Preparation And Biological Function Of Alginate Oligosaccharide Nanoliposomes

Alginate oligosaccharide(AOS)is an oligomer,which is linear polymer of polysaccharides with gel-forming properties composed of alternating blocks of β-(1-4)-D-mannosyluronic acid(M),α-(1-4)-Lglucosyluronic acid(G).Alginate oligosaccharide is regarded as a non-toxic,nonimmunogenic and biodegradable oligosaccharide and possesses additional biological characteristics such as antitumor,antimicrobial activities and antioxidant properties.To expore the functions of AOS,it is necessary that the bioavailability would be improved in the view of its expensive cost.Liposomes is a kind of vesicle with membrane phospholipid bilayer molecules,which can effectively transport active substance through cell membrane.In this study,our objectives aimed at finding out the best preparation conditions of AOS nanoliposomes through the response surface design test,and investigating its effects for water-holding capacity of the shrimps.Furthermore,antimicrobial activities,antioxidative activities,and inhibitory effect on the growth of tumor cells about AOS nanoliposomes were studied in this paper.Specific results are as follows:1.AOS nanoliposomes were prepared by reverse evaporation method.The optimal preparation conditions for AOS nanoliposomes by single-factor experiments and response surface methodology were as follows: phosphatidylcholine-to-cholesterol ratio of 5.12,AOS concentration of 8.44 mg/mL,Tween 80 concentration of 1.11%,and organic phase to aqueous phase ratio of 5.25.Under the above conditions,the prepared AOS nanoliposomes have the highest encapsulation efficiency of 65.84%,and a small particle size of 323 nm.2.Leak rate was used as the index to evaluate stability,and it was examined how pH value,temperature,ultrasonic time,storage time,simulated gastrointestinal fluid environment had an effect on the stability of AOS nanoliposomes.The results showed that acidic environment and high temperatures could affect the stability of nanoliposomes through damaging the membrane structure.The increase of ultrasonic time would lead to the release of the leak rate of liposome.After liposomes were stored at the 4℃ condition for two weeks,the leak rate was less than 3%.The liposome could protect AOS damage against the simulated gastrointestinal fluid environment.3.In this experiment,water holding capacity of shelled shrimps was examined by single-factor experiments and orthogonal experimental design.The optimal formula of water retaining agent was 2:1:1:2:2 of AOS oligosaccharide:sodium chloride:sodium bicarbonate:citric acid three sodium:sorbitol.Shelled shrimp samples could get the macerate increase rate to 11.76%,defrost increase rate for 8.18%,and cooking loss rate for 7.23% with the treatment of above water retaining agent.The weights of shelled shrimp treated with distilled water or compound phosphate solution or AOS composite aquasorb were increased by 5.37%,9.81%,or 10.19%,but significantly increased by 12.02% after treated with AOS liposome composite aquasorb(P<0.05).The thawing loss of shelled shrimp treated with AOS liposome composite aquasorb was-8.36%,which was significantly lower than that of distilled water or compound phosphate solution treatment(6.15% or-3.70%)(P<0.05).The cooking loss of shelled shrimp,after treated with AOS liposome composite aquasorb,was 7.55%,which was significantly lower than that of distilled water or compound phosphate solution treatment(30.33% or 12.63%)(P<0.05).4.Oxford cup antibacterial experim ents demonstrated that AOS nanoliposomes have better inhibitory effect on several common pathogenic bacteria(Salmonella,Escherichia coli,Bacillus cereus,Shigella and Listeria monocytogenes).Through the study of antioxidant activities in vitro,AOS nanoliposomes showed significantly better effects of DPPH radical scavenging activity and the hydroxyl radical scavenging activity than AOS(P<0.01);and the DPPH radical scavenging activity and the hydroxyl radical scavenging activity of AOS nanoliposomes were 45.78% and 55.86% at a concentration of 3000 μg/m L,respectively.In order to prove if AOS nanoliposomes could have inhitory effect on cancer cells,MTT assay,LDH assay kit,CCK and AO/EB were carried out in the experiment.MTT results showed that the cell activity of AOS nanoliposomes was 53.23% at a concentration of 0.5 mg/ml,and the effects is better than that of AOS(P < 0.01).LDH assay results showed that the LDH leakage of AOS nanoliposomes was 66.32% at a concentration of 0.5 mg/ml,which had more significantly higer than that of AOS(P < 0.01).CCK results showed that the cell activity of AOS nanoliposomes was 52.04% at a concentration of 0.5 mg/ml,which had more significantly higher than that of AOS(P < 0.01).The above results were also supported by AO/PI.