Synthesis And Biological Activity Of Nano-Selenium Based On Polysaccharide Micro/Nano Carrier

As a new type of selenium supplement,nano-selenium has higher safety and biological activity than traditional selenium preparation,and has become a research hotspot.However,nano-selenium aggregates easily and is easily converted into black or gray elemental selenium with no biological activity,which limits its antioxidant and anti-tumor activities.Aiming at the problems,this study using starch as raw materials,micro/nano carrier to build two kinds of polysaccharides(i.e.,starch microgels and glucan nanoparticles),study its in the process of nanometer selenium cooperative effect on the stability of the nanometer selenium,and further from the perspective of "small molecules-macromolecular interactions,study the effects of polyphenols in polysaccharide-nanometer selenium system stability,the relationship between and antioxidant and the rule of variation of antitumor biological activity,the concrete research content is as follows:(1)Preparation of starch microgel(SM)by cross-linking with sodium trimetaphosphate,and polysaccharide in the form of gel as the carrier,using the method of in situ reduction synthesis of selenium nanoparticles,build starch microgelsnanometer selenium system(SM-SeNPs),at the same time,the use of molecular interaction,the nanometer selenium system introduced in table gallic acid ester gallic catechins(EGCG),and micro gel-EGCG-nanometer selenium ternary system(SMEGCG-SeNPs),selenium loads of 183.2±8.4 ?g/mL,the average particle size of 82.1±3.3 nm.The starch microgel was closely bound to nano-selenium by Se-O bond,which played a role in stabilizing nano-selenium during the synthesis process,and enhanced the stability of nano-selenium at pH(e.g.,1.4-9.4)and temperature(e.g.,460?).In addition,the introduced EGCG could also inhibit the aggregation of polysaccharide molecules while disperses nano-selenium.Therefore,SM-EGCGSENPs were more stable than SM-SENPs,and the storage time was increased to 25 d.(2)Glucose nanoparticles were prepared by enzymatic hydrolysis,and polysaccharides in the form of nanoparticles were used as the carrier,combined with rosmarinic acid(RA)as the dispersant,Glucan-RA-SeNPs system was constructed by"one-pot method".The selenium content was 177.5±5.6 ?g/mL,and the average particle length was 69.4±2.7 nm.The glucose nanoparticles and RA could also disperse nano-selenium,and RA could also inhibit the accumulation of glucose molecules.In addition,due to the low sensitivity of RA to pH and temperature,Glucan-RA-SeNPs were more stable at higher pH and temperature than Glucan-SeNPs.(3)The biological activities of nano-selenium system constructed by polysaccharides were investigated by in vitro antioxidant test and in vitro anti-tumor activity study.In the starch microgel nano selenium system,nano selenium showed good free radical scavenging ability.Due to the synergistic antioxidant effect of EGCG,the free radical scavenging ability of SM-EGCG-SENPs was significantly improved.At the same time,SM-EGCG-SENPs can induce the production of intracellular reactive oxygen species(ROA)and promote the activation of caspase-3 and caspase-9 to induce the apoptosis of HepG2 cells.In the Glucan nano selenium system,the introduction of RA significantly improved the biological activity of Glucan-RA-SeNPs,and the results showed that compared with the Glucan-SeNPs table,it had more excellent free radical scavenging ability.Moreover,Glucan-RA-SeNPs more prominently promote the generation of ROS and the activation of Caspase-3 and Caspase-9 to induce apoptosis and inhibit the proliferation of HepG2 cells.