Construction And Preliminary Evaluation Of Ptobiotics Cellulose-based Microcapsules

Probiotics have received widespread attention due to their probiotic effects such as improving intestinal microecological balance,regulating the inmmune system,and maintaining mucosal battiers.However,the surrounding environment such as processing,storage,and the human digestive environment have a great influence on the viability of probiotics.Microcapsule technology is an important method to protect probiotics.The use of microcapsule technology to deliver a sufficient amount of probiotics to the intestine to ensure that it exerts its physiological activity has become a research hotspot.In this study,cellulose-based microcapsules were prepared using cellulose fiber and cellulose nanofiber to study the effects of microcapsules on the loading,protection and controlled release behavior of probiotics.The main research contents and results are as follows:1.TEMPO media oxidation system can introduce carboxyl groups into cellulose fiber(CF)and it was used to prepare cellulose nanofiber(CNF).The content of carboxyls groups on the surface of cellulose nanofibers can be controlled by regulating the amount of NaClO used.When the amount of NaClO added was 7.5 mmol/g(cellulose),the carboxyl group content of cellulose nanofibers increased to 1.5 mmol/g.Analysis by means of FTIR,XRD,TGA,etc.fully demonstrated that the TEMPO media oxidation system effectively converts the C6 hydroxyl group on cellulose to carboxyl groups.2.Cellulose-based composite macrogels made by cellulose fiber/cellulose nanofiber(CCNM)were used as an intestine delivery vehicle for probiotics.The carboxyl groups in CNF acted as pore size and pH responsibility regulators in CCNMs to regulate the probiotics loading and controlled release property.The macrogel presented a porosity of 92.68%with a CNF content of 90%,and the corresponding released viable probiotics was up to 2.68×10~8 cfu/mL.The porous structure and high porosity benefited probiotics to infiltrate into the core of macrogels.In addition,the macrogels made with high contents of CNF showed sustainable release of probiotics and delivered enough viable cells to the desired region of intestine tracts.3.Cellulose nanofiber microcapsules(CNFM)are used as probiotic carriers and chitosan and sodium alginate were used as coatings to prepare core-shell microcapsules.It was found the probiotics were mainly distributed in the core of microcapsules.Furthermore,CNFM contracted in simulated gastric fluids(SGF)and gradually swelled after transferred to simulated intestinal fluid(SIF).While the CHI-ALG layer of CNFM-CHI-ALG contracted in SGF and gradually dissolved in SIF.And then the core of microcapsule was completely exposed to the SIF.Both CNFM-CHI-ALG and CNFM gradually released probiotics but the former had a more pro-protective effect on probiotics,and the probiotics release up to 1.2×10~6 cfu/mL.The design of the core-shell structure not only enables the sustained release of probiotics,but also ensures the delivery of a sufficient amount of bacteria to the intestine.