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We designed novel peptide gemini surfactants (PG-surfactants), DKDKC12K and DKDKC12D, which can solubilize Photosystem I (PSI) of Thermosynecoccus elongatus and Photosystem II (PSII) of Thermosynecoccus vulcanus in an aqueous buffer solution. To assess the detailed effects of PG-surfactants on the original supramolecular membrane protein complexes and functions of PSI and PSII, we applied the surfactant exchange method to the isolated PSI and PSII. Spectroscopic properties, light-induced electron transfer activity, and dynamic light scattering measurements showed that PSI and PSII could be solubilized not only with retention of the original supramolecular protein complexes and functions but also without forming aggregates. Furthermore, measurement of the lifetime of light-induced charge-separation state in PSI revealed that both surfactants, especially DKDKC12D, displayed slight improvement against thermal denaturation below 60 °C compared with that using β-DDM. This degree of improvement in thermal resistance still seems low, implying that the peptide moieties did not interact directly with membrane protein surfaces. By conjugating an electron mediator such as methyl viologen (MV(2+)) to DKDKC12K (denoted MV-DKDKC12K), we obtained derivatives that can trap the generated reductive electrons from the light-irradiated PSI. After immobilization onto an indium tin oxide electrode, a cathodic photocurrent from the electrode to the PSI/MV-DKDKC12K conjugate was observed in response to the interval of light irradiation. These findings indicate that the PG-surfactants DKDKC12K and DKDKC12D provide not only a new class of solubilization surfactants but also insights into designing other derivatives that confer new functions on PSI and PSII.

BF(2) complexes containing tetracene and perylene moieties were synthesized as new types of electron-deficient arene compounds. These compounds exhibit long wavelength absorption and high electron affinities, as revealed through spectral and electrochemical studies, due to their quadrupolar structures represented by resonance contributors. The BF(2) complex containing tetracene exhibits an n-type semiconducting behavior. These compounds are new types of electron acceptors functionalized by BF(2) chelation.

Preparation of DPPC lipid monolayer in water trough has been done by dropping method and compared with compression method. Monolayer was studied by surface pressure isotherm, fluorescence microscopy, Brewster angle microscopy, and infrared external reflection spectroscopy. Results of these measurements showed that dropping method gave better results compared to compression method. In dropping method, transition from liquid expanded state to liquid condensed is gradual compared to sharp one in compressed method. During monolayer formation, adjustment and interaction between hydrophilic part of lipid and water and among hydrophobic part of lipid molecule are slow, stable, and more natural as worked out from surface area versus pressure isotherm. At a given molecular area, surface pressure is less compared to compression method thus monolayer is in more fluidic state in dropping method than compression method. The observation was supported by all techniques described above.

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Peptide-based gemini surfactants, called PG-surfactants, consisting of a tri- or tetra-Asp peptide core and acetylated dodecylamine-conjugated Cys residues at both the N- and C-terminal ends (D3C12 and D4C12), form a stable planar bilayer membrane on a solid support. From the DLS and TEM analyses, D3C12 and D4C12 have a tendency to form bilayer morphologies in a buffer solution, which reflects their tendency to form a stable planar bilayer membrane.

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