Microfluidic Chip Based On Bionic Principle Of Reticular Venation For Cell Culture And Drug Analysis

Cells are the basic units of the human body.Cell research is not only helpful to understand the causes and development of the disease,but also of great significance to the research and development of therapeutic drugs.Cell research is mainly carried out in vitro,which needs to provide a dynamic and stable liquid microenvironment similar to in vivo.The vascular system of fluid supply for cells in vivo can be constructed approximately on microfluidic chip,which makes it possible to simulate and control the cell microenvironment in vitro.In this paper,a design method of microfluidic unit based on the fluid transport redundancy mechanism of reticular vein is proposed.The characteristics of fluid flow in the bionic microfluidic chip are analyzed.Microfluidic chips with uniform and stable flow field,regional concentration distribution are fabricated,which is applied to cell culture and tumor drug action analysis.The main research content is as follows:(1)Research on redundant mechanisms of leaf reticular vein.Based on the bionic principle of reticular venation and the extraction of vein features,the structure,classification and functional characteristics of dicotyledonous plant veins are analyzed.The effects of hierarchical bifurcation structures,areoles and pits on liquid redundant transportation are studied.The conditions for maximizing the transport efficiency of the bifurcation channels of the veins are studied based on the Hagen-Poiseuille equation.The Capability of polygonal areole structure for resisting external flow disturbances are are studied based on the closure theory and the flow entropy equation.The effects of pits on uniformity of flow field are studied by numerical simulations.The results provide theoretical basises for the modeling of cell culture microfluidic unit.(2)Design of the biomimetic microfluidic chips for cell culture,generating regional drug concentration and targeted drug screening.The bionic structure was extracted according to the bionic function of the reticular veins.The cell culture microfluidic unit,regional drug concentration generation unit and serial-parallel coupled cell co-culture unit are designed.The finite element simulation method is used to analyze the flow field distribution characteristics in each unit.On the premise that the flow field of the cell analysis unit is not affected,2D culture microfluidic chips with multilayer structures are designed,and the fluid flow characteristics in each bionic microfluidic chip are analyzed using particle tracking technology.The parallel-coupled cell co-culture unit is integrated with the Christmas tree-shaped concentration gradient generator.By changing the structure size of the Christmas tree-shaped concentration gradient generator,effective and sufficient mixing of molecular-level to micron-level particle suspensions is achieved.A microfluidic chip for 3D dynamic cell culture is also designed based on the bionic redundant mechanisms.(3)Fabrication of 2D/3D cell culture microfluidic chip and develop a micro fluidic chip cell dynamic culture device.The soft etching technology is used to produce PDMS microfluidic chip substrates and coverslips.Alignment bonding of multi-layer bionic 2D culture microfluidic chips is performed using visual alignment equipment.3D culture microfluidic chip with "sandwich" structure are fabricated.The upper chip layer is fabricated by two photolithographic techniques to produce elastic microstructures with concave and convex features.This structure fixes the scaffold embedded in the bottom chip with an interference fit and prevents the bracket from being scoured and deformed.The middle scaffold layer is fabricatied using a thermal field assisted electric jet 3D printing technology.A microfluidic chip dynamic cell culture device is developed by using a split design.The wet etching is used to prepare an ITO heater,and the thermodynamic simulation of the temperature fields are analyzed.Using PMMA as the box material,the related hardware and control system are used to construct the device according to the function.The device meets the requirements of constant temperature and humidity,aseptic,portable,easy to combine with a microscope,and convenient to observe cells in real time.(4)Application of the bionic microfluidic chip on cell culture and tumor drug analysis.The bionic 2D cell culture microfluidic chips are used for various cell culture,and the cell growth curve,cell viability and single cell attachment area are analyzed to verify the applicability of the chip for cell culture.The arrangement of cells under different flow rates and distribution of cells under regionalized serum concentration are studied.A549 cells and Hela cells are parallel co-cultured using the 2D cell co-culture microfluidic chip,and the tumor targeting effects of folic acid-cholesterol-chitosan(FACC)nanoparticles on cells are studied.By combining with a Christmas tree-shaped concentration gradient generator,the apoptosis of A549 cells and Hela cells are studied under the nanoparticle drug folic acid-cholesterol-chitosan-paclitaxel(FACC-PTX).The 3D culture microfluidic chip is used for 3D dynamic culture of Hela cells,and compared with 2D static culture in terms of cell morphology,cell growth rate and cell viability.The results indicate that 3D dynamic culture conditions have obvious advantages.