Oral Delivery Of Superoxide Dismutase By Lipid Nanoparticles For The Treatment Of Ulcerative Colitis

In recent years,protein drugs have attracted extensive attention in the field of drug research because of their advantages of good specificity,high biological activity and significant therapeutic effect.However,due to factors such as large molecular weight,complex structure,easy degradation and deactivation,and difficulty to passively diffuse through intestinal epithelial cells,protein drugs are difficult to absorb and need to be administered at a higher frequency,which not only reduces the quality of life of patients but also causes various side effects.Oral administration is a controlled method of administration,which is convenient and has significant advantages.Therefore,to protect the biological activity of protein drugs,it is necessary to develop a safe and effective oral delivery system for the application of protein drugs.Lipid polymer hybrid nanoparticles(LPNs)are a new nano-drug delivery system that combines the advantages of liposomes and polymer nanoparticles.LPNs is the core to improve the drug encapsulation rate,control the release of drugs,and provide a certain support for the outer lipid layer,increase its stability;The outer lipid layer makes lipid nanoparticles similar to cell membranes and has good biocompatibility,so lipid nanoparticles are a promising nanodelivery system.In this paper,PCADK and PLGA were used to form the inner carrier of lipid nanoparticles,so that the core of lipid nanoparticles was acid-sensitive,and lecithin was added to protect the outer layer of the nanoparticles.Due to the multi-layer barrier of oral absorption process,the nanoparticles were modified by Sta-R8 and DSPE-PEG to improve the absorption efficiency of nanoparticles.The effect of lipid nanoparticles was studied preliminarily.The detailed content includes the following parts:1.Establishment of SOD analysis method in vitroIn this chapter,the content of SOD was detected by Micro BCA kit,and an analysis method for SOD detection in vitro was established.The standard curve of SOD(0.0～60.0μg/m L)has a good correlation,and its linear regression equation is y=0.0003277x+0.001838,R~2=0.9995.Through the detection of 2.5μg/m L,10.0μg/m L,40.0μg/m L SOD solution,the accuracy of the method is in the range of 98%to 102%,and the RSD of intra-day and inter-day precision is less than 2%,indicating that the Micro BCA kit method for detecting SOD content has good accuracy and precision,and this method meets the requirements.2.Preparation of lipid nanoparticles co-modified with Sta-R8 and PEGIn this chapter,PCADK was synthesized by ketal reaction of 1,4-cyclohexanedimethanol(CDM),1,5-pentanediol(1,5-PED)and2,2-dimethoxypropane(DMP).The results showed that the five characteristic absorption peaks were 3.19-3.20 ppm,1.84 ppm,1.45 ppm,0.94 ppm and 1.32 ppm.The result is consistent is consistent with the structure of PCADK.FTIR results show that the stretching vibration peak of the compound is consistent with the structure of PCADK.Then,the crystallinity of polyketal material was analyzed by X-ray powder diffraction experiment.And the result demonstrates the PCADK part existed in the form of a crystal.Then,lipid nanoparticles were prepared by PCADK,PLGA and Egg PC,and the lipid nanoparticles were co-modified by Sta-R8 and DSPE-PEG.The formulation of lipid nanoparticles was optimized by studying particle size,polydispersity index(PDI),potential and drug loading.The optimized nanoparticles had a particle size of 136.0±1.17 nm,a PDI of 0.182±0.028,and potential of 2.38±0.47 m V.3.Evaluation of lipid nanoparticles co-modified with Sta-R8 and PEGIn this chapter,the physicochemical characterization,cell uptake,cytotoxicity and pharmacodynamics of ulcerative colitis in mice were studied on the lipid nanoparticles prepared by the optimal formulation.In the study of in vitro stability and release of nanoparticles,lipid nanoparticles showed good stability and protective effects.In cell uptake and cytotoxicity experiments,nanoparticle carriers have no toxic effects on cells and can improve drug uptake efficiency.In the experiment of DSS-induced ulcerative colitis mice,the efficacy of LPNs was evaluated using body weight,DAI index,pathological test results and blood inflammation index as indexes.Compared with PPNPs group,the inflammatory factors in Sta-R8-PEG-PPNPs group were significantly decreased(P<0.05).These results indicated that Sta-R8-PEG-PPNPs could effectively treat ulcerative colitis.In summary,the lipid nanoparticles co-modified by Sta-R8 and PEG are a promising drug delivery system for SOD oral delivery.