Mercaptoundecanoic acid

Ester-thioester copolymers were enzymatically synthesized (Scheme 7). ° The lipase CA-catalyzed copolymerization of e-caprolactone with 11-mercaptoundecanoic acid or 3-mercaptopropionic acid under reduced pressure produced the polymer with molecular weight higher than 2 x 10". The thioester unit of the resulting polymer was lower than the feed ratio. The transesterification between poly(8-caprolactone) and 11-mercaptoundecanoic acid or 3-mercaptopropionic acid also took place by lipase CA catalyst. Recently, aliphatic polythioesters were synthesized by lipase CA-catalyzed polycondensation of diesters with 1,6-hexanedithiol. ... 

Mercaptohexanoic acid 8-Mercaptooctanoic acid 11-Mercaptoundecanoic acid 16-Mercaptohexadecanoic acid... 

Veiy recently it was disclosed, that the water-soluble dinuclear complex obtained in the reaction of [ RhCl(COD) 2] and 11-mercaptoundecanoic acid catalyzed the aqueous/organic biphasic hydroformylation of styrene and various arene-substituted styrenes with good activity and useful selectivity to the branched aldehydes (Scheme 4.6) [82], Below pH 4 the acid form of the complex [ Rh(p-S(CH2)ioC02H)(COD) 2] precipitated virtually quantitatively but could be redissolved in water on addition of base. Importantly, higher olefins could also be hydroformylated by this catalyst (for 1-octene TOP = 17.5 h at 55 °C, 35 bar syngas, n/i = 1.0). 

CALB-catalyzed copolymerization of CL with 11-mercaptoundecanoic acid (1IMU) leads to the formation of poly(ester-c6>-thioester)s having a Mn of 13.7 kDa (PDI 1.6) after precipitation [30] (Fig. 11). The amount of incorporated IIMU (8.7mol%) was slightly less than the feed ratio (10mol%). Similar results were obtained when using 3-mercaptopropionic acid (3MP) as a comonomer (Mn 14.3 kDa, PDI 1.4). CALB-catalyzed transesterification of pCL with either 1 IMU or 3MP resulted in similar H-NMR and C-NMR spectra as the direct copolymerization of the two monomers, showing that continuous transesterification plays an important role in the microstructure of the polymer [30]. 

In the voltammogram of Au(lll) modified with binary SAM of 1-undecanethiol and 11-mercaptoundecanoic acid, only one reductive desorption peak was formed for any value of mixing ratio of both thiols [139]. Such a response suggests that both thiols are well mixed in the SAM. 

MIP films, applied to a QCM transducer, have been employed for chiral recognition of the R- and 5-propranolol enantiomers [107]. MIP films were prepared for that purpose by surface grafted photo-radical polymerization. First, a monolayer of 11-mercaptoundecanoic acid was self-assembled on a gold electrode of the quartz resonator. Then, a 2,2 -azobis(2-amidinopropane) hydrochloride initiator (AAPH), was attached to this monolayer. Subsequently, this surface-modified resonator was immersed in an ACN solution containing the MAA functional monomer, enantiomer template and trimethylolpropane trimethacrylate (TRIM) cross-linker. Next, the solution was irradiated with UV light for photopolymerization. The resulting MIP-coated resonator was used for enantioselective determination of the propranolol enantiomers under the batch [107] conditions and the FIA [107] conditions with an aqueous-ACN mixed solvent solution as the carrier. The MIP-QCM chemosensor was enantioselective to 5-propranolol at concentrations exceeding 0.38 mM [107]. 

In this part we will describe recent achievements in the development of biosensors based on DNA/RNA aptamers. These biosensors are usually prepared by immobilization of aptamer onto a solid support by various methods using chemisorption (aptamer is modified by thiol group) or by avidin-biotin technology (aptamer is modified by biotin) or by covalent attachment of amino group-labeled aptamer to a surface of self-assembly monolayer of 11-mercaptoundecanoic acid (11-MUA). Apart from the method of aptamer immobilization, the biosensors differ in the signal generation. To date, most extensively studied were the biosensors based on optical methods (fluorescence, SPR) and acoustic sensors based mostly on thickness shear mode (TSM) method. However, recently several investigators reported electrochemical sensors based on enzyme-labeled aptamers, electrochemical indicators and impedance spectroscopy methods of detection. 

Fig. 11 Laterally gold structured silicon wafer to control the spatial adsorption of PVFA-co-PVAm (a) photograph of the gold structured silicon wafer (genuine size of the gold islands 45 pm by 45 pm), (b) spatially resolved XPS image of the lateral gold layer (the Au 4f peak is depicted in black whilst the peaks of O 1 s and Si 2p are pale), (c) spatially resolved XPS image of 11-mercaptoundecanoic acid adsorbed on the laterally structured gold layer (the S 2p peak is depicted in white whilst Si 2p is dark)...

MUA (11-mercaptoundecanoic acid), Sigma-Aldrich (Stein-heim, Germany). 

Iwata et al. [120] used Novozym 435 to catalyze copolymerizations of e-CL with 11-mercaptoundecanoic acid (11MU) and 3-mercaptopropionic acid (3MP). The same authors also demonstrated that Novozym 435 catalyzed transesterifications between poly( -CL) and 11-mercaptoundecanoic acid or 3-mercaptopropionic acid in o-xylene. 

Characterization of Self Assembled Monolayer Formation of 11-Mercaptoundecanoic Acid on Gold Surfaces... 

SAM Formation. SAMs of 11-MUA were prepared ex situ in 1-3 mM ethanolic solution of 11-mercaptoundecanoic acid, which was purchased at Sigma Aldrich. Two different substrates were used Au(lll)/mica and recrystallized gold foils. Typically, substrates are cleaned in piranha solution. This procedure was not possible for Au( 11 l)/mica, because it led to a separation of the gold layer from the mica substrate. Therefore, both substrates were cleaned in a UHV chamber by Ar+ -sputtering, followed by short annealing at 800 K to get a smooth surface. After removal from the vacuum chamber, it was immediately immersed into the solution. Typically samples remained for 48 h in the solution. After removal out of solution, the samples were rinsed with ethanol and dried with C02 - spray. 

Duan et al. used a monolayer of thioctic acid to covalently immobihse monoclonal antibodies to a gold electrode while performing amperometric analysis [28]. Frey et al. demonstrated potential biosensor application of this immobilisation method by binding polylysine to gold surface plasmon resonance (SPR) electrodes via a SAM of 11-mercaptoundecanoic acid [29]. 

An assay for diagnosing type I diabetes mellitus based on the detection of anti-glutamic acid decarboxylase (GAD) antibodies in buffer by a Biacore 2000, is presented in [47,48]. Biotinylated GAD was immobihzed on a streptavidin-coated surface. The effect of mixed SAM composition (differing in ratios of hydroxyl- and carboxyl-terminated alkanethiols) on the sensitivity of the sensor was investigated. On SPR sensor chips prepared with the optimized SAM composition (10 1 ratio of 3-mercaptopropanol to 11-mercaptoundecanoic acid), a concentration of anti-GAD as low as... 

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