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Vascular endothelial growth factor (VEGF) was immobilized on substrata in photoreactive gelatin to control the adhesion and growth of vascular endothelial cells. The gelatin and VEGF were mixed in water and cast on a polystyrene dish or a silane-coated glass plate. The surface was then photoirradiated in the presence or absence of a photomask and washed. Toughness of the immobilized material was confirmed by ethanol treatment. Human umbilical vein endothelial cells (HUVECs) grew on the immobilized VEGF but not on a nontreated surface. Growth of HUVEC increased significantly with an increase in the amount of immobilized VEGF, and the effects were inhibited by treatment with anti-VEGF antibody. Thus, immobilized VEGF specifically interacted with HUVECs to permit growth in culture. Micropatterning of HUVEC cultures was also achieved using micropattern-immobilized VEGF. This patterning technique may be useful for the formation of blood vessel networks in vitro.

Various types of nanocomponents have been developed to construct a nanodevice or nanomachine. Here, we add a new nanocomponent that has the function of self-oscillation. A thermoresponsive polymer carrying a Ru complex, a catalyst of the Belousov-Zhabotinsky reaction, was synthesized and immobilized on a glass plate. Periodic turbidity changes in the aqueous solution of the polymer were observed, and nanoscale self-oscillation of the immobilized polymer was observed by a scanning probe microscope.

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Deoxyribozyme (DNAzyme) carrying peroxidase activity was immobilized on two types of particles and the enzymatic activity was measured. The DNA recognizing porphyrin were prepared according to Travascio et al. ([1998] Chem Biol 5:505-517) and the interactions with hemin were investigated by ultraviolet absorbance and circular dichroism spectroscopies. The DNA interacted with hemin and significant conformational change was induced by the interaction. Therefore, the end of this DNA was modified with a thiol group and it was immobilized on thiol-containing polysaccharide beads or on gold particles. The DNA immobilized on the gold particle showed activity catalyzing the peroxidation reaction. No significant reduction of activity was observed even after immobilization. The immobilized DNAzyme could be repeatedly utilized without significant loss of activity. In addition, heat treatment did not reduce the activity, although a protein enzyme, horseradish peroxidase, lost its activity after the heat treatment. The repertoire of DNAzyme is still currently limited. However, in the future the utilization of DNAzyme in the field of biotechnology will be important with the increase of discoveries of new functional DNAzymes.

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