Advanced materials composed of biological and artificial components are synthesized for development of environmentally friendly energy collection and conversion systems. By combination of organic synthetic chemistry, polymer chemistry, and biotechnology, novel synthesis method will be established and materials using biological and artificial elements will be achieved by their chemical fabrication, and the characterization of the interfaces between biological and artificial elements for highly efficient energy collection and conversion or biological functions. Especially our team will establish a new methodology, a chemically extended molecular evolutionary engineering as an “Emergent Chemistry” to create a specific ally functionalized polymer by screening of random sequence of polymer library containing functional monomers.
Bioinspired underwater adhesive biopolymers for biologically active materials
Artificial materials have no biological functions, although they are important for medical devices such as artificial organs and matrices for regenerative medicine. Therefore, for more reliable biomaterials, biocompatibility is required to enhance the connection between materials and biological components. Our team has developed new bioactive materials by immobilization of biologically macromolecules (polypeptides) on the surfaces. For example, we designed cell activative materials by simple coating of polypeptides containing sequence of growth factor proteins with a key amino acid, 3,4-dihydroxyphenylalanine, of underwater adhesive proteins, which is secreted from mussel for adhering to rocks. The adhesive polypeptides were prepared by the bioorthogonal approaches including genetic recombination, enzymatic method, and solid phase synthesis. They formed nanolayers on various substrates involving organic and inorganic materials to conveniently provide biological surfaces. Through the direct activation of cognate receptors on interactive surfaces, the materials enhanced the cell activities more than soluble growth polypeptides.
Creation of bioactive surface by underwater-adhesive biological macromolecues prepared according to bioorthogonal approaches
Solution-processed substrate-free thermoelectric films
Single-walled carbon nanotubes (SWCNTs) are advantageous for energy-conversion materials because of their large electrical conductivity, mechanical strength, and light weight. Unfortunately, SWCNTs exhibit poor processability owing to inevitable aggregation. We demonstrated substrate-free thermoelectric (TE) films using solution-processed methodology. Thermally cleavable polythiophene derivatives containing carbonate groups and solubilizing groups in side chains were synthesized. The polymer showed noncovalent modification of SWCNTs that led to a dispersed polymer/SWCNTs solution. This dispersed solution allowed a solution-processable polymer/SWCNTs composite film. The insoluble composite film was obtained by the thermal cleavage of the solubilizing group in a solid state. The substrate-free polymer/SWCNTs composite film prepared by solvent evaporation exhibited the TE property. These results are expected to be useful for preparation of flexible TE devices.
Schematic illustration of thermally cleavable polythiophene for dispersed SWCNTs composite and an insoluble SWCNTs film.
Polypeptide self-assembly directed by the addition of cosolvents
