Const Iction Of Biomimctic Hydrophobic And High Adhesive Silk Fibroin Film And Study On Its Controlling Of Cell Microdroplet

The growth environment of cells in vivo is a three-dimensional environment controlled by highly organized biophysical structure and multiple factors.The study of the interaction between cells and growth matrix which affected by surface wettability is a very significant research topic.Surface wettability is affected by the microscopic morphology and chemical properties of the material surface,which can further adjust the response of the biological system.Based on the hydrophobic properties,materials with specific biological functions have been widely used in the field of biomedicine.Learning from the nature,by simulating the "rose petal effec",materials can be given special characteristics of both hydrophobicity and high adhesion,which provide the possibility for droplet control and multi-dimensional culture of cells.It is also a very important research area at present.Silk fibroin is accepted by FDA in some medical applications for its nonimmunity and excellent biological properties.In this thesis,based on good biocompatibility of silk fibroin materials,we focused on constructing silk fibroin film material with rose petals-like micro/nanostructure by replica molding technology.The best solution for insoluble post-treatment of silk fibroin films with biomimetic micro/nano structure was explored.The effects of silk fibroin's wettability on cells growth behavior under different culture angles(0°,90°,180°)were investigated,and the cells adhesion and proliferation under the condition of resisting gravity were revealed.The research lays theoretical and powerful foundation for the application of micro-platform-based biochip technology and high-throughput screening.The main results of this dissertation are outlined as follows:(1)Using polydimethylsiloxane(PDMS)as an elastic template,silk fibroin film with rose petals-like micro/nano structure was successfully prepared by replica molding technology.The influence of methanol treatment>ethanol treatment and water vapor annealing treatment on the physicochemical properties of silk fibroin film were systematically investigated.The results indicate that water vapor annealing treatment can not only promote the stability of materials effectively,but also maintain the micro/nanostructure of biomimetic silk fibroin films.The best insoluble post-treatment on the sample is the water vapor annealing treatment under the condition of 65 ? for 6h.(2)The results of surface wettability indicate that compared with natural rose petals and flat silk fibroin film,the prepared silk fibroin film with rose petals-like micro/nano structure can reach a water contact angle of 141.4±0.21° and an adhesion force of 351.1±25.6 ?N,showing the "rose petal effect" of hydrophobic and high adhesion features.At the same time,the contact model of silk fibroin film with biomimetic micro/nano structure was proposed,which conformed to the Cassie impregnating contact model.The liquid can permeate into the micropapillary structure,but cannot infiltrate through the nano-fold structure.(3)The results of two-dimensional(0°)in vitro cell culture experiments show that cells adhere to the middle of micropapillary structure in the early stage of culture,and then gradually cover the nano-fold area,which closely related to the surface contact model(Cassie impregnating state).In the early stage of cell culture(6 h and 1 d),the petals-like micro/nano structure of silk fibroin film can provide anchor points for cells adhesion,thereby promoting cells adhesion and proliferation.In the mid-to-late period of cell culture(3 d and 7 d),the hydrophobicity feature on the petals-like silk fibroin film could prevent the cells from proliferating and spreading,and the cells cannot obtain sufficient growth space which resulting in a slower proliferation rate.(4)The results of in vitro cell culture experiments at different angles(90°,180°)against the gravity indicate that the number of cells on the surface of prepared samples was significantly reduced due to the effect of gravity on the cells adhesion.And due to the special biomimetic micro/nano structures of silk fibroin film,it can obviously promote the firm adhesion of cells on the surface of materials,which means that cells can resist the effect of gravity to a certain extent.Cells still adhered well to the materials surface under 90° and 180° culture conditions.Especially under 180° culture condition,cells grown on the surface of rose petals-like silk fibroin film can aggregate and proliferate in the vertical direction to form a three-dimensional cell aggregation sphere.(5)The internal mechanical model of cell droplets adhered to the surface of rose petals-like silk fibroin film under different gravity was established.It is considered that when the gravity of the cell aggregate is greater than the internal fluid force,cells will sink to the bottom of the droplet.Due to the "rose petal effect" on the surface of rose petals-like silk fibroin film,under the condition of anti-gravity,the hydrophobic and highly adherent surface characteristics can improve the stability of the interface between cell droplet and the material surface.The micro/nano structure on the surface of rose petals-like silk fibroin film could provide more anchor points for the cells,which enhance the cell's adhesion and enables the cells to proliferate against the influence of gravity to form cell clusters.