechanism of the greatly enhanced enantioseparation performance obtained by PDA/L-Arg@capillary was also explored. Moreover, the proposed method was further utilized for studying the enzyme kinetics of L-glutamic dehydrogenase, exhibiting its promising prospects in enzyme assays and other related applications.

Recent Advances in Separation and Analysis of Chiral Compounds

“…The developed method gave low LODs of 0.015−0.90 μg mL −1 and good recovery of 80.6%−117.3% for the enantiomers of catechu herbs and salbutamol in real sample matrixes. 95 CD derivatives were also used as the chiral functionality units to modify other achiral materials to obtain novel CSPs for CEC. Sulfydryl-β-CD was functionalized onto the gold nanoparticles−graphitic carbon nitride to obtain chiral CSP (CD-GNPs-g-C 3 N 4 ).…”

“…β-CD and l -phenylalanine ( l -Phe) were also coupled with zeolite silica nanoparticles as the CSP of open-tubular capillary column for CEC. The developed method gave low LODs of 0.015–0.90 μg mL –1 and good recovery of 80.6%–117.3% for the enantiomers of catechu herbs and salbutamol in real sample matrixes …”

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

“…Benefiting from the strong substrate-independent surface adhesive properties, versatile reactivity, relatively simple fabrication processes similar to physically adsorbed coatings, and favorable stability as covalent coatings, mussel-inspired polydopamine (PDA) and its derivative materials are highly suitable for various surface modification applications [16][17][18], including the inner wall modification of fused-silica capillaries [19]. Several functional PDA coated columns have been developed for CE or capillary electrochromatography (CEC) separations in different application fields [20,21], including the separation of small organic molecules [22][23][24][25], protein separation [26,27], chiral separation [28][29][30][31], etc. However, most existing PDA-based capillary modification strategies in CE, involving alkaline pH-induced oxidative polymerization of dopamine, often exhibit a poor surface masking effect and require an extended time ranging from over 20 h to several days, thus limiting reproducibility and practicality.…”