Near‐Field Lithography by Two‐Photon Induced Photocleavage of Organic Monolayers

Abstract

We prove that the enhanced electromagnetic near-fi eld around metallic nanostructures can be used for localized two-photon-induced activation of surfaces, obtaining a defi ned chemical pattern with nanometric resolution. Gold nanoparticles (Au-NP) are deposited on glass slides that were modifi ed with a polysiloxane layer containing a nitroveratrylcarbonyl (NVoc) photoremovable group. Upon illumination with a femtosecond laser, the NVoc entity is removed. Due to the electromagnetic fi eld enhancement of the nanoparticles, the threshold of this process is lowered in the nm-scale vicinity of the metal structures. Upon cleavage, an amine functional group is released, which can be used to site-selectively bind species with complementary chemical functionality on the surface. This method can be utilized for sub-wavelength chemical structuring.

Wavelength-Selective Caged Surfaces: How Many Functional Levels Are Possible?

“…The photosensitive silanes 1, 3,5,8,13,14, and 17 were obtained and isolated in good yields following the synthetic route specified in Scheme 1. The detailed synthetic protocols are included as Supporting Information.…”

Photocleavable epoxy based materials

“…[6][7][8] The photochemistry of o-NB alcohol derivatives has also gained increased attention in the side functionalization of copolymers and in the preparation of photo-responsive selfassembled monolayers. [9,10] In an effort to combine photodegradable properties with good biocompatibility and low cytotoxicity the development of o-NB-based hydrogels comprising photocleavable crosslinks presents a unique opportunity. [11,12] In particular, biocompatible polymer networks based on poly(ethylene glycol), dextran, agarose or hyaluronan bearing o-NB-linkers have been developed which are promising materials for tissue engineering and controlled drug delivery.…”

Soft Ultraviolet (UV) Photopatterning and Metallization of Self-Assembled Monolayers (SAMs) Formed from the Lipoic Acid Ester of α-Hydroxy-1-acetylpyrene: The Generality of Acid-Catalyzed Removal of Thiol-on-Gold SAMs using Soft UV Light

“…Compared to deep UV photopatterning of SAMs, or the production of patterned SAMs through microcontact printing, one of the advantages of using soft UV photopatterning is that, by exploiting double quantum processes, it is possible to create SAMs that are patterned on the nanometer scale; on a scale less than that of the wavelength of the light. 1,2,19 Another advantage of soft UV photochemistry comes in terms of drug delivery using up?converting nanoparticles. Biological tissue is relatively transparent to light at ~800 nm and, since up?converting nanoparticles can convert ~880 nm to ~365 nm light, this can be used to trigger release of drugs from SAM layers bound to the particles through soft?uv photocleavable linkers.…”