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Mesoscopic organosilicas were synthesized with bis(triethoxysilyl)ethane (BTSE) and cetyltrimethylammonium chloride (CTAC) under basic conditions. Further functionalization was achieved by co-condensation with trialkoxyorganosilanes. Surfactant extraction produced periodic mesoporous organosilicas (PMO's) functionalized with the respective organosilane pendent groups. Organosilanes used in this study include: 3-aminopropyltrimethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 2-(trimethoxysilylethyl)pyridine, n-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, phenethyltrimethoxysilane, and benzyltriethoxysilane. These materials have been characterized by nitrogen gas adsorption, powder X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), elemental analysis (EA), and high-resolution thermogravimetric analysis (TGA). The effect of organosilane incorporation on the porous structure of these materials is examined.

In order to study the effect of organic surface chemistry on calcite nucleation, attachment, and growth, calcium carbonate was precipitated in the presence of various ultrathin-film organosilane-modified silicon wafers. The chemistry of the aminosilane surfaces was systematically changed by the coupling of various acidic molecules, without creating a geometric lattice of acidic functional groups. Optical microscopy, scanning electron microscopy with image analysis, and X-ray scattering were employed to characterize crystallite density and orientation normal to the surface. Calcite grown on amino-modified surfaces was produced with the equilibrium rhombohedral habit and had the 〈104〉 orientation. Surfaces of the silicon oxide, carboxylate, iminodiacetate, or phosphoramidate tended to favor the orientation of surface crystals along 〈001〉 or near the 〈001〉 axes of the crystal. Primarily this is a result of the affinity of the surface for cations, but functional-group-mediated ion ordering and/or stereochemical matching is also suggested by the much greater amount of crystal nucleation on the long-chain carboxylates when compared to shortchain carboxylates. Coupling of nitrilotriacetic acid (NTA) favored appearance of 〈110〉, 〈113〉, and 〈116〉 oriented crystals when compared to the other acid surfaces. Growth of calcite with relatively larger {110} faces was observed when the microcrystals were synthesized in the presence of freely soluble NTA. Appearance of these faces is a result of a relatively suppressed growth rate due to face-specific adsorption on the growing crystallites. Similarly, the enhancement of specific crystal surface binding by the substrate bound NTA is probably the mechanism influencing orientation of surface microcrystals. Two common structural features of the {110}, {113}, and {116} faces are the tilt of the carbonate plane at large angles from the face and the same angle of rotation of the carbonates about their 3-fold symmetry axes. That angle may enhance the ability of two NTA carboxylates to simultaneously occupy carbonate sites of these calcite faces. The fact that crystallite density and orientation are influenced by submonolayers of functional groups attests to the importance of electrostatic and stereochemical recognition of certain crystal faces even without matching of the geometric lattice.

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Micropatterned arrays of active proteins are vital to the next generation of high-throughput multiplexed biosensors and advanced medical diagnostics. We have developed a simple method for fabricating antibody arrays using a micromolded hydrogel “stamper” and an aminosilylated receiving surface. The stamping procedure permits direct protein deposition and micropatterning while avoiding cross-contamination of separate patterned regions. Three different antibodies were stamped in adjacent arrays of 50−80 μm circular areas with retention of activity. 125I labeling and atomic force microscopy studies showed that the stamper deposited protein as a submonolayer. The fluorescent signal-to-background ratio of labeled bound antigen was greater than 25:1.