Recycling Biomass Of Water Pollutant Ulva Prolifera

Eutrophication is a common and huge ecological challenge faced by mankind worldwide,especially green tide pollution.Ulva prolifera macroalgae blooming(green tides)caused by eutrophication seriously affected the marine ecological environment.Its rapid proliferation not only shades the sun and affects the growth of marine organisms,but also consumes oxygen in the water and deteriorates water quality.Therefore,how to deal with the large amount of Ulva prolifera produced in the water has become a new challenge for us.At present,Ulva prolifera is mainly used to make fertilization,aquaculture feed and other products which has poor market competitiveness and low added value.There are few studies on high value-added products.Recently,algae polysaccharides have become one of the research hotspots due to its good biological activity.Therefore,the current research focus on the extraction,purification,chartacterization,and intelligent biomanufacturing of Ulva prolifera polysaccharides for potential biomedical application.The main research is mainly divided into four parts:1.Extracting polysaccharides from Ulva prolifera by short-time high-pressure water extraction.The extraction conditions of Ulva polysaccharides were optimized by single factor experiments of extraction time,sodium carbonate concentration and solid-liquid ratio aiming at the maximization of polysaccharides molecular weight and yield.The extraction conditions were further optimized by using response surface methodology.The best extraction conditions were: extraction time of 26 min,Na2CO3 concentration of 1.3% and solid-liquid ratio of 1/10.The molecular weight and yield of polysaccharides obtained under the optimal conditions were 5.23×106 g/mol and 8.1% w/w,respectively.Then the crude polysaccharides from Ulva prolifera were purified by DEAE-52 cellulose column chromatography and Sephadex-G100 dextran chromatography column to obtain purified polysaccharides.2.Physical and chemical analysis of the crude polysaccharides and purified polysaccharides of Ulva polysaccharides showed that the proportions of uronic acid in the polysaccharides were(39.42±0.7)% and(40.15±0.9)%,w/w,respectively.The proportions of sulfate in polysaccharides were(15.40±0.3)% and(14.97±0.4)%,w/w.The molar mass of the polysaccharides is around 105 g/mol.The monosaccharide mainly composed of galactose,glucose,xylose and mannose.FTIR analysis showed that Ulva polysaccharides are sulfated anionic polysaccharides.Both the crude Ulva polysaccharides and purified polysaccharides have reducing power and the ability to remove hydroxyl radicals,superoxide radicals and DPPH free radicals,showing a concentrationdependent response.The antioxidant capacity of the purified polysaccharide is slightly stronger than that of Ulva crude polysaccharide.3.Through the establishment of the H2O2 stress model on NIH 3T3 fibroblast cells,it was found that the effective stimulating concentration of H2O2 was 0.35 mmol/L,and the optimal concentration of crude polysaccharides and purified polysaccharides within the experimental range was 20 mg/m L.Through biochemical analysis of cells,it is concluded that Ulva polysaccharides have significant effects on the expression of MDA,SOD,ROS,CAT and GPx in cells,and the addition of ulva polysaccharides can effectively help cells resist oxidative stress damage.Moreover,it was confirmed by Western blot experiments that the expression of NF-κB gene in cells treated with polysaccharides was significantly reduced,especially the effect of polysaccharides after purification was the most obvious.4.The Ulva polysaccharide was in-situ adsorbed onto the 3D bioprinted nanocellulose scaffold to form a new composite material.The biocompatibility of the composite scaffold was evaluated by 3D cell culture,immunostaining and confocal imaging,and fluorescence microscope imaging.Results showed that it has good biocompatibility and no obvious cytotoxicity.The research explored and developed a novel method of extracting Ulva prolifera polysaccharides,and the extracted polysaccharides have excellent ability to protect cells against oxidative stress damage.This provides a new way to effectively solve the problem of Ulva prolifera waste accumulation caused by eutrophication.This approach has the potential for high value-added application and has great potential market demand.However,the biocompatibility of Ulva prolifera polysaccharides and its composite scaffold composed of nanocellulose needs to be further understood,so as to explore more specific reasons that affect the antioxidant capacity of Ulva prolifera crude polysaccharides and purified polysaccharides,and achieve their potential applications in the field of biomedicine.