Preparation And Properties Of Sugar-based Biomass Carrier

Carrier materials,including inorganic materials,organic polymer materials,and inorganic-organic hybrid materials,are widely used in medical,catalytic,and fine chemical industries.Sugar polymers and their derived carriers can not only overcome the incompatibility of traditional carrier materials such as non-biodegradability,poor biocompatibility and poor reusability,but also be easy to realize industrialization,reduce human dependence on chemical petroleum products,and comply with the concept of green chemistry.Biomass-based sugar-based carriers have the advantages of abundant reserves,good biocompatibility,non-toxic side effects,and good biodegradability.Biomass polymers contain a large number of hydroxyl groups to provide modifiable groups for improving the adsorption capacity,ligand performance and selectivity of the materials,and they have become new directions and hotspots for the research of certain carrier materials.Under the background of this research,this paper designed and synthesized different types of carriers and applied them to the fields of medicine and catalysis.The specific contents are as follows:1.Preparation,Structure and Properties of Amphiphilic Xylan-cholic Acid ConjugatesA novel amphiphilic biopolymer was synthesized by incorporating hydrophobic segment cholic acid?CA?into hydrophilic segment carboxymethyl xylan?CX?through coupling agent.Structural characteristics and self-assembly behaviors of the amphiphilic conjugates in aqueous solution were investigated in detail.Results showed that the conjugates provided monodispersed self-assembly micelles in distilled water,with average diameters in the range of 90-135 nm,depending on the DS of CA.TEM and AFM images proved that the self-assembly micelles were spherical.The micelles were covered with negatively charged carboxymethyl xylan shells,exhibiting Zeta potential about-38 mV.The aggregation concentration?CAC?of the conjugate(0.0079-1.25×10^-2g/L)was closely related to the DS of CA and solution pH.Moreover,CX-CA nanoparticles were sensitive to the pH of release media.The cellular uptake of DOX-loaded CX-CA nanoparticles was better than that of free DOX,and thus CX-CA nanoparticles can be used as a new carrier for antitumor drugs delivery.2.Preparation of Xylan-based Porous Hydrogel Supported Palladium Catalyst and Its Catalytic Performance for Carbon-carbon Coupling ReactionHemicelluloses based hydrogel was prepared with AM-g-XH,it owns abundant N and O elements,which is contributed to the coordination of noble metal ions.Porous structures of hydrogels can supply abundant space for the noble metal nanoparticles.AM-g-XH-MAA-Pd was prepared by dispersing the Pd²⁺in the hydrogel and then reduced with NaBH₄.AM-g-XH-MAA-Pd was applied in catalysis for the Suzuki reaction,and the impact of the solvents,base,reaction time,reaction temperature,catalyst dosages,scopes of the substrate and catalyst recycling times were also investigated in the reaction.The experiment results showed that the yield of Suzuki reaction can reach 99.35%under the system of AM-g-XH-MAA-Pd,ethanol,K₃PO₄ at 70 ^oC and for 5h.There were no significant loss of catalytic activity and outflow of Pd nanoparticles after being reused five times,and AM-g-XH-MAA-Pd can be recycled in simple method.In summary,AM-g-XH-MAA-Pd as a renewable heterogeneous catalyst showed better performance in these multicomponent reactions not only in terms of activity but also be environment-friendly.On the basis of the above research.Hydrogel,prepared with acrylamide graft hemicelluloses?AM-g-XH?and,was impregnated in Pd²⁺before reduced to get AM-g-XH-NIPAM-Pd catalyst.The abundant N and O elements of of hydrogels is contributed to the coordination of noble metal ions and porous structures of hydrogels can supply abundant space for the noble metal nanoparticles.AM-g-XH-NIPAM-Pd was applied in catalysis for the Suzuki reaction,and the experiment results showed that the yield of Suzuki reaction can reach 100%under the system of AM-g-XH-NIPAM-Pd,ethanol,K₂CO₃ at 70 ^oC and for 3 h.There were no significant change of porous structures and outflow of Pd nanoparticles after being reused five times and the yield can reach 99.13%,and AM-g-XH-MAA-Pd is consistant with the requirements of green chemistry,it has a promising prospect prospect in organic synthesis and biomass high value utilization.3.Preparation of Sugar-based Carbon Quantum Dots Supported Palladium Catalysts and Its Catalytic Performance for Hydrogenation of OlefinsSugar-based carbon dots was prepared with glucosamine hydrochloride through the one-step hydrothermal route.Pd@CQDs-2 was prepared by dispersing the Pd²⁺in the carbon dots solution and then reduced with Na BH₄.Pd@CQDs-2 was applied in catalysis for the Hydrogenation reaction,and the impact of reaction temperature 40^oC¹00^oC,reaction time1⁴h,catalyst dosages,pressure of the hydrogen,scopes of the substrate and catalyst recycling times were also investigated in the reaction.The results showed that the glucosamine carbon dots own abundant electronic defects,which is helpful for the coordination of noble metal ions and the dispersion and the size control of noble metal nanoparticles.The yield of hydrogenation reaction can reach 100%under the optimal condition for hydrogenation reaction:The Pd@CQDs-2 catalyst was 8.7mg,reaction temperature was at 80^oC and reaction time was 1h.In summary,Pd@CQDs-2 as a renewable catalyst showed better performance in these catalytic reactions not only in terms of their high activity but also be environment-friendly.