Preparation Of Porous Starch-alginate Microbeads And Entrapment Of Lutein By Pulsed Electric Field Assisted Enzymatic Hydrolysis

In order to overcome the limitations of?BCS?Class II drugs with low water solubility and poor stability in oral drug delivery systems,this thesis proposes a novel oral drug delivery system that combinedthe use of porous starch carrier and alginate coating to improve the drug bioavailability in the body.Using waxy corn starch as raw material,the combined use of pulsed electric field?PEF?treatment and enzymolysis was used to prepare porous starch,and the effect of PEF on the hydrolysis rate and oil absorption rate of starch was evaluated.The results showed that after PEF modification,the duration of hydrolysis required for the starch hydrolysis rate to reach24.28%,was shortened by half;under the same conditions?amount of enzyme and duration of hydrolysis?,following PEF modification,the starch hydrolysis rate was 23.11%,which was significantly higher than that of the original starch.Furthermore,PEF treatment was found to be able to shorten the duration of enzymolysis and reduce the amount of enzyme added to the enzymolysis process,thereby saving significant industrial costs and time.The morphological and structural characterization of PEFmodified porous starch was evaluated.Scanning electron microscopy?SEM?results demonstrated that PEF modification can give rise to a grooved-like structure on the surface of starch granule;confocal laser electron microscopy?CLSM?observation showed that PEF modified starch particles were distributed with more channels;particle size analysis and pore volume pore size analysis showed that PEF treatment increased the pore volume,pore size,specific surface area and particle size of the original starch;gel permeation chromatography?GPC?showed that PEF treatment has successfully broken down the glycosidic bond of the amylopectin molecules,causing the branch amylose to precipitate out;results of Thermodynamic property measurements showed that the enthalpy value(?H_gel)of PEF modified starch was lower than that of original starch,indicating that PEF modification has disrupted the multi-scale structure of starch granules and destroyed some of the dense crystalline regions within the starch granules,thus increasing the permeability of raw starch granules,therebyaugmenting the efficiency of enzymatic hydrolysis.Using lutein as a model drug and the porous starch encapsulated?L/PS?with lutein oil as a control,gel microspheres?L/PS/1%AG and L/PS/2%AG?with sodium alginate concentration of 1%and 2%?w/v?were prepared to explore the effect of sodium alginate concentration on encapsulation efficiency and drug release profile.The encapsulation efficiency of lutein was observed:L/PS?95.85%?>L/PS/2%AG?81.55%?>L/PS/1%AG?71.25%?.The low encapsulation efficiency of samples with alginate may be attributed to the loss of lutein during the gelation of sodium alginate,and the greater gel crosslink density when higher concentration of sodium alginate was used.In vitrodrug release studies showed that the release of lutein in simulated gastric fluid?SGF,p H=1.2?was faster than that of simulated intestinal fluid?SIF,p H=6.8?,and the sodium alginate gel microspheres remained intact in gastric juice,hindering the release of lutein.However,in its swollen state in SIF,the rate of lutein release was increased.Moreover,the rate of lutein release from L/PS/1%AG was faster than L/PS/2%AG,because higher sodium alginate concentration will form microspheres with higher density and mechanical strength,thus forming a stronger fixed matrix,which in turn affected the dissolution rate of lutein.In conclusion,the experimental results have successfully validated the functional characteristics of the novel drug delivery system for the improvement ofthe delivery of oral drugs with low solubility and stability.