| In this paper,pineapple pulp cellulose was extracted from pineapple pulp residue and used to prepare hydrogels linked in ionic liquid of 1-butyl-3-methylimidazole chloride(Bmim Cl).The hydrogels were used to embed probiotics.The structures of the prepared hydrogels were charactrized and their performance researches were studied.The results provide a reasonable approach and theoretical basis for the high-value utilization of pineapple waste and the delivery system of probiotics.The main results of this research are concluded as follows:(1)Pineapple pulp cellulose was extracted from Pineapple pulp residue through hot water treatment,bleaching treatment and alkali treatment equently,and the structures were characterized.The effects of alkali dosage,alkali treatment temperature and alkali treatment time on cellulose yield were investigated through single-factor experiments and response surface experiments.The characterized results showed the typical characteristic absorption peaks of lignin and hemicellulose almost completely disappeared in pineapple pulp cellulose,and more crystalline parts were found exposed,and the surface roughness increased and the bundle structure was destroyed after the pineapple pulp residue was bleached and alkali treated.The response surface experiment showed that the pineapple pulp cellulose yield was the highest at 48.67% at 10.10% of alkali concentration and 50.05?,and for 4.98 hours for alkali treatment time.(2)The extracted pineapple pulp cellulose was used to prepare traditional hydrogel by dissolving in Bmim Cl and p H-sensitive hydrogel by modifing with acrylic acid.The structures were characterized and the properties were determined.The prepared hydrogels were used as a carrier to adsorb probiotics,and the sustained release properties in the intestinal and gastric simulated p H environment were studied.The characteristic absorption peak of the carbonyl group was found for the p H-sensitive hydrogel,indicating that acrylic acid was successfully grafted onto the cellulose chain;pineapple pulp cellulose changed from type I crystal structure to type II during the preparation of hydrogel;the original bundle-like structure disappeared and a dense porous structure was observed after cellulose was prepared into a hydrogel.Compared with pineapple pulp cellulose hydrogel,the p H-sensitive hydrogel exhibited obvious p H sensitivity,and its cumulative release amount under the intestinal simulated p H environment was much higher than that under the gastric simulated p H environment.The cumulative release amount and the release rate reached 58.01 mg/g and 87.02% respectively.(3)Cholesterol and soybean phosphate were prepared into the probiotic liposomes(Pro-lips)through film hydration method.The optimal raw material ratio and preparation process were reached through single factor experiments and orthogonal experiments using the encapsulation rate of the probiotics as evaluation index.The properties were also characterized.A hydrogel-liposome composite drug-loading system was constructed with pineapple pulp cellulose hydrogels adsorbing Pro-lips.The release behavior of this system under the intestinal and gastric simulated p H environment was studied.The results showed that the optimal parameters for preparation of liposomes was as follow: probiotic: lecithin: cholesterol mass ratio was 1:12:2,the drug concentration was 1.5 mg/m L,andhydration at 60°C for 2 h.The liposomes exhibited a spherical particle morphology,evenly distribution with no adhesion.The average particle size of the prepared liposomes was 147.52±9.86 nm(n=3),and the zeta potential was-15.33±1.07 m V(n=3).The encapsulation efficiency reached about 62.53%.Compared with bacteria-bearing hydrogels,the hydrogel-liposome composite drug delivery system had a better sustained-release effect.The hydrogel PPCH-AA loaded with probiotic liposomes showed significant p H sensitivity.The cumulative release under the intestinal simulated p H environment was 49.98 mg/g,the total cumulative release rate was 74.97%. |
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