We found that the anticancer peptide leuprorelin strongly binds to the carcinogenic ochratoxin A (OTA) in non-aqueous solutions, and this finding has been utilized for the efficient solid-phase extraction of OTA from non-aqueous solutions using the peptide anchored onto surfaces of mesoporous polymers. The extraction was applicable even with a heavily contaminated coffee extract, and the quantification satisfied the recommendation of the Codex Alimentarius Commission, with a good detection sensitivity as comapred with its limit of detection (LOD, Anal. Chem. 1999, 71, 2672‒2677). The intermolecular association was analyzed based on thermodynamics and computational calculations, and we concluded that the good extraction comes from an excellent binding between the surface-bound leuprorelin and OTA with an equilibrium constant of 2.2 × 108 M‒1 at 273 K (dissociation constant Kd = 4.5 nM) when the peptide leuprorelin was functionalized into a mesoporous polymer.
In addition, we also found that the association was reversible even at the solid-liquid interfaces: With acetonitrile as the solvent, the strong association between the peptide and mycotoxin was achieved, while the use of aqueous phosphate buffer (PBS) as an eluent or solvent led to dissociation of the associated form. This enabled us to achieve an efficient capture of OTA from homogeneous solution by the peptide functionalized onto the surfaces of polymers, and this was successfully followed by releasing OTA by switching the eluent from acetonitrile to PBS. We also confirmed that the performance of the newly prepared system was much better than those using a conventional commercially available immunoaffinity column in acetonitrile. Such a good reversibility of capturing/releasing mycotoxins along with the excellent binding as analyzed by the thermodynamics has been achieved for the first time using non-aqueous eluent/solvent system.
This work is published in Chemical Communications, the journal of the Royal Society of Chemistry (RSC) for urgent communications of outstanding significance from across the chemical sciences, on 23rd September 2022 (Chem. Commun. 2022, 58, 12106‒12109). Because the system was free from deactivation in organic solvents with superior repeatability for the extraction, this finding will open a new way of non-aqueous "peptide-based solid-phase extraction" to alternate conventional immunoaffinity methods.
Published on 23rd September 2022
Last modified on 1st October 2022