| Biomedical polymer materials are one of the most promising functional materials, which have been extensively studied. However, poor biocompatibility with human body of most conventional biopolymer materials will cause a series of adverse biological effects, such as thrombosis and the potential inflammatory reactions. It is generally accepted that the surface modification is one of the most important methods to improve biocompatibility of material beacuase the surface performance of biomedical polymer materials determined the biological reaction between blood and tissue. At present, immobilizing the bioactive biomacromolecules such as polysaccharides on the surface material is one of the most effective ways to improve its biocompatibility.In this work, Cantharellus cibarius polysaccharides were extracted from Cantharellus cibarius Edode, and sulfated polysaccharides were prepared. Then, sulfated polysaccharides were immobilized on the surfaces of cellulose acetate membrane by layer-by-layer (LbL) self-assembly mothod. The surface wettability^ blood compatibility and antimicrobial biological activity of the modified materials were studied. The main contents and results are as follows:(1) Four extract methods were used in the experiment to extract the Cantharellus cibarius polysaccharides, and their yield were as follows:hot water extraction with the yield of 9.41%, ultrasonic enhanced extraction 8.99%, cellulase extraction 8.58%and ultrasonic-assisted cellulase extraction 9.96%, respectively. The ultrasonic-assisted cellulase extraction was chosen due to the highest polysaccharides extraction yield. Then the single factor, Plackett-Burman experiment and response surface methodology were adopted to optimize the extraction conditions of ultrasonic-assisted cellulase extraction. The optimal technological parameters were as follows:solid-liquid ratio 1:46 (g/mL), pH5.5, ultrasonic power 210 W, enzymatic hydrolysis time 68 min, enzyme dosage 7.5 IU/g, enzymatic hydrolysis temperature 50℃, ultyasonic time 30 min and ultrasonic temperature 50℃, respectively. Under these conditions, the crude polysaccharides yield was 11.96%.(2) The polysaeeharides from the Cantharellus cibarius were treated through deproteinization, decoloration and dialysis for removing small moleeules, then was fractionated by a DEAE-52 cellulose and SephadexG-100 column chromatography, yielding two main subfractions (CP-1A and CP-3A). Polysaccharide purity, molecular weight and its primary structure were determined. UV-Vis spectra showed that both CP-1A and CP-3A were no protein and nuclear acid. FTIR spectra demonstrated that both of them revealed the typical characteristic absorption of polysaccharides and contained pyranoid ring and exist α-glycosidic bond and β-glycosidic bond. HPLC results showed that CP-1A was composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, xylose, arabinose, fucose and their molar ratio was about 8.03:3.36:1:1.15:17.41:7.59:3.05:1.59:6.59; CP-3A was composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, xylose, fucose and their molar ratio was about 53.34:4.19:9.98:5.40:57.9:27.01:1:5.73.(3) CP-1A was sulfated using sulfuric acid method to obtain sulfated polysaccharide (SCP), the replace degree of sulfur is 0.87. The antioxidant activity test of Cantharellus cibarius polysaccharides before and after modification indicated that SCP can improve the scavenging activities of OH free radical and DPPH free radical. The anticoagulant testing results showed SCP has good anticoagulant activity, which worked by affecting intrinsic pathway coagulation system, extrinsic pathway coagulation systerm and common pathway coagulation systerm to prolong activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) of plasma effectively.(4) Chitosan and SCP were alternate deposited to the surface of cellulse acetate membrane through LbL method. The growth modes and the morphologies of LBL multilayers were characterized, and the surface biocompatibility and antibacterial activity were investigated, respectively. The test results showed that the growth occurred on suface of the cellulse acetate membrane was uniform and continuous. The average thickness, the surface root-mean-squars (RMS) roughness of the CS/SCP multilayers gradually increased as the LBL self-assembly proceeded. The water contact angle measurement results showed that the modified cellulse acetate membrane surface became more hydrophilic. The test results of APTT, TT and PT showed that modified cellulose acetate membrane had a certain anticoagulant function. Moreover, the hemolysis testing results demonstrated the modified cellulse acetate membrane had a better blood compatibility. When a (CS/SCP) 10 multilayer was formed on the the cellulse acetate membrane surface, the hemolysis rate of material is only 0.4%. In addition, the degree of growth inhibition for bacterial (E. coli and S. aureus) increased with the increasing number of bilayers, and the antibacterial activity was better when CS was in the outermost layer compared to that of SCP was in the outermost layer. |
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