Self-assembled silane compound

Stabilization of a lipid membrane onto a solid support by covalent attachment also provides the physical stability necessary for the development of practical sensors. An oriented membrane can be prepared by allowing self-assembly of individual amphiphilic molecules onto a solid surface through either the reaction of terminal silane moieties with a hydroxylated surface to form a silyl ether [33,34], or by the reaction of sulfur-terminated compounds (alkylthiols or disulfides) with gold surfaces [35,36]. A variety of species, both with and without polar head groups, have been deposited onto surfaces such as glass, quartz, silicon, and gold [37-39]. These include phospholipids, fatty acids, and fatty amines which were synthetically altered so as to contain either a silyl chloride or a thiol moiety at the terminus of the acyl chain [40]. Both monolayers... 

A new family of polysilsesquioxane colloids was synthesized by hydrolytic condensation of different functional amphiphilic silanes without any additional surfactants [58-60]. To choose a suitable monosubstituted silane, we looked for the combination of a functional group, which would be able to interact with metal compounds, and a hydrophobic part, which would self-assemble in an aqueous medium. We expected that a sol-gel reaction of such a precursor in water would yield multifunctional materials with internal ordering if the hydrophobic tail is sufficiently long. In this way, polysilsesquioxane colloids... 

Composites of PANI-NFs, synthesized using a rapid mixing method, with amines have recently been presented as novel materials for phosgene detection [472]. Chemiresistor sensors with nanofibrous PANI films as a sensitive layer, prepared by chemical oxidative polymerization of aniline on Si substrates, which were surface-modified by amino-silane self-assembled monolayers, showed sensitivity to very low concentration (0.5 ppm) of ammonia gas [297]. Ultrafast sensor responses to ammonia gas of the dispersed PANI-CSA nanorods [303] and patterned PANI nanobowl monolayers containing Au nanoparticles [473] have recently been demonstrated. The gas response of the PANI-NTs to a series of chemical vapors such as ammonia, hydrazine, and triethylamine was studied [319,323]. The results indicated that the PANI-NTs show superior performance as chemical sensors. Electrospun isolated PANI-CSA nanofiber sensors of various aliphatic alcohol vapors have been proven to be comparable to or faster than those prepared from PANI-NF mats [474]. An electrochemical method for the detection of ultratrace amount of 2,4,6-trinitrotoluene with synthetic copolypeptide-doped PANI-NFs has recently been reported [475]. PANI-NFs, prepared through the in situ oxidative polymerization method, were used for the detection of aromatic organic compounds [476]. 

An interesting example of a template polymerization was provided by Wu et al. [146]. Surfaces of Si02/Si substrates were first modified with a silane compound bearing pendant aniline groups via molecular self-assembly. This modified surface was then contacted with additional aniline monomer in the presence of the oxidant ammonium peroxydisulfate. The resulting CP films were claimed to be highly ordered with good substrate adhesion and conductivities for 1 /tm thick films were found to be 0.5 S/cm. 

Chemicals and solvents, reagent grade or better, were used as received (Alfa, Aldrich, or Fisher). Prior to monolayer self assembly, SAW devices were silanized using ClSi(CH3)3 (Petrarch) to prevent interactions between polar compounds (particularly the organophosphonates) and the quartz substrate from complicating interpretation of the response. SAMs of mercaptoundecanoic acid (MUA, HS(CH2)iqCOOH Aldrich) were produced by soaking Au-coated SAW devices in a dilute solution of the thiol in ethanol overnight... 

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