Atomic force microscopy at high temperature resolution (DeltaT < or approximately 0.1 K) provided a quantitative structural calorimetry of the transition from the fluid (Lalpha)- to the gel (Pbeta')-phase of supported dimyristoylphosphatidylcholine bilayers. Besides a determination of the main transition temperature (T0) and the van't Hoff transition enthalpy (DeltaHvH), the structural analysis in the nm-scale at T close to T0 of the ripple phase allowed an experimental estimation of the area of cooperative units from small lipid domains. Thereby, the corresponding transition enthalpy (DeltaH) of single molecules could be determined. The lipid organization and the corresponding parameters T0 and DeltaHvH (DeltaH) were modulated by heptanol or external Ca2+ and compared with physiological findings. The size of the cooperative unit was not significantly affected by the presence of 1 mM heptanol. The observed linear relationship of DeltaHvH and T0 was discussed in terms of a change in heat capacity.

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The line-scan mode is applied in aqueous suspensions of NHS-nanogold and NHS -nanogold-lysozyme conjugates to generate tip-induced linelike pattern with a width in the nanometer scale. With increasing ionic strength the spontaneous adsorption of the particles to the mica surface can be reduced. The reduction causes an increase in the processing time, which is necessary to form a continuous line composed of the respective particles. The line width increases with increasing loading force. For NHS-nanogold, a minimal line width of about 40 nm could be achieved. The results were used to connect two opposite macroscopic gold contacts about 5 µm apart by a line of NHS-nanogold, which appeared to be of continuous structure down to the nanometer scale, according to the corresponding topography.

Nanostructures of lysozyme molecules and lysozyme-nanogold conjugates were generated by atomic force microscopy in contact-, tapping- and force-distance- mode on mica in aqueous solution. In contact mode at high ionic strength, adjusted lysozyme concentration and lower loading force a monolayer of defined structure and orientation of lysozyme can be formed by the scan process of the tip. A lateral resolution of the monolayer of about 80 nm could be achieved. At larger loading forces besides a lysozyme monolayer also 3D- aggregates could be generated in parallel. In force-distance mode the volume of 3D-aggregates was studied as function of lysozyme concentration, loading force and number or frequency of up- and down-movement of the tip. Also in tapping mode 3D-aggregates were generated at the selected incubation conditions. Application of the linescan mode for solutions of nanogold or lysozyme-nanogold conjugates allowed the formation of monlayers of linear shape with lateral resolution of about 35 nm on mica. Nanogold line-structures could be connected to macroscopic gold contacts. It is postulated that adjustment of electrostatic interaction between lysozyme and substrate and the applied loading force is critical for monolayer formation. Different to the underlying mechanism of the well-established dip-pen nanolithography (DPN) (Piner et al., 1999) for the presented method of diving tip nanowriting (DTN) adsorption of the molecules from the aqueous bulk phase to the tip and thereafter the flow to the mica surface is discussed. DTN could be used to either contact proteins electrically or to form preaggregates for protein crystallization (Wiechmann et al.