Preparation And Characterization Of Selenium Nanoparticles Modified By Folic Acid-chitosan Conjugates

Selenium(Se)is an essential trace element for human,it exerts many biological functions,such as scavenging free radical,anticancer,antioxidation and so on.In particular,selenium nanoparticles(SeNPs)have garnered a great deal of attention due to its better bioavailability,low toxicity and the good synergistic anticancer effect with anticancer drugs.Nevertheless,there are some drawbacks of SeNPs,such as poor stability in aqueous solutions and low selectivity toward cancer cells,thus limit its applications in the areas of anticancer.In order to resolve these above problems,this study carried out the following works:(1)Folic acid(FA)was used as the cancer-targeted ligands to modify the chain of chitosan(CS),and the coupling ratio between folic acid and chitosan was improved by optimized the reaction conditions.The structure of FA-CS conjugates was confirmed by Thin layer chromatography(TLC),Fourier transform spectroscopy(FT-IR)and Nuclear magnetic resonance(~1H-NMR).In order to improve the coupling ratio between folic acid and chitosan,the single factor investigation and orthogonal experiment were used to optimize the reaction conditions.The results showed that CS was successfully modified by FA,and the best reaction conditions are as follows:the reaction temperature was 50?,the reaction time was 24 hours and the feed ratio of FA:CS was 2:1(w/w),according to the above conditions to react,the average couling ratio of the products was17.58%.(2)The selenium nanoparticles modified by FA-CS conjugates(FA-CS-SeNPs)were prepared,and the mean particle size,size distribution,Zeta potential,morphology and the physical stability of FA-CS-SeNPs were evaluated.FA-CS-SeNPs were prepared through reduction of sodium selenite with ascorbic acid in the presence of FA-CS conjugates.The properties in terms of particle size,size distribution,Zeta potential,and morphology were evaluated by dynamic light scattering(DLS)and transmission electron microscopy(TEM),respectively.The physical stability of FA-CS-SeNPs were studied by resonance Rayleigh scattering(RRS)and DLS.The TEM results showed that SeNPs was successfully coated by FA-CS,and FA-CS-SeNPs were spherical in shape with the uniform particle size around 50nm.The DLS results showed that the Zeta potential of FA-CS-SeNPs was+52.70mV,the mean particles size was 69.48±1.63nm and the PDI was 0.16 which indicated that the size distrution was uniform.In addition,the physical stability of FA-CS-SeNPs was excellent,and FA-CS could avoid the agglomeration of SeNPs effectively.(3)The targeting ability,anti-cancer effect of FA-CS-SeNPs and the biocompatibility of FA-CS conjugates were evaluated.The cytotoxicity of FA-CS-SeNPs,CS-SeNPs and FA-CS on A549 cells and HeLa cells were examined by MTT assay to evaluate the cancer-targeted ability,anti-cancer effect of FA-CS-SeNPs and the biocompatibility of FA-CS conjugates.The results showed that the biocompatibility of FA-CS was excellent,and the conjugation of FA-CS enhanced the anticancer efficacy of SeNPs toward HeLa cells due to the specific binding between FA and folate receptors.(4)The cancer-targeted drug delivery system co-delivering fluorescein-loaded liposomes and SeNPs was designed and evaluated.Fluorescein was used as the model drug to prepare liposomes,and then the prepared liposomes were used to prepare FA-CS-SeNPs-Lips.The size distrution of liposomes,the Zeta potential of liposomes and FA-CS-SeNPs-Lips were evaluated by DLS.The morphology of liposomes and FA-CS-SeNPs-Lips were observed by TEM.The vitro release of fluorescein from liposomes and FA-CS-SeNPs-Lips were studied by dialysis method.The cell selectivity and the cell uptake of fluorescein were examined by fluorescence microscope and fluorescence spectrophotometer.The results showed that FA-CS-SeNPs-Lips with higher Zeta potential(+42.63mV)which indicated the high stability.And FA-CS-SeNPs-Lips could significantly delay the release of fluorescein compared with liposomes.In addition,FA-CS-SeNPs-Lips enhanced the cellular uptake ability of fluorescein on HeLa cells due to the specific binding between FA and folate receptors.