| Summary: | 碩士 === 國立臺灣科技大學 === 高分子工程系 === 91 === The paper was divided into four parts to study. Section 1 investigated the morphology and permeability of PAN/PVDF blends membrane. In section 2, blood compatibility of PAN /PVDF blend membrane was studied. Section 3 investigated the hemocompatibility of PAN membrane surface-immobilized with chitosan/heparin, albumin and collagen conjugate. Finally, the blend hollow fiber membranes were spun using PAN91, PAN82, and PAN73.
Polyvinylidine fluoride (PVDF) and polyacrylonitrile (PAN) of various ratios were dissolved in dimethylformamide (DMF) and cast into membranes via the phase inversion technique. The characteristic and structure of PAN/PVDF membranes were examined using scanning electron microscope (SEM), Fourier transform infrared (FTIR), elemental analysis (EA). The contact angle, equilibrium water content (EWC), porosity, and mechanical properties were also determined. The permeation performance evaluated included pure water permeability (PWP), degree of retention (R%) and diffusion properties measurements.
The blood compatibility was evaluated by measuring the activated partial thrombin time (APTT), prothrombin time (PT), fibrinogen time (FT), and thrombin time (TT), the adsorption of the blood proteins, the activation and adhesion of platelet, and the thrombus formation. In addition, Chitosan (CS)/heparin (HEP) polyelectrolyte complex (PEC), albumin, and collagen were covalently immobilized onto the surface of polyacrylonitrile (PAN) membrane. The effect of surface modification on the protein adsorption and platelet adhesion, metabolites permeation and anticoagulation activity of the resulting membrane was investigated. Surface characterization such as water contact angle, and X-ray photoelectron spectroscope (XPS) were performed.
The results show that water contact angle increased and EWC decreased with the PVDF content in the membrane, suggesting the increase in the hydrophobicity. The tensile strength of blend membrane was lower than that of PAN membrane, but the elongation of blend membrane was higher than that of PAN membrane. With increasing PVDF content, the PWP of the blend membrane increased while the R% decreased. The molecular weight cut-off (MWCO) increased with the PVDF content, and ranged between 50 kD and 1500 kD. The permeability coefficient of the blend membrane increased with the hydrophilicity. By blending PVDF into PAN, the MWCO of the membrane can be varied in a wide range for various applications.
In addition, by blending PVDF to PAN can reduce the adsorption of protein and platelet and improve the blood compatibility of the membrane. The improvement in the blood compatibility of PAN/PVDF can be attributed to higher hydrophobicity and result in a higher ratio of human serum albumin (HSA) to human plasma fibrinogen (HPF) than pure PAN. Thus the degree of thrombosis and the adhesion of platelet decreased with the increase of the PVDF content in the membranes.
The immobilization of PEC, albumin and collagen caused the water contact angle to reduce, thereby indicating the increase in the hydrophilicity. Protein adsorption, platelet adhesion, and thrombus formation were all reduced by the immobilization of heparin (HEP) and albumin, and increased by immobilization of chitosan (CS) and collagen (COL). The results revealed that PEC-immobilizing and albuminized membrane can improve antithrombogenicity of PAN membrane, but chitosanized and collagenized will promote thrombus formation. Nevertheless, chitosan- and collagen-immobilizing PAN can improve biocompatibility.
In addition, the PEC-immobilized membranes can suppress the proliferation of Pseudomonas aeruginosa. In vitro cytotoxicity test showed leachable substance released was below cytotoxic level. The pure water permeability (PWP) results show little variation due to PEC-immobilization. Thus PEC-immobilization can endow the PAN membrane hemocompatibility and antibacterial activity while retaining the original permeability.
Keypoint：hemodialysis, blend, immobilization, pure water permeability, MWCO, permeability, hemocompatibility, antibacterial activity, cytotoxicity, hollow fiber membrane.
|
|---|
