Preparation Of Three Dimensional Polyacrylic Acid/Graphitic Carbon Nitride Composite Hydrogel And Its Application In The Separation Of Hemoglobin

Protein is closely related to all kinds of life activities,and it is one of the most important research objects in life science.The establishment of efficient methods for protein purification is the basis of protein engineering.As a potential adsorbent,graphite carbon nitride(g-C3N4)has not been widely applied to the pretreatment of biological samples.In this work,the composite material consisting of graphite carbon nitride and polyacrylic acid(PAA)was used as an adsorbent for protein separation and purification,building a new method for the separation and enrichment of hemoglobin.In the first chapter,the proteins and hemoglobin were briefly introduced,and the importance and some common methods for protein isolation and purification were discussed.Then the research background,synthesis methods and important applications of graphite carbon nitride were introduced.In the second chapter,PAA/g-C3N4 composite hydrogel were prepared and characterized.The g-C3N4 was prepared by thermal polymerization of melamine,and the PAA/g-C3N4 composite hydrogel was synthesized via in-situ polymerization of g-C3N4 and acrylic acid with the help of initiation agent and cross-linking agent.The as-prepared composite hydrogel was characterized by Fourier transform infrared spectrometry,scanning electron microscopy,thermogravimetric analysis and Zeta potential.In the third chapter,PAA/g-C3N4 composite hydrogel was used as an adsorbent for selective extraction of hemoglobin.The theoretical maximum adsorption capacity was calculated to be 3333.3 mg g-1 according to the Langmuir adsorption model.The adsorbed hemoglobin could be eluted by Tris-HCl buffer solution at pH 8.9,giving rise to an elution efficiency of 85%.Circular dichroism spectra showed that the conformation of the recovered hemoglobin had not changed,indicating the PAA/g-C3N4 composite hydrogel has good biocompatibility.A new method for extracting hemoglobin from human whole blood samples was established.The result of SDS-PAGE demonstrated that a higher purity of hemoglobin could be obtained by using this method.