Study On Preparation And Structure-Activity Relationship Of Xylan-based Bio Functional Materials By-product From Dissolving Pulp

Dissolving pulp is a high-purity chemical pulp,in which?-cellulose accounts for up to90-98%.Therefore,after the lignocellulosic biomass are sent to the dissolving pulp mills,only cellulose is transformed into the final product,while lignin and hemicellulose are mostly incinerated or buried.In order to improve the utilization of these industrial by-products,this paper takes the industrial by-products from dissolving pulp mill as raw materials,on the basis of in-depth study of its structure and physical as well as chemical properties,chemically modifies it through methods including esterification and oxidation modification.Applications of modified xylan in drug delivery system and cosmetics are further explored.These results are listed here:(1)Xylan was the main component of the industrial by-products evidenced by FTIR and NMR test results.There was 9.6%(w/w)ash in the IBX,and Cu is the predominant metal element.XRD spectrum reflected that IBX had crystalline area,and DMSO/TBFA is the best solvent among all tested groups.(2)IBX was esterified in DMSO/TBFA by stearic acid under various conditions with degree of substitution from 0.34 to 1.54.Both FTIR and NMR results evidenced the successful esterification,and less crystalline was obtained after esterification.A pH-responsive SA-Xyl nanoparticle with loading function was fabricated by the means of dialysis.The average size of particle was 215 nm,loading efficiency and loading rate was64 and 3.2%,respectively.The release amount of the particles in conditions with pH=2.0and 11.0 were 53.8 and 43.6%in 24 h,respectively;Emulsifying ability of SA-Xyl was evaluated in a mixture of 95%H₂O and 5%MCT.The optimal addition amount of SA was0.05 g,and the obtained emulsion was stable with small particle size.(3)IBX was oxidized by NaIO₄ in different conditions with oxidation degree in the range of 0.40-0.83.Characterizations of FTIR and NMR suggested that xylan has been successfully oxidized,and DAX had stronger scavenging ability of DPPH free residue when the concentration of DAX was increasing.A skin care hydrogel was fabricated through reaction between DAX and gelatin.When glycerol and nicotinamide(NCA)were introduced with an appropriate amount,the gel with ideal mechanical and rheological property was obtained.This gel had an excellent NCA release pattern in an environment where skin pH is simulated,and it was effective against Yeast,Bacillus subtilis and Staphylococcus aureus.Good cell compatibility was proved by CCK-8 assay.Complex was obtained by reaction of DAX and phenylalanine(PA).The best reaction condition was DAX:PA=1:1,60?,8 h.The maximum excitation and emission wavelength was found at 362 and 444 nm,respectively.The fluorescence intensity of the DAX-PA aqueous was increased when the concentration of Al³⁺was increasing,while it was decreased when the concentration of Fe³⁺was increasing.(4)Sulfonation modification of IBX was performed in two ways:one-step method using SO₃.Py,and two-step method involving quaternization and modification with synthetic sodium aminotrisulfonate,successively.Sulfonated xylan from one-step synthesis had a lower degree of substitution.The product obtained from two-step method had a higher degree of substitution and a lower molecular weight than the former.Anticoagulant ability of the derivatives was evaluated by PT and APTT results.The products obtained by the two-step method had better anticoagulant effects and ABTS free radical scavenging ability,comparatively.