Fluoridized iron phosphate as a novel adsorbent for selective separation/isolation of cytochrome c

Fluoridized iron phosphate (F-FePO) is prepared via a hydrothermal protocol and characterized by means of ⁵⁷Fe M?ssbauer spectra, Fourier transform infrared, and surface charge analysis. For the first time, F-FePO is used as an adsorbent for the adsorption of proteins, which exhibits favorable selectivity toward cytochrome c (cyt-c) in the presence of acidic and neutral proteins under controlled experimental conditions. At pH 10.5, an adsorption efficiency of 100% is achieved for 60 mg L⁻¹ cyt-c in 1.0 mL of sample solution using 6.0 mg F-FePO. The adsorption behavior is consistent with the Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 37.59 μg mg⁻¹. The retained cyt-c on F-FePO could be readily collected by 0.1 mol L⁻¹ Na₂CO₃–NaHCO₃ buffer (pH 10.5), deriving a recovery of 100%. Circular dichroism spectra indicate no conformational change for cyt-c after the adsorption and desorption processes, demonstrating the favorable biocompatibility of the fluoridized iron phosphate. F-FePO is employed for the selective isolation of cyt-c from a spiked human whole blood, achieving satisfactory results by assay with SDS-polyacrylamide gel electrophoresis and native polyacrylamide gel electrophoresis.