Preparation of pH-controllable nanofibrous membrane functionalized with lysine for selective adsorption of protein

Abstract

A pH-controllable electrospun nanofibrous membrane (NFM) was successfully fabricated by functionalizing polyacrylonitrile (PAN) NFM with lysine (LYS) for selective adsorption of protein. Due to the introduction of similar α- amino acid structure to PAN NFM, the surface charges of the obtained PAN-LYS NFM can switch via changing the pH value of adsorbate solution. Benefiting from the integrated merits of electrospun PAN NFM and LYS, PAN-LYS NFM exhibited excellent selectivity and reusability in protein adsorption. Pepsin and lysozyme were used as the model proteins, and the maximum adsorption capacity of pepsin and lysozyme were 425.49mgg−1 at pH 3 and 54.98mgg−1 at pH 8, respectively. Meanwhile, there was almost no adsorption of pepsin and lysozyme on the PAN-LYS NFM at pH 8 and pH 3, respectively, primarily owing to the strong repulsion of like charges between the NFM and protein. In view of this, PAN-LYS NFM could be used to realize the selective adsorption of protein by regulating buffer pH value based on the isoelectric point (pI) of protein. Furthermore, the protein adsorption can be also achieved via filtration by packing five layers of PAN-LYS NFM together and fixing them in a filter. More importantly, the PAN-LYS NFM can be regenerated and reused. The adsorption capacities of proteins kept relatively stable values within the four cycles, indicating that PAN-LYS NFM can meet the requirement of long service life. Therefore, PAN-LYS NFM exhibits a great potential in the applications of protein adsorption and purification.