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21.
Kamisetty NK Pack SP Nonogawa M Devarayapalli KC Kodaki T Makino K 《Analytical and bioanalytical chemistry》2006,386(6):1649-1655
Aminosilane-treated molecular layers on glass surfaces are frequently used as functional platforms for biosensor preparation.
All the amino groups present on the surface are not available in reactive forms, because surface amino groups interact with
remaining unreacted surface silanol groups. Such nonspecific interactions might reduce the efficiency of chemical immobilization
of biomolecules such as DNA, enzymes, antibodies, etc., in biosensor fabrication. To improve immobilization efficiency we
have used additional surface silanization with alkylsilane (capping) to convert the remaining silanol groups into Si–O–Si
linkages, thereby liberating the amino groups from nonspecific interaction with the silanol groups. We prepared different
types of capped amine surface and evaluated the effect of capping on immobilization efficiency by investigating the fluorescence
intensity of Cy3-NHS (N-hydroxysuccinimide) dye that reacted with amino groups. The results indicate that most of the capped amine surfaces resulted
in enhanced efficiency of immobilization of Cy3-NHS compared with the untreated control amine surface. We found a trend that
trialkoxysilanes had greater capping effects on immobilization efficiency than monoalkoxysilanes. It was also found that the
aliphatic chain of alkylsilane, which does not participate in the capping of the silanol, had an important function in enhancing
immobilization efficiency. These results would be useful for preparation of an amine-modified surface platform, with enhanced
immobilization efficiency, which is essential for developing many kinds of biosensors on a silica matrix.
Enhancement of amine funtionality by capping with alkylsilane 相似文献
22.
Venkatapuram Padmavathi Annaji Venkata Nagendra Mohan Konda Mahesh 《Journal of heterocyclic chemistry》2008,45(4):1131-1138
Novel bisheterocycles, 1,2,3‐selenadiazoles, thiadiazoles and 2H‐diazaphospholes in combination with oxadiazoles, thiadiazoles and triazoles were prepared from phenacylsulfonylacetic acid methyl ester. 相似文献
23.
Kamisetty NK Pack SP Nonogawa M Devarayapalli KC Watanabe S Kodaki T Makino K 《Analytical and bioanalytical chemistry》2007,387(6):2027-2035
Amine-modified oligodeoxynucleotides (AMO) are commonly used probe oligodeoxynucleotides for DNA microarray preparation. Two
methods are currently used for AMO preparation—use of amine phosphoramidites protected by acid-labile monomethoxytrityl (MMT)
groups or alkali-labile trifluoroacetyl (TFA) groups. Because conventional AMO preparation procedures have defects, for example
stringent acidic conditions are required for deprotection of MMT and hydrophobic purification cannot be used for TFA-protected
amino groups, conventional preparation of AMO is unlikely to result in the expected outcome. In this paper a method of AMO
synthesis using modified H-phosphonate chemistry is suggested. An aliphatic diamine is coupled with a phosphonate group forming
a phosphoramidate linkage to the last internucleotide phosphate of oligodeoxynucleotides. In this method dimethoxytrityl (DMT)
purification steps are used and stringent acid deprotection is not required to obtain the AMO. Although the method could lead
to formation of AMO diastereomers, melting-temperature and CD analysis showed for two AMO that DNA duplex formation was the
same as when normal oligodeoxynucleotides were used. Also, when these AMO were used as probes for DNA microarrays the immobilization
efficiency was similar to that for AMO probes prepared by conventional means using an amino-modifier unit. The hybridization
performance of these AMO was better than for those prepared conventionally. The procedures suggested would be useful for preparation
of efficient AMO for fabrication of DNA microarrays and DNA-based nanoparticle systems.
Nagendra Kumar Kamisetty and Seung Pil Pack have equally contributed to this work. 相似文献
24.
