Fabrication of biomolecular nanostructures by scanning near-field photolithography of oligo(ethylene glycol)-terminated self-assembled monolayers.
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.
Montague
Matthew
M
Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, U.K.
Ducker
Robert E
RE
Chong
Karen S L
KS
Manning
Robert J
RJ
Rutten
Frank J M
FJ
Davies
Martyn C
MC
Leggett
Graham J
GJ
D006046:Gold / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D010084:Oxidation-Reduction / Q000528:radiation effects; D010777:Photochemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry; D014466:Ultraviolet Rays
D013438:Sulfhydryl Compounds; D011092:Polyethylene Glycols; D006046:Gold