Photolithography of self-assembled monolayers: optimization of protecting groups by an electroanalytical method

Abstract

Patterned surfaces presenting a high density of chemically reactive functional groups can be prepared through photolithography of self-assembled monolayers (SAM). In this paper, we report the synthesis and the evaluation of three reagents that can be used in SAM-photolithographic applications. These reagents are made up of a triethoxysilylpropylamine moiety in which the amine is temporarily blocked by photolabile protecting groups: NVOC (0-nitroveratryloxycarbonyl), ONB (0-nitrobenzyl), or DDZ (a,a-dimethyl-3,s-dimethoxybenzyloxycarbonyl). The presence of the triethoxysilyl group allows selfassembled monolayer formation. Release of chemically reactive amino groups is achieved by irradiation of the surface. An electroanalytical method was developed and used to monitor and optimize the three steps of the methodology occurring on surfaces: monolayer formation, photodeprotection, and subsequent functionalization of the released amino groups. Quantitative information on the efficiency of the photodeprotection step was obtained by this method. It was found that the DDZ group is superior to the ONB and NVOC photolabile protecting groups for SAM-photolithographic applications. Percentages of liberated amino groups are generally above 50% with the DDZ group, while they are generally inferior to 25% and 2% for NVOC and ONB, respectively. These differences are attributed to the destruction of some of the released amino groups through a subsequent reaction with the photoproduct, o-nitrosobenzaldehyde for ONB and 3,4-dimethoxy-6-nitrosobenzaldehyde for NVOC, and to partial loss or destruction of the monolayer during prolonged irradiations.Key words: self-assembled monolayers, surface modification, photolithography, photolabile protecting groups, cyclic voltammetry.R6umC : Des motifs prCsentant une haute densite de groupes fonctionnels chimiquement rCactifs peuvent Stre prCparCs sur des surfaces i l'aide de la photolithographie de monocouches auto-assemblCes (MAA). Dans cet article, nous relatons la synthkse et 1'Cvaluation de trois rCactifs pouvant Ctre utilisCs dans des applications de la photolithographie-MAA. Ces rCactifs sont constituCs d'un fragment triCthoxysilylpropylamine dont la fonction amine est temporairement bloquCe par des groupement protecteurs photolabiles : NVOC (0-nitrovCratryloxycarbonyle), ONB (0-nitrobenzyle) ou DDZ (a,a-dimCthy1-3,sdimCthoxybenzyloxycarbonyle). La prCsence du groupe triCthoxysilyle permet la formation de monocouches auto-assemblCes. La libCration des groupements amines chimiquement rCactifs est accomplie par irradiation de la surface. Une mCthode Clectroanalytique a Ct C dCveloppCe et utilisCe pour suivre et optimiser les trois Ctapes de la mCthodologie se produisant i la surface : la formation de la monocouche, la photodCprotection et la fonctionnalisation subskquente des groupes amines libCrCs. De l'information quantitative sur I'efficacitC de 1'Ctape de dkprotection a Ct C obtenue par cette mCthode. I1 a Ct C dCcouvert que le groupe DDZ est supCrieur aux groupes protecteurs...

Novel Labile Protected Amine Terpolymers for the Preparation of Patterned Functionalized Surfaces: Synthesis and Characterization

“…Fodor et al successfully used low molar mass amino compounds protected by N ‐nitroveratryloxycarbonyl to create SAM films on a solid substrate which allowed after UV irradiation the selective growth of peptides 19. Jennane et al20 studied similarly labile protected amino group containing SAM layers investigating the optimization of the protecting group and the deprotection step.…”

Micropatterning of Titanium Dioxide on Self-Assembled Monolayers Using a Liquid-Phase Deposition Process

“…The ability to alter the chemical reactivity of the “R” pendant groups through exposure to UV light, − electron or ion − beams, or plasmas or low-energy electrons generated using proximal probes , represents an additional advantage in that it provides a means to create spatially well-defined reactivity templates in the organosiloxane SAM. Si−C bond cleavage predominates during exposure for many, ,,, although not all, , organosiloxane SAMs studied to date, leading to formation of reactivity templates comprised of separate regions of intact pendant “R” groups and surface silanol species. Such simple templates have proven effective for the fabrication of biosensors − and microelectronic circuitry …”

Polydiacetylene Single-Walled Carbon Nanotubes Nano-Hybrid for Cellular Imaging Applications

“…For micro-patterning as illustrated in Figure 5(a) self-assembled monolayer (SAM) techniques. 27 Secondly, FITC-avidin was immobilized by biotin-avidin interaction. Finally, biotin-EDA-PDA/SWCNTs was captured by unoccupied sites of avidin.…”