Venkatapuram Padmavathi Boreddy Chandra Obula Reddy Annaji Venkata Nagendra Mohan Adivireddy Padmaja 《Journal of heterocyclic chemistry》2007,44(2):459-462
Some bisheterocycles having pyrrole and oxazoline/thiazoline units were synthesized from Z‐styrylsulfonylacetic acid methyl esters using samarium chloride. 相似文献
25.
A facile process for the catalyst‐free and solvent‐free hydroboration of aromatic as well as heteroaromatic imines is reported. This atom‐economic methodology is scalable, compatible with sterically and electronically diverse imines, displaying excellent tolerance towards various functional groups, and works efficiently at ambient temperature in most of the cases, affording secondary amines in good to excellent yield after hydrolysis. 相似文献
26.
J.S. Yadav Sandip Sengupta Nagendra Nath Yadav D. Narasimha Chary Ahmad Alkhazim Al Ghamdi 《Tetrahedron letters》2012,53(44):5952-5954
(−)-Lardolure and (2R,4R,6R,8R)-2,4,6,8-tetramethylundecanoic acid have been synthesized via lipase catalyzed desymmetrization strategy to create two methyl chiral centers. Other key steps involved in the synthesis are Wittig reaction, Evan’s asymmetric alkylation, Grignard reaction, Pd-catalyzed isomerization of primary allylic alcohol to corresponding saturated aldehyde, and PhNO/proline catalyzed MacMillan α-hydroxylation. 相似文献
27.
Basi V. Subba Reddy Nagendra Nath Yadav Nikhil Srivastava Jhillu S. Yadav Balasubramanian Sridhar 《Helvetica chimica acta》2012,95(1):76-86
Ionic liquids were found to be a suitable reaction medium for 1,4‐dipolar cycloaddition reactions of an isoquinoline, an activated alkyne, and a 4‐oxo‐4H‐1‐benzopyran‐3‐carboxaldehyde at room temperature to afford [1]benzopyrano‐pyrido‐isoquinoline (=9aH,15H‐benzo[a][1]benzopyrano[2,3‐h]quinolizine) derivatives selectively in good yields. The ionic liquid can be recovered and recycled in further runs without loss of activity. 相似文献
28.
Rapid defunctionalization of carbonyl group to methylene with polymethylhydrosiloxane-B(C(6)F(5))(3)
The polymethylhydrosiloxane-B(C(6)F(5))(3) combination is found to be a versatile carbonyl defunctionalization system under mild and rapid conditions. For the first time, B(C(6)F(5))(3) has been used as a nonconventional Lewis acid catalyst to activate PMHS. Aromatic and aliphatic carbonyl compounds were effectively reduced to give the corresponding alkanes in high yields. 相似文献
29.
A new class of S-linked 1,3,4-oxadiazole-tethered Nα-protected peptidomimetics is designed and synthesized by a reaction of Nα-Z/Boc-protected 1,3,4-oxadiazole-2-thiol with α-bromo ester derived from amino acid. The protocol has also been employed for the synthesis of glycosylated amino acids and N,N′-orthogonally protected dipeptidomimetics bearing S-linked 1,3,4-oxadiazole mimetics as well. The intermediate 5-alkyl amino-1,3,4-oxadiazole-2-thiols have been isolated as stable compounds. Further, the chain extension at both N- and C-termini of N-protected S-linked 1,3,4-oxadiazole tethered dipeptidomimetics was also demonstrated. 相似文献
30.
P.V. Sri Ramya Srinivas Angapelly Chander Singh Digwal Upasana Yadav Bathini Nagendra Babu Ahmed Kamal 《Journal of Saudi Chemical Society》2018,22(1):90-100
A simple and efficient protocol has been demonstrated for the preparation of densely functionalized 3-aroylimidazo[1,2-a]pyridines from 2-aminopyridines and chalcones using RuCl3·H2O/I2 catalytic system. The advantages, such as low catalyst loading, broad substrate scope with respect to substitutions on aminopyridines as well as chalcones, stability of heterocycles such as thiophene under the reaction conditions, operationally simple procedure and higher yields makes this approach remarkable for synthetic applications. 相似文献