Construction Of Polysaccharide Nano-Selenium Carrier And Study On Its Structure-Activity Mechanism

Inflammation is a physiological and pathological reaction that occurs when the body is stimulated by proinflammatory factors.Moderate inflammation plays an important role in the body as a beneficial defense response,but excessive inflammation can cause tissue damage and functional disorders.G.lucidum polysaccharide(PS)is a rich dietary fiber raw material with the characteristics of natural low toxicity.However,since PS is obtained by alkaline extraction,its water insolubility affects its related properties.As a highly bioactive,low-toxic selenium product,SeNPs has attracted much attention in anti-tumor and anti-inflammatory effects.However,due to the high surface energy of the SeNPs,it is difficult to prepare a stable solution.Therefore,in this thesis,a stable,size-differentiated SPS-SeNPs was prepared by using the sulfated modified PS as a template.An in vitro inflammatory model of LPS-stimulated RAW264.7 cells was established to evaluate the anti-inflammatory effects of different sizes of SPS-SeNPs,and to explore their activity-activity relationship.The main findings are as follows:(1)Sulfur trioxide trimethylamine(STMA)was used as esterification reagent to modify the sulfation of PS.By changing the different reaction conditions,10 SPS with different degrees of substitution were prepared.The maximum degree of substitution was0.28,the minimum is 0.02.Infrared and nuclear magnetic results show that the sulfate group is mainly connected to the PS by a substitution reaction.In addition,the solubility and stability tests of 10 SPSs showed that the solubility and stability of SPS increased to some extent with the increase of STMA dosage.(2)SPS-1,SPS-3 and SPS-7 with substitution degrees of 0.02,0.06,0.25 were used as templates,and three different sizes of 123.04±20.36 nm,69.65±16.79 nm and54.35±9.13 nm were prepared by adjusting different reaction conditions.The selenium content of three SPS-SeNPs was 0.172%,0.274%,and 0.305%,respectively.TEM and LLS-SEC showed that SeNPs showed uniform spherical shape and SPS-SeNPs increased in molecular weight compared with SPS due to adsorption.(3)Establish an in vitro inflammation model of LPS-stimulated RAW264.7 cells.MTT assay determined 1.25,2.5,5,and 10 μg/m L as safe concentrations for subsequent activity studies.The results of the Griess method for detecting NO concentration showed that compared with the LPS group,the three SPS-SeNPs treated had a certain inhibitory effect on NO production.The inhibitory effect of SPS-SeNPs-S was the most significant.This indicates that SPS-SeNPs mediated anti-inflammatory effects have a certain size effect.The results of q RT-PCR showed that different sizes of SPS-SeNPs inhibited the m RNA expression of Tumor necrosis factor-α(TNF-α)、Interleukin-1β(IL-1β)and Inducible nitric oxide synthase(i NOS)at 5 μg/m L.This indicates that SPS-SeNPs-mediated inflammation inhibition was involved in the modulation of TNF-α,IL-1β and i NOS gene expression at the transcriptional level.