Study On The Graphite Carbon Nitride In The Separation And Purification Of Proteins

As a kind of important biomacromolecules, protein plays crucial role in various life activities. Rapid and efficient separation of proteins from complex matrices is of great importance for proteomics. In the present work, graphite carbon nitride is first used for protein separation and a solid-phase extraction procedure is developed for the separation/purification of hemoglobin. The results further expanded the application potentials of Graphite carbon nitride in the field of life sciences.In chapter 1, brief reviews are given to the significance, principles and methodologies of protein separation/purification In addition, the properties of graphite carbon nitride as well as its applications in various fields have been discussed.In chapter 2, a solid-phase extraction protocol for the selective separation/purification of hemoglobin (Hb) from human whole blood is developed by using graphite carbon nitride as the sorbent. Melamine of Triazine structure is used as the original material in the synthesis of carbon nitride. After thermal polymerization of Melamine at 550? for 4 h, yellow carbon nitride is obtained. The obtained carbon nitride is characterized by means of SEM, FTIR, XRD, UV/Vis spectroscopy and Zeta potential. The performances of carbon nitride in the adsorption/isolation of hemoglobin are thus investigated. At pH 8.0, an adsorption efficiency of 98% for 50 mg·L-1 hemoglobin in a 1.0 mL solution is achieved by using 5.0 mg of Graphite carbon nitride as sorbent. The adsorption of hemoglobin onto graphite carbon nitride fits freundlich adsorption model and the secondary reaction kinetics equation. The retained Hb could be readily recovered by using a B-R buffer of pH 4.0, giving rise to a recovery of 60%. Circular dichroism spectra indicated that the adsorption/desorption procedures pose no obvious effect on the conformation of Hb, showing favorable biocompatibility of the Graphite carbon nitride. The developed extraction protocol is thus used for the selective isolation of Hb from human whole blood. The results of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) indicate that high purity of hemoglobin is obtained.