Natural Polysaccharide-Based Antibacterial Surface Functionalization On Medical Filter Materials

Filter materials have wide applications in the medical and healthy areas.However,microbial contamination on the surface of filter materials occurs frequently,causing serious hospital-acquired infections(HAIs),which will not only worsen the condition of patients,but may cause public health incidents.This thesis is aiming to solve the urgent problem mentioned above by antibacterial surface functionalization of two common filter materials.The first part mainly aims at the surface modification of the microfiltration(MF)membrane.As a common solid-liquid separation technology,microfiltration is widely used in medical and health fields.In this chapter,oxidized dextran(ODex)was selected as the macromolecular backbone and was grafted onto the MF membranes with large pore size(3 μm).Then,polyhexamethylene guaidine(PHMG)was introduced onto the MF membrane by Schiff base reaction.The zeta potential of the MF membrane verified that the modified MF membranes had a higher zeta potential.Driven by gravity,the modified MF membrane showed high bacterial filtration efficiency(BFE)for E.coli(99.9%)compared to the pristine MF membranes(20.9%),and the adsorption efficiency of MF membranes for endotoxins had been increased from 37.4%to 59.5%.Meanwhile,the MF membranes with 3 μm pore size had a high water flux of 5255 L/(h·m2),showing the efficient water treatment ability.In addition,the modified MF membranes had better sterilization ability due to the introduction of PHMG,killing the bacteria captured by MF membranes.The second part is the antibacterial surface functionalization of polypropylene(PP)melt-blown nonwovens,which is used to filter the aerosols of bacteria.The surface functionalization strategy of PP melt-blown nonwovens was based on natural polysaccharides and PHMG grafting.The BFE for S.aureus was increased from 74.6%to 81.0%after modification,and the mortality of S.aureus on the surface was increased from 17.8%to 92.0%.The modified PP melt-blown nonwovens showed great antibacterial ability.To sum up,based on oxidized polysaccharides as macromolecular backbones,two typical medical filter materials,MF membrane and melt-blown nonwovens,were modified with high-efficiency wide-spectrum antibacterial agent PHMG to solve the problem of microbial contamination.The bacterial filtration efficiency and antibacterial ability had been increased significantly.This dissertation provides new strategies for the development of antibacterial medical filter materials combating hospital-acquired infections.