Montague Matthew, Ducker Robert E, Chong Karen S L, Manning Robert J, Rutten Frank J M, Davies Martyn C, Leggett Graham J
Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, U.K.
Langmuir. 2007 Jun 19;23(13):7328-37. doi: 10.1021/la070196h. Epub 2007 May 19.
The UV photo-oxidation of oligo(ethylene glycol) (OEG)-terminated self-assembled monolayers (SAMs) has been studied using static secondary ion mass spectrometry, X-ray photoelectron spectroscopy, contact angle measurement, and friction force microscopy. OEG-terminated SAMs are oxidized to yield sulfonates, but photodegradation of the OEG chain also occurs on a more rapid time scale, yielding degradation products that remain bound to the surface via gold-sulfur bonds. The oxidation of these degradation products is the rate-limiting step in the process. Photopatterning of OEG-terminated SAMs may be accomplished by using a mask and suitable light source or by using scanning near-field photolithography (SNP) in which the mask is replaced by a scanning near-field optical microscope coupled to a UV laser. Using SNP, it is possible to fabricate patterns in SAMs with a full width at half-maximum height (fwhm) as small as 9 nm, which is approximately 15 times smaller than the conventional diffraction limit. SNP-patterned OEG-terminated SAMs may be used to fabricate protein nanopatterns. By adsorbing carboxylic acid-terminated thiols into oxidized regions and converting these to active ester intermediates, it has been possible to fabricate lines of protein molecules with widths of only a few tens of nanometers.
采用静态二次离子质谱、X射线光电子能谱、接触角测量和摩擦力显微镜等方法，对以低聚乙二醇（OEG）为端基的自组装单分子层（SAMs）的紫外光氧化过程进行了研究。以OEG为端基的SAMs被氧化生成磺酸盐，但OEG链的光降解也在更快的时间尺度上发生，产生的降解产物通过金硫键仍与表面结合。这些降解产物的氧化是该过程中的限速步骤。以OEG为端基的SAMs的光图案化可以通过使用掩膜和合适的光源来实现，或者通过使用扫描近场光刻（SNP）来实现，其中掩膜被与紫外激光耦合的扫描近场光学显微镜所取代。使用SNP，可以在SAMs中制造半高宽（fwhm）小至9 nm的图案，这比传统的衍射极限小约15倍。SNP图案化的以OEG为端基的SAMs可用于制造蛋白质纳米图案。通过将羧酸端基硫醇吸附到氧化区域并将这些区域转化为活性酯中间体，已能够制造出宽度仅为几十纳米的蛋白质分子线。
