Fabrication Of Membrane Absorber Based On Amphiphilic Carbonaceous Conjugates For Selective Endotoxin Clearance

Endotoxin,the lipopolysaccharide(LPS)component of the outer cell wall of gram-negative bacteria,It is continuously released into the environment during the process of bacterial apoptosis.The products prepared by Gram-negative bacteria are always contaminated with endotoxins,for this reason,these proteins must be as free as possible of endotoxin in order not to induce side effects when administered to animals or humans.In recent years,many different processes have been developed for the removal of endotoxin from biological products,adsorptive membrane chromatography with technological advances in both membrane filtration and fixed bed liquid chromatographypolymeric have gained more attention.In this study,amphiphilic carbonaceous particles(ACPs)derived from yeast cell were synthesized,which has multifunctional groups.Then,PEI and PMB were attached to the surface of the amphiphilic materials by covalent binding.functional ACPs blended with polyvinylidene fluoride(PVDF)to prepare PVDF affinity microfiltration(MF)membranes via phase inversion method.Comprehensive results of the investigations show that the optimal preparation technology of affinity membrane is: functional ACPs were added to DMF and the solutions were ultrasonically vibrated to render well-dispersed solutions,PVDF and PVP K30 was dissolved in the resulting ACPs solutions at 50 oC and stirred for 24 h to obtain a homogenous solution for casting,then spread onto a glass plate induced phase separation 30 s at room temperature,dipped into an ethanol/distilled water(1/4 by volume)coagulating bath.the optimal compositionof casting solution is: the mass ratio of functional ACPs and PVDF of 1:25,mass ratio of amount of PVDF and DMF of 9:50.The structure of these PVDF affinity membranes were characterized by SEM,and the performances of membranes were determined through the measurements of contact angle,pure water flux,mechanical properties and anti-fouling performance,the results indicated that the good dispersion of particles in the membrane was achieved after both ACPs and functional ACPs.the properties and structure of the blended membranes can be improved obviously,the permeability and mechanical properties are improved,protein absorption resistance as well as hydrophilicity are greatly improved.The prepared affinity membrane was used to removal endotoxin from protein-free solution,endotoxin content reduction from 6000 EU mL-1 to < 0.1 EU mL-1,the PVDF/ACPs-PEI and PVDF/ACPs-PMB in low ionic strength,ineutral or acidic solution were more effective.The PVDF/ACPs-PMB and PVDF/ACPs-PEI affinity membrane was used to removal endotoxin from different protein solution,exhibited better endotoxin adsorption and higher protein recovery rate in acidic protein solution than alkaline protein solution.