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Murine 3T3 fibroblasts and primary human osteoblasts have been cultured on self-assembled monolayers (SAMs) formed by the adsorption of alkanethiols of varying terminal group and alkyl chain length on gold. It has been found that the interactions of both cell types with SAMs are influenced by surprisingly subtle changes in adsorbate structure. Both the nature of the adsorbate terminal group and the length of the alkyl chain have a significant influence on cellular attachment and growth. For both cell types, attachment and growth on the carboxylic acid terminated SAMs was extensive and was accompanied by a high degree of cell spreading. In contrast, attachment and growth on long-chain methyl terminated SAMs were poor. Attachment and growth on short-chain methyl terminated SAMs were intermediate, with reasonable numbers of attached cells being observed and some degree of cell spreading. Sharply contrasting behaviour was observed for the two cell types when cultured on hydroxy terminated SAMs. It was found that fibroblasts attached poorly to these surfaces, while osteoblasts attached and grew nearly as successfully on short-chain hydroxy terminated SAMs as on carboxylic acid terminated SAMs. Osteoblasts attached less well to long-chain hydroxy terminated SAMs, but better than to methyl terminated SAMs.

Static secondary ion mass spectrometry (SIMS) has been used to investigate the degradation of self-assembled monolayers (SAMs) of alkanethiols subjected to bombardment by keV electrons. Because of its remarkable structural specificity, SIMS revealed significant structural modifications to the SAMs following irradiation. Both positive and negative ion spectra exhibited dramatic changes after exposure of SAMs to electron bombardment. In the positive ion spectra, peaks were observed between m/z 100 and 200 that were attributed to polycyclic aromatic ions with masses greater than the adsorbate molecule. These species are the result of interchain crosslinking initiated by electron impact. In the negative ion spectra, gold-molecular clusters disappeared after only small doses of electrons, attributed to the rapid oxidation of thiolates to disulfides. After doses as high as 3×10 17 electrons cm –2 , there were still significant levels of sulfur at the surface along with graphitised carbonaceous material. It was concluded that keV electron impact leads to only slow removal of material from the SAM. These data illustrate the power of SIMS for probing surface reactions in SAMs.

The combination of wettability, X-ray photoelectron spectroscopy and scanning force microscopy has been used to analyse the changes to the surface after plasma treatment of poly(ethylene terephthalate) film. Calculations on contact angle data with a combination of polar and non-polar liquids have shown that argon plasma treatment considerably enhances the work of solid-(polar) liquid adhesion and the surface free energy of the films due to the creation of acidic and basic functions on the polymer surface. In contrast, Lifshitz-van der Waals (apolar) interactions decrease slightly as a consequence of plasma-induced chain-scission. We present the first study of a plasma-treated polymer by chemical force microscopy. Plasma-modified surfaces exhibit substantially higher friction than untreated material and are more easily disrupted by the movement of the tip during scanning. Friction is reduced when methyl-functionalised tips are employed. There is a correlation, on plasma treatment, between the rapid increases in surface friction probed by lateral force microscopy and surface free energy probed by wettability and X-ray photoelectron spectroscopy. The modified mechanical properties and polar group incorporation both result from scission of polymer chains and contribute to the lateral force contrast.

The use of scanning near-field photolithography (SNP) to fabricate DNA nanostructures is described. Two different strategies were employed to generate nanoscale features in oligo(ethylene glycol) (OEG) terminated alkylthiolate self-assembled monolayers (SAMs) on gold. At long exposure times, complete photooxidation of the SAM molecules enabled their displacement by amino-terminated thiol molecules, which were subsequently used to attach ss-DNA molecules; while short exposure times resulted in partial photochemical conversion of the terminal OEG group of the adsorbate to an aldehyde group facilitating the direct attachment of amino-DNA molecules. Arrays of DNA functionalized metal-nanoparticles were then assembled onto the ss-DNA patches through specific DNA hybridization. This methodology provides a facile approach for the assembly of bio-functionalised nanoparticles onto nanofeatures embedded in an inert background and will prove useful in biosensing applications.

Morphological and quantitative frictional measurements have been carried out on cotton fibres in dry air and in a liquid environment using friction force microscopy (FFM). Height and friction images acquired by FFM revealed that the cotton surface was damaged over 20 detergent-only wash cycle, but the inclusion of conditioner in the detergent formulation was found to cause a reduction in the amount of damage. The distribution of the fabric conditioner at the surface was examined by static secondary ion mass spectrometry (SSIMS). The friction–load relationship was found to obey Amontons' law in both dry air and water. The coefficient of friction increased with the number of wash cycles, and was reduced by treatment with fabric conditioner. Similar trends were observed in the variation in surface properties with wash treatment for measurements made in both air and liquid. To model the attachment of microencapsulate onto fibre surface, a poly(methyl methacrylate) (PMMA) encapsulate has been attached to the AFM cantilever to measure the frictional force. The same trend in the coefficient of friction was observed to that of measured by normal AFM cantilever.

Exposure of Langmuir–Blodgett (LB) films of a C60 adduct supported on silicon wafers to UV light leads to cross-linking of the C60 moieties, which are resistant to removal by solvent exposure, whereas unexposed moieties are readily removed. This process provides a convenient and simple route for the fabrication of highly conjugated surface-attached structures, with dimensions ranging from micrometres (using masks) to a few tens of nanometres using light emitted from a scanning near-field optical microscope (SNOM). The SNOM writing velocity was found to significantly affect the lateral resolution and the height of the three-dimensional nanostructures. Increasing the writing velocity from 0.3 to 2 μm s−1 resulted in a decrease in the width of the structures from 240 nm to 70 nm (corresponding to the SNOM aperture diameter), respectively, and a reduction in the height from 8 nm (the thickness of the original film) to 3 nm, respectively. This approach provides a simple, direct route to surface-bound nanometre scale assemblies of C60.