Moving affinity boundary electrophoresis and its selective isolation of histidine in urine

Abstract

Affinity analysis is a key biotechnique used in the fields of biology and biomedicine. Herein, we advanced the concept of moving affinity boundary (MAB) using metal ion Ni(II) and histidine (His) as the model inorganic ion and ligand, respectively, developed the simple method of MAB affinity capillary electrophoresis (MAB-ACE), and carried out the relative experiments. The experiments manifested that (a) an MAB could be created with the model metal ion and ligand; (b) the MAB-ACE could specifically capture His rather than other amino acids, or numerous metabolites in human urine; and (c) the capture had the merits of simultaneous focusing and separation to the target metabolite of His. It was further revealed that the specificity of MAB-ACE was originated from the selective affinity interaction and the effective control of affinity conditions. The analyses of His in raw urine by the MAB-ACE are in agreement with those via the standard amino acid analyzer, indicating the reliability of the developed method. Additionally, the MAB-ACE with UV detector had good sensitivity (LOD = 43 ng mL(-1), S/N = 3), 1.0-150 microM linearity and <5% intra-/inter-day variations. The novel method has an evident potential application for capture of a target metabolite in complex biological sample.

Fluorescent/luminescent detection of natural amino acids by organometallic systems

“…Therefore, enantioselectivity is one of the most important goals for the sensing of organic substances [190][191][192][193][194][195][196][197][198], because biological activity is strictly correlated with stereochemistry. Although some enantioselective methods based on capillary electrophoresis [199][200], voltammetry [201], colorimetric methods [202][203][204] etc. have been proposed, there are examples of enantioselective fluorescence sensors [205][206].…”

Equivalence‐point electromigration acid–base titration via moving neutralization boundary electrophoresis

“…Third, the concept of moving chelation boundary has been applied for the illumination on mechanism of EDTA-based sample sweeping of heavy metal ions in CE [24,27]. Fourth, the newly developed ideal of MAB has been used for the selective capture of a target metabolite in complex biomatrix of human urine [28]. This paper for the first time shows that (i) the concept of MRB can be used to design a novel acid-base titration of EABT via the MNB formed with H 1 and OH À , (ii) the length of boundary movement in a single run of EABT as a function of running time, (iii) the length, which is in proportion to the natural logarithm concentration of reactant (HCl) under the condition of constant concentration base, can be used to determine the concentration of reactant and (iv) the EABT has these characteristics with similar precision to that of CE or HPLC, strong resistance against the influence of indicators with different pK In values, and constant equivalence-point electromigration titration between H 1 and OH À .…”

“…In 1990s, the idea of equivalent electromigration reaction between H 1 and OH À was developed for protein concentration [23]. During the last decade, Cao et al [24][25][26][27] advanced systemic theories and methods of MRB, such as moving precipitate boundary [24], neutralization boundary (MNB) [24][25][26], chelation boundary (MCB) [24,27] and affinity boundary [28]. Supporting Information Fig.…”

Recent advances in amino acid analysis by capillary electrophoresis

“…Meng et al described the development of the concept of moving affinity boundary in affinity CE (MAB‐ACE) using a metal ion [Ni(II)] for selective detection of His 16. In the optimized conditions, the sample was diluted in the electrolyte (50 mM, pH 6.0, Na 2 HPO 4 ‐NaH 2 PO 4 buffer with 1.0 mM NaCl); then the capillary was filled with the sample.…”