Construction And Characteristics Of Catechin Loading Rice Porous Starch/Chitosan Functional Microsphere And Its Exposure To Lead

In this paper,using rice raw starch（NRS）with fine particles,uniform palatability and low allergenicity as raw material,a functional microsphere particle carrier modified with chitosan（RPS/CS）was constructed on the basis of RPS skeleton for the fabrication of grade composite functional microsphere CT@RPS/CS.The loading characteristics,storage characteristics,sustained release characteristics and removal characteristics of heavy metal ions Pb²⁺were also systematically studied.The paper studied and evaluated the biological effects of CT@RPS/CS on lead exposure cells by Pb²⁺cell assay and transcriptomics analysis.The study found that the functional microspheres had good functional retention characteristics,sustained release delivery characteristics and synergistic effects of functional factor interactions during food processing,storage and metabolism.The research results provided important theoretical and technical support for the creation and quality improvement of functional foods.The main research methods and conclusions are as follows:（1）Rice porous starch was prepared by the complex enzymatic hydrolysis of NRS with amyloglucosidase andα-amylase and then modified by the chemical modification of CS to obtain RPS/CS.The characterization and analysis of FESEM,FTIR,XRD and nitrogen adsorption and desorption isotherms confirmed that RPS/CS had mesoporous structure and there was an intermolecular hydrogen bond between RPS and CS（O---H–O and O---H–N）.After modification by CS,the porous structure of PRS was not destroyed,and RPS/CS was positively charged,which was beneficial to the adsorption of CT.Taking the CT adsorption rate as an indicator,the optimal content of CS in the RPS/CS system was determined to be 25%.At the same time,it was found that although the increase of the specific surface area of the particle microspheres was beneficial to the adsorption of CT,the adsorption amount of CT mainly depended on the CS content of the surface of the RPS/CS microspheres.（2）Through the adsorption kinetics study of functional microspheres CT@RPS/CS loaded with catechin,it was found that the adsorption process of RPS/CS on CT could be effectively simulated by pseudo first-order and second-order models,confirming the mechanism of the adsorption of RPS/CS to CT was physical adsorption,chemical adsorption or strong surface complexation,and the adsorption capacity of RPS/CS to CT mainly depended on CS content.CT@RPS/CS had good sustained release characteristics with a moderate CT release rate and a good sustained release capacity in aqueous solution.In the in vitro simulated gastric juice test,after 8 h of release,the retention of CT in CT@RPS/CS functional microspheres was 34.60 mg/g,which maintained its biological activity and sustained release in the intestine.After release from simulated gastric juice,CT@NRS and CT@RPS could only maintain the controlled release capacity of CT for 30 min,and CT@CS release is very small,which could be ignored.Therefore,CT@NRS,CT@RPS and CT@CS were not suitable to be used as the carrier of CT alone,while CT@RPS/CS had good stable and sustainable release ability.（3）Compared with CT powders,CT@RPS/CS functional microspheres had good stability-maintaining properties for CT,which was beneficial to the maintenance of CT’s active components.Under the same storage conditions,the stability of CT@RPS/CS was significantly higher than that of CT,which could maintain the particle morphology better.The reason could be that the hydrophilic property of RPS/CS was weakened by the reaction of phenolic hydroxyl group of CT with CS.（4）Through the anti-oxidation analysis of·OH scavenging ability,reducing power and DPPH·clearing ability,the order of antioxidant capacity of NRS,RPS,RPS/RPS/CS and CS carriers after loading CT was:CT@NRS^CT@RPS>CT@RPS/CS>CT@CS.Its ability to resist oxidation was positively related to the amount of CT released in water.（5）CT has synergistic effect on Pb²⁺removal,and CT@RPS/CS significantly enhanced Pb²⁺removal ability relative to RPS/CS.Both pseudo first-order and second-order kinetic equations could describe the adsorption behavior of Pb²⁺by CT@RPS/CS,but the pseudo second-order kinetic equation was more effective,confirming the physical adsorption and chemisorption of Pb²⁺in the adsorption process of CT@RPS/CS.However,chemical adsorption(chemical complexation between Pb²⁺and CT)was dominant.（6）By establishing a Pb²⁺-exposed HT-29 cell model,it was found that Pb²⁺exposure could lead to a significant decrease in HT-29 cell activity.At the same time,it could induce the increase of ROS level in HT-29 cells,thus promoting the absorption of lead by the cell body.Using CT@RPS/CS to study the intervention,treatment and prevention of Pb²⁺-exposed HT-29 cells,it was found that CT@RPS/CS could effectively restore the activity of HT-29 cells after Pb²⁺exposure and reduced ROS produced by Pb²⁺induction.By cytokine detection,it was found that CT@RPS/CS could reduce the absorption of Pb²⁺by HT-29 cells after Pb²⁺exposure,resulting in the reduction of inflammatory cytokines such as IL-1β,IL-6,IL-8,TNF-αand IL-10.Therefore,it played a certain protective role,and reduced the toxicological effects of Pb²⁺in the host.（7）The Ctrl and Pb²⁺groups（6 samples）were sequenced and analyzed in the second generation by using the Illumina HiSeq platform.The sequencing data and the reference genome alignment analysis showed that the average ratio of the sample alignment to the genome was 83.11%.The total number of genes detected was 18,907,of which 16,751 were known genes and 2,368 were predicted.By comparing the expression genes of G-Pb group and Ctrl group,337 up-regulated genes and 408down-regulated genes were found,and GO and KEGG enrichment functions were analyzed.PPI interaction maps were used to obtain 10 important core genes.The mRNA profile of the differentially expressed genes after Pb²⁺exposure was established at the cellular level.Through the verification analysis of RT-qPCR,CT@RPS/CS was found to play a role in the core genes related to Pb²⁺exposed cells,and exerted certain intervention,treatment and prevention effects on HT-29 cells.