Construction And Efficacy Evaluation Of Pectin-based Nano-drug Carriers

Pectin is a kind of complex plant polysaccharide and consists of galacturonic acid skeleton and neutral sugar side chain,which has non-toxic,biodegradable and high bioavailability.In addition,the biological activity of pectin is to regulate immune response,inhibit tumor growth and metastasis,induce biological activity,induce apoptosis.Pectin has a great potential for drug delivery as a drug carrier.At present,there are few reports on the drug delivery system of pectin-based,and low drug loading rate,short half-time,lack of targeting limit the application of pectin-based drug carriers.In order to improve the drug loading properties of pectin,effective controlled-release,sustained release effective and active targeting need to be considered.In this paper,a series of pectin prodrugs and pectin-based nanoparticles were designed and prepared,and the drug efficacy were evaluated.The main work of the thesis is as follows:1.The water-soluble prodrug was prepared by pectin-conjugated dihydroartemisinin(DHA),and the hydrophobic drug 10-hydroxycamptothecin(HCPT)was introduced to prepare nanoparticles by self-assembly.The physicochemical properties and drug efficacy of nanoparticles were evaluated.Pectin and DHA are linked via an ester bond to form pectin-dihydroartemisinin prodrug.The preparation of pectin-dihydroartemisinin/10-hydroxycamptothecin nanoparticles(PDC-H NPs)is to self-assembe with hydrophobic drug HCPT by using the hydrophobic end(DHA)and hydrophilic end(pectin)of the prodrug,which can achieve the purpose of combination therapy and co-delivered.The results indicated that the particle size of PDC-H NPs was about 70 nm,drug-loaded efficiency of DHA was 20.33 wt%,and encapsulation efficiency of HCPT was 14.11 wt%.PDC-H NPs exhibited a higher cytotoxicity,the blood retention time of PDC-H NPs was 4.8-fold longer than DHA and was 6.8-fold longer than HCPT.In addition,4T1 tumor-bearing mice also showed a higher survival rate than free DHA and free HCPT.2.Preparation and efficacy evaluation of drug-loaded nanoparticles based on pectin-(eight-arm polyethylene glycol)-dihydroartemisinin conjugates(Pectin-8arm-PEG-DHA).Eight-arm polyethylene glycol was chemically linked with dihydroartemisinin,and then coupled with pectin to form pectin-(eight-arm polyethylene glycol)-dihydroartemisinin.The hydrophobic drug HCPT was encapsulated to prepare pectin-(eight-arm polyethylene glycol)nanoparticles(PPDH NPs)by self-assemble.Results showed that the prepared PPDH NPs had the advantage of stabilizing particle size,improving water solubility and achieving drug controlled release.The obtained nanoparticles possessed appropriate size(84 nm),drug-loaded efficiency(9.13 wt%DHA),encapsulation efficiency(12.03 wt%HCPT),and good stability and were pH-dependent.The PPDH NPs exhibited a higher cytotoxicity(119.40-fold 4T1,100.57-fold MCF-7),respectively,longer blood retention time of free drug(8.0-fold DHA,7.4-fold HCPT).4T1 tumor-bearing mice treated with the nanoparticles also showed a considerable survival advantage(90.6%).3.Preparation and efficacy evaluation of drug-loaded nanoparticles based on pectin-(eight-arm polyethylene glycol)-ursolic acid conjugates(Pectin-8arm-PEG-UA).Eight-arm polyethylene glycol was coupled with ursolic acid(UA)to prepare eight-arm polyethylene glycol-ursolic acid(8arm-PEG-UA)conjugates,and chemically linked with pectin to form pectin-eight-arm polyethylene glycol-ursolic acid conjugates,and then self-assembled with HCPT to prepare a stable and uniform pectin-(eight-arm polyethylene glycol)-ursolic acid/10-hydroxycamptothecin nanoparticles(Pec-8PUH NPs).As a control,pectin-conjugated single-arm polyethylene glycol nanoparticles were prepared pectin-polyethylene glycol-ursolic acid/10-hydroxycamptothecin nanoparticles(Pec-PUH NPs).The obtained Pec-8PUH NPs possessed appropriate size(91 nm),high drug-loaded efficiency(9.22 wt%UA)and encapsulation efficiency(16.5 1 wt%HCPT)through the regulation of eight-arm polyethylene glycol.In addition,Pec-8PUH NPs could enhance cell cytotoxicity,shorten blood retention time and enhanced EPR effects.4.Preparation and efficacy evaluation of drug-loaded nanoparticles based on dual-targeted folic acid-pectin-(eight-arm polyethylene glycol)-dihydroartemisinin conjugates(Pectin-8arm-PEG-DHA).The galactose residue of pectin can selectively recognize the asialoglycoprotein receptor(ASGPR)on the surface of liver cancer,which has the advantage of preparing active targeted pectin-based nanoparticles.Pectin is coupled with folic acid,and connected to the eight-arm polyethylene glycol-dihydroartemisinin to prepare folic acid-pectin-(eight-arm polyethylene glycol)-dihydroartemisinin(FPPD)prodrugs.The dual-targeted,double-loaded folic acid-pectin-(eight-arm polyethylene glycol)-dihydroartemisinin/10-hydroxycamptothecin nanoparticles(FPPDH NPs)are prepared to encapsulate HCPT.The results showed that FPPDH NPs had a high drug loading rate(7.04 wt%DHA),embedding rate(20.57 wt%HCPT)and stable particle size(98 nm).The cytotoxicity of nanoparticles was 204.5-fold(H22)and 178.4-fold(HepG2)to the free DHA,respectively.Dual-targeted FPPDH NPs can actively target tumor tissues through blood circulation,improving the ability of drug capture capacity and tumor surface enrichment.5.Preparation and efficacy evaluation of drug-loaded nanoparticles based on dual-targeted folic acid-pectin-(eight-arm polyethylene glycol)-ursolic acid conjugates(Pectin-8arm-PEG-UA).The co-carrier was prepared by coupling pectin with eight-arm polyethylene glycol.Folic acid-pectin-(eight-arm polyethylene glycol)-ursolic acid(FPPU)conjugates were prepared by inducing targeted folic acid and anticancer drug UA,and then self-assembled with hydrophobic drug HCPT to prepare folic acid-pectin-(eight-arm polyethylene glycol)-ursolic acid/10-hydroxycamptothecin nanoparticles(FPPUH NPs).The obtained FPPUH NPs had a high drug loading(7.27 wt%UA),embedding rate(19.84 wt%HCPT),and stable,uniform nanoparticle size(105.72nm).The enhanced cytotoxicity of FPPUH NPs was 250.8-fold(H22)and 226.8-fold(HepG2)to the free UA,respectively,and the cytotoxicity of FPPUH NPs was 11.0-fold and 9.2-fold to the free HCPT.The continuous circulation time of nanoparticles in the blood was as high as 80h,and the survival rate as high as 76.11%after 30 days’treatment.In addition,the synergistic inhibition of drugs to tumors is significant.In summary,a series of well-defined pectin-based nanoparticles were prepared by using the drug models(DHA,UA and HCPT),which showed good efficacy in vivo and in vitro evaluation.Actually,this strategy provided a facile method to prepare well-defined drug carriers with various drugs and a versatile method for the design of nanostructures.This article provides more ideas for the design and application of pectin-based nano drug delivery systems.