Research

“Supramolecule” is a molecular assembly of designed molecules through non-covalent bonds such as hydrophobic interaction, electrostatic interaction, and hydrogen bonds. Supramolecules exhibit interesting properties those are different from single molecule. Peptides are very attractive as molecular elements that create supramolecular assemblies with controlled nanometer-sized structures, because we can use various amino acids with different properties as building blocks in peptide design.
We have successfully developed a variety of nanostructures such as nanometer-sized fibers, tapes, ribbons, and tubes by combination of various amino acids. In addition, we are developing supramolecular peptides that integrate fluorescent dyes and transition metal ions in nanostructures and applying them to nanomaterials that function as optical materials and catalysts.

Amphiphilic designed peptides can form supramolecular structures in aqueous media. We have successfully developed supramolecular peptides that form uniformly sized nanofibers in water and have succeeded in creating hydrogels (peptide gels). Our peptide gels are available for 3D culture of various cells inside of gels due to their high cell compatibility. In addition, peptide gels can be functionalized by conjugation with various bioactive peptides which control cellular functions. The functionalized peptide gels are promising materials to construct organ models (organoids) in a test tube. We have applied the functionalized peptide gels to cancer tissue models which are useful for drug test and mechanism analysis of malignant transformation of cancer cells.

The medical environment has advanced greatly in recent years, because various therapeutic agents (modalities) become available including not only small molecule drugs but also antibody drugs. The development of new modalities is essential to the advancement of medical care. In recent years, various techniques have been established to screen specific inhibitory peptides for pathogenic proteins from more than 10 million different peptide libraries, and peptide drugs are attracting attention as a new modality. The phage display method, which was awarded the Nobel Prize in Chemistry in 2018, is widely used as a leading method for peptide drug discovery.
We have established a new method to screen superior inhibitory peptides more efficiently than conventional methods by chemical modification of functional molecules such as small molecule drugs onto peptide libraries constructed by phage display method. We are developing peptide drugs targeting various pathogenic proteins using our modified phage display method.

Peptides can be chemically synthesized like small molecule drugs. In addition, optimally modified peptides exhibit therapeutic effects comparable to antibodies. On the other hand, practical use of peptides as drugs requires many aspects to be improved such as increasing their inhibitory activity and specificity against pathogenic proteins and providing them with in vivo stability and biocompatibility.
We are developing nanoparticle-based drugs with dramatically improved binding activity and specificity due to the cluster effect by accumulating many peptides that bind to disease-related proteins on the surface of biocompatible silica and gold nanoparticles. In addition, we have developed nanoparticles modified with both small-molecule anti-cancer drugs and peptides binding to biomolecules on the surface of cancer cells, because they are expected to work as drug delivery carriers to deliver anti-cancer drugs to cancer cells.