APPLICATION OF BIOMATERIALS IMMOBILIZED WITH BIOSIGNAL MOLECULES

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Approaches for controlling the interface between tissue or cells and biomaterial can be divided into two categories. One is biolization of materials another chemical modification.Biolization invloves immobilization of anticoagulant or hybridization of blood endothelial cells for blood-compatibility, or immobilization of cell adhesive reptide for cell adhesives. In addition, immobilization of cell growth factor proteins enhances cell growth. The immobilization of biosignal proteins enables biomaterials to regulate various functions of cells, such as differentiation, secretion, and motility.Chemical modification involves surface hydrophilization or hydrophobilization, or electrochemical modification. Recent progress of polymer science has enabled space-time control of material surface. The position of cells can be regulated by photo-lithographic modification of the surface and the attachment and detachment of cells can be controlled by temperature manipulation of a thermo-sensitive polym … More er.Herein the surface was biolized for growth enhancement and differentiation promotion. In addition, space-time controlled intelligent biomaterials were achieved by the combination of biological and chemical approches. The intelligent biomaterials will be useful not only for medical applications but also for fundamental methodologies of biosensors and nano-biotechnology.Surface biolization was achieved by immobilization of cell growth factor proteins, insulin and epidermal growth factor (EGF). EGF is a membrane-bound growth factor which can stimulate cells without diffusion in medium by "juxtacrine stimulation". Immobilized insulin and EGF enhanced cell growth more than free insulinor EGF.In the culture of pheochromocytoma (PC12) cells, the immobilized EGF promoted neural differentiation but did not enhance the growth, although free EGF enhanced growth. The stimulation mode (juxtacrine and paracrine) switched the gene expression.Time-controlled intelligent biomaterial was prepared usinf thermo-sensitive polymer. By combination with insulin, the biomaterial enhanced cell growth and the grown cells were detached by lowering temperature.Spatial controlled biomaterial was achieved by pattern immobilization of thrermo-responsive polymer, insulin, and EGF.Selective detachment of growth cells was observed on the micro-patterned thermo-responsive polymer at a low temperature. Selective signal transduction was observed on th specific area immobilized with insulin or EGF.The technique was useful for visualization of juxtacrine stimulation by immobilized biosignals. Less