Construction And Application Of Gut-on-a-chip Integrated With Mechanical Stimulation And Dynamic Monitoring

In the process of drug development,more than 60%of drugs are administered orally,and are transported to other organs to achieve therapeutic purposes after digestion and absorption in the gastrointestinal.Therefore,it is necessary to explore the absorption and metabolism of oral drugs in the intestine,drug efficacy and safety evaluation.In the past,the research on drug screening was mainly based on animal models,but due to the species differences between animals and humans,more than 90%of the drug screening results were not suitable for humans,which intensified the development cycle and cost.Gut-on-a-chip provides an effective platform for researching intestinal drug development.Gut-on-a-chip can cultivate isolated intestinal cells,simulate the mechanical microenvironment in the human intestinal tract,and display the key characteristics of the human intestinal tract.At present,Gut-on-a-chip have made great progress in oral drug screening,personalized medicine and intestinal disease modeling.However,with the increase of biological complexity inside the chip,it is increasingly necessary to integrate sensors to dynamically monitor the physical and chemical parameters of the microenvironment of the chip.The integration of sensors in Gut-on-a-chip is of great significance for real-time acquisition of cell growth status and dynamic monitoring of cytokine secretion.In this paper,Gut-on-a-chip with the functions of culture fluid perfusion and mechanical stretching was firstly prepared.Gut epithelial cells(Caco-2)were dynamically cultured in Gut-on-a-chip.The cellular microenvironment was reestablished by applying fluid shear stress(0.02 dyne/cm~2)and cyclic mechanical strain(1%,0.15 Hz).Immunohistochemical analysis and microscopic observation verified that cultured cell monolayers formed intact tight junctions and were able to form villous-like protrusion structures that exhibited some of the characteristics of the human gut in a physiologically relevant manner.Secondly,we prepared a three-electrode electrochemical sensor by vacuum vapor deposition and shadow mask technology,integrated it into the Gut-on-a-chip and applied it in two aspects:1.Explore the absorption and transport mechanism of mercury ions in the intestinal tract.The surface of the electrochemical sensor is modified with a layer of gold nanoparticles to improve the sensitivity and stability of the sensor.The principle of redox reaction of mercury ions on the surface of the working electrode is used for detection,and the sensor has a good linear relationship between the concentration of mercury ions in the range of 1 n M-10μM.Different tensile strains were applied to the cells by controlling the air pressure changes in the vacuum chambers on both sides of Gut-on-a-chip.When the tensile strain increased from 1%to 5%,the uptake and transport of mercury ions by the cell monolayer increased by 23.59%,and the corresponding expression of Piezo1 and DMT1 proteins on the cell surface increased.2.Used to dynamically monitor the secretion of interleukin-6(IL-6).The surface of the electrochemical sensor was functionalized to achieve more sensitive and efficient capture of interleukin-6 secretion.The designed electrochemical sensor exhibited good linearity in the concentration range of IL-6 from 0.05 ng/ml to 100 ng/ml.Inflammation was constructed by applying 10μg/ml lipopolysaccharide to the cell monolayer with an intact barrier,and the secretion level of IL-6 was dynamically monitored within 48 h.