Liquid Manipulation Lithography to Fabricate a Multifunctional Microarray of Organosilanes on an Oxide Surface under Ambient Conditions

Abstract

A novel method to produce a multifunctional microarray in which different types of self‐assembled monolayers (SAMs) are positioned on predefined surface sites on an oxide‐covered silicon substrate is described. To achieve this, a liquid‐transportation system called “liquid manipulation lithography” (LML) is developed. This system allows the delivery of different varieties of molecular inks, trialkoxysilanes, onto each predefined surface position of the given substrate even under ambient conditions. Under optimum conditions, the transferred trialkoxysilane inks first form one‐molecule‐thick microstructures at each surface position through the hydrolysis of the reactive silanes with surface water adsorbed on the substrate, followed by a condensation reaction. Three types of trialkoxysilanes with long alkyl‐chains, specifically triethoxysilylundecanal (TESUD), N‐(6‐aminohexyl)‐3‐aminopropyltrimethoxysilane (AHAPS), and octadecyltrimethoxysilane (OTS), are used as model molecular inks due to their high‐end group‐functionalities in biological and electronic applications. The precise positioning of the ink with sub‐micrometer edge resolution is performed by carefully controlling a femtoliter‐scale liquid‐injection micromanipulator under a microscope. To ensure that the prepared SAM microarray is available for parallel analysis of biomolecular interactions, the area‐selective immobilization of a protein molecule is explored. Successful observation of the area‐selective biomolecular attachment confirmed a high industrial potential for the method as a lithography‐free process for the miniaturization of a multifunctional SAM array on an oxide substrate.

Organometallic Chemistry on IV Semiconductors and Potential Applications

“…The magnitude of each surface potential contrast approximately corresponds to the ideal values. 12 This indicates the successful fabrication of the microarray, in which two different types of monolayers are positioned on each predefined surface site. Next, the potentiality of this microarray as single-molecule thick platform for protein array is examined using protein G, which is an immunoglobulin-binding protein.…”

“…This section describes our recent developed direct-writing method to produce monolayer microarray on OH-terminated Si and BDD. 12 For example, the use of BDD provides both transparency and conductivity for electrochemical parallel detection of specific biomolecular events. The lithography-free method starts with the transfer of different alkoxysilane inks to the predefined surface positions on a substrate under ambient conditions respectively, as shown in Figure 7a.…”

Monolayer Formation of Luminescent Germanium Nanoparticles on Silica Surface in Aqueous Buffer Solution

“…The SAM microarray was prepared by liquid manipulate lithography on the basis of our previous study. 20 In this study, two different kinds of SAM precursors, i.e., triethoxysilylundecanal (TESUD) and N -(6-aminohexyl)-3-aminopropyltrimethoxysilane (AHAPS) were used as molecular inks. These two different molecular inks, i.e., TESUD and AHAPS, were drawn into the glass syringe of a femtoliter-scale liquid-injection micromanipulator, and positioned on the predefined sites by careful control of the micromanipulator under a microscope, respectively.…”

Controlled organic/inorganic interface leading to the size-tunable luminescence from Si nanoparticles

“…For this purpose, we prepared a multifunctional SAM microarray by combining the LML method and two different alkoxysilane inks as demonstrated in our previous paper. 37) Specifically, two different molecular inks, i.e., TESUD and AHAPS, were positioned on the predefined sites by careful control of a femtoliter-scale liquid-injection micromanipulator under a microscope, respectively (see Fig. 8a).…”

“…37) Specifically, the direct-writing for creating SAM microarray was initiated by delivering neat alkoxysilane inks to predefined surface sites of SiO 2 /Si substrate. The precise positioning of the inks was achieved by a combination of a microinjection system (FemtoJet, eppendorf Co., Ltd.) and a micromanipulator (InjectMan NI2, eppendorf Co., Ltd.) with a femtochip, which was a glass capillary tube with an internal diameter of 500 nm, under optical microscopy observation.…”