tion of individual protein molecules or complexes than an extended, homogeneous surface. Of course, this hypothesis needs to be tested by biological activity. ExperimentalSize-selected metal (Au) clusters, with size between 1 and 100 atoms, were generated by an RF (radio-frequency) magnetron sputtering, gas condensation [20,21] cluster beam source and mass selected to within 5 % by a novel, lateral time-of-flight mass filter to control the cluster size, as described previously [22]. The energetic beam of ionized Au clusters was deposited on a graphite substrate with sufficient kinetic energy to ªpinº the clusters to their individual points of impact on the surface. The underlying mechanism of pinning is the displacement of a surface carbon atom to create a reactive binding site which prevents the characteristic diffusion and aggregation of clusters observed at lower incident energies [15,16]. In this work we found that such monodispersed cluster films were stable not only at room temperature but also at temperatures up to 200 C. They are also stable when placed in an autoclave (130 C for 2 h in high pressure steam) to sterilize the surface. The Au 17 + clusters were produced with an Ar flow of 60 sccm and a He flow of 25 sccm (total gas pressure of 0.4 mbar). Typical sputtering parameters were: RF power 25 W; self-bias voltage of the target 372 V. The cluster samples were imaged in ambient conditions with a bench-top STM (DME Rasterscope 4000). Typical imaging parameters were 0.4 V and 0.4 nA (using mechanically cut Pt/Ir tips). All AFM measurements were collected from a Digital Instruments DI3100 equipped with a Nanoscope IIIa controller and a liquid cell holder. Commercial oxide sharpened silicon nitride tips with nominal spring constant of either 0.38 or 0.60 N m ±1 were used for imaging.

The self-assembly of triblock copolymers of poly(ethylene oxide-b-methyl methacrylate-b-styrene) (PEO-b-PMMA-b-PS), where PS is the major component and PMMA and PEO are minor components, provides a robust route to highly ordered, nanoporous arrays with cylindrical pores of 10-15 nm that show promise in block copolymer lithography. These ABC triblock copolymers were synthesized by controlled living radical polymerization, and after solvent annealing, thin films showing defect-free cylindrical microdomains were obtained. The key to the successful generation of highly regular, porous thin films is the use of PMMA as a photodegradable mid-block which leads to nanoporous structures with an unprecedented degree of lateral order. The power of using a triblock copolymer when compared to a traditional diblock copolymer is evidenced by the ability to exploit and combine the advantages of two separate diblock copolymer systems, the high degree of lateral ordering inherent in PS-b-PEO diblocks plus the facile degradability of PS-b-PMMA diblock copolymer systems, while negating the corresponding disadvantages, poor degradability in PS-b-PEO systems and no long-range order for PS-b-PMMA diblocks.