The Study Of Cell Attachment / Detachment Behaviors On Thermoresponsive Microgel Patterned Surface

Enzymolysis approach could damage proteolytic enzymes and cytoactive decreases,the utilization of poly(N-isopropylacrylamide)(pNIPAAm)thermoresponsive coating could overcome this defect and gain access to harvest intact cell sheet.However,the thermoresponsive coating that used are continuous rencently,wheather the cell could detach from the discontinuoused thermoresponsive coating or not? If it could,wheather the critical value exists or not.To resolve the problem above,this work choose the poly(N-isopropylacrylamide)(pNIPAAm)microgels as matrix,spinning on the glass that pretreated by PEI to form microgel monolayer,then fabricating the patterned microgel surface through negative microcontact method to investgate the influence of patterned cell adhension surface to cell detachment.The determination of the critical value of single cell's detachment.This part of work establish the diameter of 3-10?m microgel circle and the space between the circle is 9-20?m,NIH3T3 mouse fibroblast cells were then cultured on the patterns with different thermo-island diameters and gaps to study the single cell's detachment behavior.It was found that cells could detach not only from these discontinuous thermoresponsive coatings,but also from the patterned surfaces with the thermoresponsive area being as low as 20% of the cell spread area.The determination of the critical value of cell sheet's detachment.Unlike the single cell,the interaction between cell and substrate are more complex because of cell-to-cell interaction.we hypothesize that if the cell-to-cell interaction is strong enough to retain the whole cell sheet from disintegration,the cell segments growing on the thermoresponsive strips may drag the cell segments growing on the cell-adherent gaps to detach,ending with a whole freestanding and transferable cell sheet.Critical value concerning the width of the thermoresponsive strip and its ratio to the non-thermoresponsive gap may exist.To obtain this critical value,a series of strip patterns were prepared.The results unraveled that COS7 cells preferentially attached and proliferated on non-thermoresponsive gaps to form patterned cell layers and they subsequently proliferated to cover the microgel strips to form a confluent cell layer.Within the 500?m,intact COS7 cell sheets could be recovered when the width of the thermoresponsive strip is no smaller than that of the non-thermoresponsive gap.Other cells such as HeLa,NIH3T3,293 E,and L929 could grow similarly.that is,they showed initial prefer to cover the non-thermoresponsive gaps and then migrated to cover the entire patterned surface.However,it was difficult to detach them as cell sheets due to the weak interactions within the cell layers formed.In contrast,when COS7 and HeLa cells were cultured successively,they formed the cocultured cell layer that could be detached together.These freestanding patterned cell sheets could lead to the development of more elaborate tumor models for drug targeting and interrogation.