Preparation And Drug Loading Properties Of Ellagic Acid-modified Lignin Self-assembly

Lignin is the second largest biomass material after cellulose in the world.It has great potential biological value because of its complex structural units,such as guaiacol,syringyl and p-hydroxyphenyl units,which have antioxidant and antibacterial activities.As a natural polyphenol drug,ellagic acid(EA)also has anti-cancer,anti-inflammatory and other multi-activity characteristics.In this paper,enzymatic hydrolyzed lignin(EHL)was used as raw material,and a multiactive amphiphilic polymer was prepared by modifying it and introducing ellagic acid units.Based on the regulation of hydrophobic force,the ordered assembly of nanoparticles in selective solvents was realized,and a stable nanoparticle with multi-biological activity was obtained,and its application in biomedicine was discussed.(1)MEHL-g-PVP self-assembled nanoparticles.Copolymer maleylated lignin-g-polyvinylpyrrolidone(MEHL-g-PVP)was prepared by free-radical polymerization using enzymatically hydrolyzed lignin(EHL)and Nvinylpyrrolidone(NVP)as main raw materials.And then the copolymer was selfassembled to obtain pH-responsive nanoparticles with a diameter of about 40 nm.The effects of chemical modification,polymer concentration,water droplet acceleration,stirring speed,water content and dosage on the morphology,size and drug loading properties of nanoparticles were investigated.The results showed that the modification of polyvinylpyrrolidone(PVP)greatly improved the particle size of lignin nanoparticles from 318 nm to 91.43 nm,which was helpful for the transportation of nanoparticles in human body.The maximum drug loading of nanoparticles was 35.1%,and the encapsulation efficiency was 64.3%,The results of in vitro drug release experiments showed that MEHL-g-PVP had obvious pH-responsive ability.In simulated human intestinal environment and gastric juice,the 72h release of ibuprofen(IBU)was 63.8%and 11.1%,respectively.In vitro cytotoxicity test results showed that MEHL-g-PVP drugloaded nanoparticles were less toxic to normal cells but had a good inhibitory effect on colon cancer cells,with an inhibition rate of 56.9%.(2)EA-MEHL-g-PVP self-assembled nanoparticles.In order to further improve the tumor-targeting effect and drug loading capacity of nanoparticles,based on MEHL-g-PVP,ellagic acid molecular units was introduced by a simple esterification method,and a multi-active lignin-based nanoparticle(EA-MEHLg-PVP)was synthesized by solvent exchange method according to the principle of lignin macromolecular self-assembly.The structure of the polymer was verified by FTIR and 1H NMR.The results showed that the prepared nanoparticles were cage-like structures with compact morphology and the diameter was about 60 nm.The maximum drug loading of EA-MEHL-gPVP@PTX was 39.62%,and the encapsulation efficiency was 58.44%.The results of in vitro drug release experiment showed that EA-MEHL-g-PVP@PTX had good pH and reactive oxygen species response ability.The results of in vitro cytotoxicity test showed that EA-MEHL-g-PVP had high synergistic effect with PTX,significantly inhibited the activity of human colon cancer cells,and had good biocompatibility with mouse fibroblasts.At the same time,EA-MEHL-gPVP can target mitochondria in tumor cells,release in situ in mitochondria,destroy mitochondrial membrane potential,improve membrane permeability,promote the release of cytochrome C and Caspase 3.The results of in vivo experiments in mice prove that the nanoparticles have good tumor targeting ability in vivo,good safety in vivo,and have obvious tumor inhibition,and the tumor inhibition efficiency is as high as 73%.This ROS-responsive lignin-based nanoparticle enhances the chemodynamic therapy mechanism and effectively solves the problems of short lifetime and small action range of reactive oxygen species in tumor chemodynamic therapy.