Jin Matsumoto

Base-pair mapping by chemical force microscopy on nucleobase self-assembled monolayers

Self-assembled monolayers (SAMs) of double-chain disulfide derivatives of nucleobases (adenine and thymine) were formed on Au substrates in order to measure complementary hydrogen bonding by chemical force microscopy at the interfaces. Surface plasmon resonance measurements indicated that the formation of the nucleobase SAMs on Au surface was completed within 80 min. To measure adhesion force by atomic force microscopy (AFM), Au-coated AFM tips were modified with the nucleobase SAMs, too. SAM-modified Au substrates micro-patterned on quartz substrates were prepared for adhesion force mapping. The adhesion force between the complementary nucleobases is larger than that of the non-complementary combination. Electrochemical detection using a redox-intercalator was demonstrated for hybridization of single-stranded polynucleic acid with the nucleobase SAMs modified on Au electrodes.

CIRCULAR ARRANGEMENT OF AZOBENZENE CHROMOPHORES IN THE NUCLEOAMPHIPHILE MONOLAYER BY BASE-PAIRING WITH CYCLIC DNA

In order to construct chromophores arrays that precisely controlled their arrangement, monolayers of an azobenzene bearing nucleoamphiphile were prepared on various oligoDNA solutions. Monolayers of the amphiphilic adenine derivative bearing an azobenzene moiety (C12AzoC5Ade) were prepared on thymidylic acid tetramer (dT4) and octamer (dT8) solutions, and UV-vis reflection absorption spectra of the monolayers were measured to investigate aggregation structures of the azobenzene. The absorption maximum of the monolayer was blue-shifted on the dT4 solution and red-shifted on the dT8 solution. It shows that azobenzene groups in the monolayer have parallel orientation (H aggregate) on the dT4 solution. Though, azobenzene groups have head-to-tail orientation (J aggregates) on the dT8 solution. When monolayers of C12AzoC5Ade were prepared on the synthesized cyclic oligonucleotides, the absorption spectra were totally different from those of the corresponding linear oligonucleotides.

Photopolymerization of the Diacetylene Nucleobase Monolayers Controlled by Triplex Formation

Abstract Pressure-area isotherms of ternary component monolayers of nucleobase amphiphiles, octadecylcytosine (C18-Cyt) and diacetylene-containing adenine and thymine amphiphiles (DA-Ade, DA-Thy), were changed by addition of oligonucleotides, d(GT)15 or d(GGT)10, in the water subphase. Photopolymerization of diacetylene in the monolayer was strongly suppressed on the oligonucleotide subphase. This suggests that the oligonucleotide can act as a template for the diacetylene monomer arrangement via complementary hydrogen bonding at the air-water interface.