Surface with 3-Aminopropyltriethoxysilane

In many cases, silicon organic compounds are used as connecting links between a silica surface and a biomolecule. The most popular technique utilizes the modification of a hydroxy-functionalized surface with 3-aminopropyltriethoxysilane (APTES) [2] followed by crosslinking with glutaraldehyde (GA) (Fig. 1 A). 

The prominent goal of these studies was the detection of interactions between substrate and silyl esters with different organic groups R. The model substrates used include various kinds of silica, alumina, titania in addition to typical sandstones and silicon wafers. With respect to a contribution in the first conference report [3] one example may suffice here to demonstrate the procedure and the importance of the result obtained. The example concerns the treatment of a silicon wafer surface with 3-aminopropyltriethoxysilane (APTES) aimed at the detection of covalent bonding and possible interaction of the functional aminopropyl group with reactive surface centers. The method of choice is a... 

The specific functionalization of the unprotected silica surface with a trialkoxysilane derivative such as CH3Si(OCH3)3 is then carried out in a slightly basic water-ethanol suspension of the snowman-like particles. TEM images (Figure 1.29) of the resulting suspension of latex nanoparticles whose unmodified part was further functionalized with a second trialkoxysilane such as aminopropyltriethoxysilane and then... 

However, more interesting from an application point of view are silylation reactions which introduce new functions into the materials. These can be created either directly or in subsequent further steps after silylation. Most simple is the direct conversion of the silica to a basic material by reaction, for instance, with 3-aminopropyltriethoxysilane [17]. Also two-step processes have been employed to synthesize basic materials, where first chloropropyl groups are anchored to the surface with subsequent conversion of the chloro group into an amine. In order to remove the residual, unreacted silanol groups, a second silylation with hexamethyldisilazane can be used. Such materials were found to be reasonably active in different base-catalyzed reactions, such as Knoevenagel condensations and Michael additions. A survey of the catalyzed reactions and the types of modification used can be found in Ref. [5]. 

Another electrochemical domain to which XPS has made major contributions is surface modification (Chapter 14). Figure 17.3.7a contains data showing the effect of treating a glassy carbon surface with y-aminopropyltriethoxysilane to produce an amine functionalized carbon surface (99). The rise of the silicon and nitrogen peaks and the... 

Another interesting method for generating single-electron transistors is to prestructure the substrate surface, followed by deposition of the nanoparticles, and finally to place two or more metal electrodes across the nanoparticle chain. This method was described by Coskun et al. [67], who first spin-coated a cleaned silicon substrate with PMMA, and then structured the surface with EBL to define the desired patterns, treated the substrate vhth a aminopropyltriethoxysilane (APTES) solution. 

UV irradiation of H-terminated diamond covered with liquid films of an appropriate alkene [177] is also viable. The addition of aminosilane groups to the diamond surface is possible by reacting O-terminated diamond with 3-aminopropyltriethoxysilane (APTES). Carboxylation of the surface involves reacting an aminated surface with succinyl chloride and triethyl amine [178]. 

First, cores of silica nanoparticles are fabricated as described by Stober et alP in which tetraethyl orthosilicate is reduced in NH4OH in ethanol. Next, the silica surface is aminated by reaction with aminopropyltriethoxysilane in ethanol. Gold shells are then grown using the method of Duff et Briefly, small gold colloid (1-3 nm) is adsorbed onto the animated silica nanoparticle... 

Figures 13.15 and 13.16 show two examples that underline the flexibility and robustness of this technique for nanofabrication. Figure 13.15a shows the steps to build molecular architectures by combining top-down nanolithography and self-assembled methods. In this case, single molecules of ferritin have been deposited on silicon surfaces with an accuracy similar to the size of the molecules (r IO nm. First, the silicon surface is covered with a self-assembled monolayer of aminopropyltriethoxysilane (APTES), and then a region is locally oxidized with the atomic force microscope tip. The oxidation process also removes the monolayer under the tip. The nanostripe before the deposition of ferritin molecules is shown in Fig. 13.15b, while Fig. 13.15c shows a densely packed distribution of proteins on the nanostripe. The...

Figure 15.2 Schematics of the reaction between 3-aminopropyltriethoxysilane (APTES) and hydroxyl groups on the surface of ceramics. This method can be successfully applied to any surface with -OH functionalities.

Anchored amine materials can be prepared through a number of synthetic methodologies. Because of the potential importance of these materials to organic synthesis, a ninhydrin assay was developed as a rapid laboratory determination of available surface amines. The assay agreed well with expected values for aminopropyltriethoxysilane grafted onto commercial silica. The assay also distinguished between reactive amines and protonated or poisoned surface amines on co-condensed SBA-15 materials. 

CNTs offer an exciting possibility for developing ultrasensitive electrochemical biosensors because of their unique electrical properties and biocompatible nanostructures. Luong et al. have fabricated a glucose biosensor based on the immobilization of GOx on CNTs solubilized in 3-aminopropyltriethoxysilane (APTES). The as-prepared CNT-based biosensor using a carbon fiber has achieved a picoamperometric response current with the response time of less than 5 s and a detection limit of 5-10 pM [109], When Nation is used to solubilize CNTs and combine with platinum nanoparticles, it displays strong interactions with Pt nanoparticles to form a network that connects Pt nanoparticles to the electrode surface. The Pt-CNT nanohybrid-based glucose biosensor... 

Covalent binding of amino, carboxy, and nitro-substituted aminopropyltriethoxysilanes to oxidized silicon surfaces and their interaction with octadecanamine and octadecanoic acid studied by X-ray photoelectron spectroscopy and ellipsometry... 

Adhesion of polyimides to inorganic substrates is of great importance to the microelectronics industry [1, 2]. The polyimide films are deposited most often by spin coating the polyamic acid (PAA) usually from a TV-methylpyrrolidone (NMP) solution onto the substrate surface followed by thermal imidization at temperatures up to 400<>C. The most studied polyimide is the pyromellitic dianhydride-oxydianiline (PMDA-ODA), which exhibits excellent mechanical and dielectric properties, but not so good adhesion characteristics. The latter has been generally overcome by application of an adhesion promoter, such as y-aminopropyltriethoxysilane [3-7]. The reactions of APS (coated from water solution) with the silicon dioxide surface as well as with polyamic acid have been well characterized by Linde and Gleason [4] however, we do not have such detailed information available on APS interaction with other ceramic surfaces. 

The aminosilane coupling agent 3-aminopropyltriethoxysilane or y-amino-propyltriethoxy silane—also abbreviated as 3-APS, y-APS, APS or A1100 (Union Carbide)—is widely used to promote adhesion between polyimide thin films and mineral surfaces such as native-oxide silica, alumina and various glass ceramics [1, 2]. The structure of APS and the hydrolysis reaction sire shown in Fig. 1. Typically, dilute aqueous solutions of 0.1 vol% or approximately 0.080 wt % are employed to prime the mineral surface. The mechanism for the interaction of the bifunctional aminosilane with the mineral surface is the subject of much speculation, although it is conjectured by Linde and Gleason [3] that the amine end initially forms an electrostatic bond with surface hydroxyls. Subsequently, possibly as the result of elevated temperatures, the silanol end of the molecule proceeds to form a siloxane-like bond with the surface and the amine... 

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