Assessment of the binding performance of histamine‐imprinted microspheres by frontal analysis capillary electrophoresis

Abstract

Frontal analysis capillary electrophoresis was used to evaluate the binding performance of molecularly imprinted microspheres (MIM) toward its template histamine and analogs at pH 7, and compared to the high performance liquid chromatographic method. In both methods, batch binding was employed and the binding parameters were calculated from the measured concentration of unbound amine analytes and afforded comparable histamine equilibrium dissociation constants (K ∼ 0.4 mM). FACE was easily carried out at shorter binding equilibration time (i.e. 30 min) and without the need to separate the microspheres, circumventing laborious and, in the case of the system under study, inefficient sample filtration. It also allowed for competitive binding studies by virtue of its ability to distinctly separate intact microspheres and all tested amines which could not be resolved in HPLC. K 's for nonimprinted (control) microspheres (NIM) from FACE and HPLC were also comparable (∼ 0.6 mM) but at higher histamine concentrations, HPLC gave lower histamine binding. This discrepancy was attributed to inefficient filtration of the batch binding samples prior to HPLC analysis resulting in an over-estimation of the concentration of free histamine brought about by the presence of unfiltered histamine-bound microspheres.

Room temperature synthesis and binding studies of solution‐processable histamine‐imprinted microspheres

“…The FACE analysis accounts for the electrostatic interactions between the negatively charged microspheres and the positively charged analytes. Among the different analytes, tryptamine carries similar charge as histamine, followed by imidazole, while L‐histidine has almost neutral charge (Figure S7) . These results indicated that even selective binding is observed for PCP‐M80 and CTP‐M80, tryptamine possessing similar charge and size as histamine can have pronounced non‐specific binding to the imprinted cavities of the microspheres (PCP‐M80 and CTP‐M80).…”

“…The parameters employed for FACE analysis were obtained from our previous study . The control of capillary temperature is important in optimizing separations; in our hands, all the FACE experiments were carried out without modifications implemented to reduce Joule heating.…”

Studying molecular interactions via capillary electrophoresis and microscale thermophoresis: A review

“…It has been found a strong dependence of the binding parameters with the ionic strength and also that the concentration of polymeric adjuvant significantly modifies the ionic strength of the formulation, the extent of which can be estimated and corrected [58]. The applications of CE-FA [47,52,55,57,[145][146][147][148][149][150][151][152][153][155][156][157][158][159][160][161] and FACCE [58][59][60]154] are summarized in Table 3.…”