PORPHYRIN NANOPARTICLES WITH HIGH MAGNETITE CONTENT AS A SELECTIVE SORBENT FOR ANGIOTENSIN

SOTO, S; DABAS, P; CARBALLO R; VIZIOLI NM

Mendoza

Simposio; 24th Latin-American Symposium on Biotechnology, Biomedical, Biopharmaceutical, and Industrial Applications of Capillary Electrophoresis and Microchip Technology- LACE 2018; 2018

Several kinds of magnetic nanoparticles (MNP) have been produced from both natural and synthetic polymers with the intention to incorporate groups on the surface or to treat their surface to perform, for instance, selective separations1. For example, the presence of a metal ion in the porphyrin core provides selectivity to nanoparticles when it is covered with such compounds. In the present work, the interaction of MNP with a model peptide, such as angiotensin I, was thoroughly evaluated. The MNP were synthesized by co-precipitation of iron salts in alkaline medium and inert atmosphere2. Particles were subsequently coated with Cu(II)-porphyrin in organic medium3. Bare and modified MNP (CuPP@MNP) were characterized by means of vibrating sample magnetometery, microscopy, zeta potential, UV-visible and Fourier transform infrared spectroscopy. To assess the interaction of MNP with angiotensin I, an exactly measured amount of MNP was kept in contact with peptide solutions. The adsorption assays were performed at pH that ranged from 2.5 to 10.0. MPN were separated from solution with an external magnet and re-dispersed after magnet removal. Aliquots of supernatant were taken at different times and analyzed by CE in a P/ACE MDQ system, using a 50 mM sodium phosphate solution, pH 7.0, as background electrolyte. Different desorption conditions were tested including pH of the elution buffer, acetonitrile percentage, sodium chloride content, and concentration of imidazole. Quantification of angiotensin I demonstrated that differential selectivity and a high peptide adsorption rate (over 80%) was obtained at pH 7.0. Angiotensin I adsorption onto bare MNP at pH 5.0 could be explained by presence of an aspartic acid residue on its amino acid sequence which confers affinity to the iron present in the MNP. The interaction between angiotensin I and CuPP@MNP fitted a Langmuir-Freundlich model during the first 30 min period of contact (Kd: 3.31e-7 mg/mL, qm: 0.92 mg/mL, n: 2.86). After that, the adsorption isotherm followed the Freundlich model (Kf: 3.29 mg/mL, n: 5.34), indicating that interactions of different intensity would be present.