Hiroshi Nakashima

We fabricated a heterogeneous supported lipid bilayer (SLB) by employing binary lipid mixtures comprising a saturated acyl chain DSPC and an unsaturated acyl chain nickel-chelating lipid. By using the specific adsorption properties of histidine-tagged proteins (His-tagged GFPs) in relation to nickel-chelating lipids, we demonstrated protein pattern formation on the SLB corresponding to the phase separation pattern of the SLB. In addition, by using a lipid mixture consisting of an unsaturated acyl chain DOPC and a nickel-chelating lipid, and His-tagged GFPs, we succeeded in transporting the proteins along a hydrophilic micropattern on a SiO₂ substrate. The protein transport is induced by the self-spreading behavior of a fluid SLB with a kinetic spreading coefficient β = 10.4 μm² s⁻¹. This method provides a guide for strategically carrying various biomolecules to specific positions by using a soft biointerface on a solid surface. In addition, the results demonstrate the importance of using techniques that allow the controlled manipulation of biomolecules based on the static or dynamic properties of the SLB platform.

Surface-modified gold nanorods (Au NRs) with 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) were synthesized, and their self-assembled structures on a silicon substrate were observed using a scanning electron microscope (SEM). The Au NR−DPPTE complex formed characteristic one- and two-dimensional self-assemblies induced by intermolecular interactions of surface-anchored lipids via simple drying process. The interparticle distance between neighboring NRs was uniform at around 5.0 nm, which was consistent with the thickness of the lipid bilayer. Furthermore, we observed the anisotropic configurations of the NR complex, preferentially oriented in a lateral or perpendicular fashion, in a two-dimensional assembled structure dependent on the interfacial hydrophilicity or hydrophobicity of the silicon surface.

Gold nanorods (NRs) mixed with crown ether derivatives exhibited the efficient and selective recognition of Na⁺ and K⁺ ions, which were detected by localized surface plasmon absorption in response to dispersed and aggregated gold NRs. Furthermore, in the aggregates preferential end-to-end or side-to-side assembly of NRs was observed which was dependent on the additive concentration.