Fabrication of Biomolecular Nanostructures by Scanning Near-Field Photolithography of Oligo(ethylene glycol)-Terminated Self-Assembled Monolayers

Abstract

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.

Nanoscale Biomolecular Structures on Self‐Assembled Monolayers Generated from Modular Pegylated Disulfides

“…Thus, a modular strategy was envisaged in which the more simple building blocks 3-5 were synthesised and then combined on the solid support 6. It was also envisaged that the internal amide bonds of 1 and 2, apart from acting as the link between the building blocks, would also impart improved SAM stability by virtue of lateral hydrogen bonding between the SAM units [44,45] in contrast to 11-mercaptoundecyl triA C H T U N G T R E N N U N G (ethylene) glycol (7), the material commonly used in the preparation of bioresistant SAM surfaces [20,24,26] which lacks the internal amide bond.…”

“…The fabrication of a SAM of 1 with amino-presenting features of 2 allowed the generation of protein patterns through both covalent and non-covalent immobilisation methods, a significant result since these promise to be effective methods for the fabrication of protein nano-features. [20,[56][57][58][59] It is expected that under optimum conditions, truly nanoscopic feature sizes as small as 9 nm may be fabricated. [20] The work shown in this report will be useful in the future development of biomolecular "nanoarrays" for high throughput screening and wider applications in biomedical diagnostics, biosensors, organic material electronics and the assembly of more complex three-dimensional structures.…”

“…Here, SAMs offer a straightforward route to the control of chemistry over macroscopic areas. [6,7] When combined with a lithographic technique, [3,[8][9][10][11][12][13][14] such as electron beam lithography, [15,16] dip-pen nanolithography [11,17,18] and scanning nearfield photolithography (SNP), [14,19,20] patterning of SAMs can be achieved with nanoscale resolution.…”

Micro- and Nanostructured Poly[oligo(ethylene glycol)methacrylate] Brushes Grown From Photopatterned Halogen Initiators by Atom Transfer Radical Polymerization

“…9͒ and self-assembled monolayers of oligo͑ethylene glycol͒ terminated alkanethiolates. [10][11][12] However, polymer patterning is difficult on small length scales, and while self-assembled monolayers of alkanethiolates, [13][14][15][16][17][18][19] alkylsiloxanes, [20][21][22] and alkylphosphonates [23][24][25][26] have been patterned by a variety of methods, they are not without problems. Alkanethiolate selfassembled monolayers ͑SAMs͒ are rarely defect-free and exhibit limited oxidative stability, while siloxane films exhibit low degrees of order.…”

Herstellung von Proteinmustern durch Schreiben in proteinabweisende Matrizen

“…Röntgenphoto-elektronenspektroskopie(XPS)-Daten (siehe Abbildung 2 a sowie Abbildung SI1 der Hintergrundinformationen) zeigen, dass der OEG-Teil solcher Filme gegenüber Elektronenbestrahlung sehr empfindlich ist (ein ähnliches Verhalten wurde kürzlich für UV-Bestrahlung beobachtet). [14] Diese Gruppe wird durch die Bestrahlung in hohem Maße verändert, und das sogar schon bei sehr niedrigen Dosen ( 1 mCcm À2 ), bei denen sowohl der aliphatische Teil als auch die Thiolat-Ankergruppe der SAM größtenteils intakt bleiben, sodass die vollständige Anbindung der Moleküle an das Substrat bewahrt wird. [13] Durch den elektroneninduzierten Abbau der OEG-Kette nimmt die effektive Dicke der OEG-SAMs im Zuge der Bestrahlung allmählich ab (Abbildung 2 b).…”