Preparation And Characterization Of Chitosan/Bovine Serum Albumin Composite Micropatterns By Soft Lithography

Controlling cell orientation and morphology by micropatterned substrates is one of hot topic in biomedical engineering. Cells can respond to micrometer scale, and even nano-scale, surface topography. Cell shape, orientation, growth and differentiation are also affected by surface texture of materials. Composite micropatterns were multifunctional biomaterials that co-patterned two or more types of molecules on one substrate. Thus, it can employ the advantage of components.In this study, we developed a new process that can prepare chitosan/bovine serum albumin (CS/BSA) composite micropatterns by soft-lithography on silicon substrates. CS is a basic polysaccharide in the nature that has good biodegradability, renewable ability and antibacterial ability. BSA is a serum protein that has numerous biochemical applications. Polydimethylsiloxane (PDMS) microstamps were used to transfer micropatterns from the micromachined silicon mold to the hydroxylated silicon wafers. CS/BSA composite micropatterns, BSA micropatterns and CS micropatterns were successfully fabricated on silicon surfaces by micro-transfer molding and replica molding technique.The antibacterial test was used to evaluate the antibacterial effect of CS/BSA composite micropatterns. The results showed that the CS/BSA composite micropatterns were effectively against two types of bacteria, Escherichia coli and Staphylococcus albus. The osteoblast (Sprague-Dawley rat) culture indicated that CS/BSA composite micropatterns could strongly influence cell behavior. Cells selectively adhered in the CS region at intial culturing stage, and then they gradually spread to the BSA region. The microgrooved surfaces had strong contact guidance effect on cell orentation. Cells tended to be parallel to the microgrooves when they were cultured on BSA microgrooves and CS microgrooves surfaces, They began to attach on the ridges of microgrooves, grew along the direction of microgrooves, and then spread to the bottom of microgrooves. This tendency was stronger on the microgrooves with smaller width. The cells on plane samples had random growth directions. The proliferation and differential rate of cells on microgrooved surfaces is lower than that on plane surface and higher than that on microdot-patterned surfaces, which indicated that micropatterns had complicated effects on cell behaviors. This study provides valuable guidance for the design of the biomaterial surfaces.