Peptides-modified cellulose microspheres for adsorption of ochratoxin A: Performance and mechanism

In this study, peptides with ochratoxin A (OTA) recognition and adsorption capability were designed, among which lysine, histidine, arginine and tyrosine were crucial. Peptide CYFRFYSNLHPK showed the strongest affinity for OTA (Ka = 1.74 x 105 M- 1). Theoretical calculations revealed that the differences in the affinity of peptides for OTA were attributed to differences in the type, number and position of amino acids residues. Peptides were conjugated with porous cellulose microspheres to form peptide-modified pretreatment materials (Pep-MPA-RCMs) for adsorption of OTA. The morphology and composition of the prepared Pep-MPA-RCMs were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray diffraction. The effects of pH, adsorption time, initial concentration and temperature on the adsorption process were investigated. The adsorption performance was correlated with the pseudo-second order kinetic and Sips adsorption isotherm model. Thermodynamic studies further proved that the adsorption was exothermic and the prepared Pep-MPA-RCMs showed the maximum adsorption capacity of 9.87 mg/g for OTA at 25 degrees C. A simple adsorption column for OTA was prepared by using Pep-MPA-RCMs as filler material, which still maintained more than 80 % of the removal rate after five consecutive adsorption-elution cycles. The prepared pretreatment material was successfully applied to remove OTA in real samples and was a promising adsorbent for practical applications.