Biomedical subjects

Nagendra Kumar Kamisetty

Publications and source records attributed to Nagendra Kumar Kamisetty.

6 recordsLinked to original sources

PubMed2006

Development of an efficient amine-functionalized glass platform by additional silanization treatment with alkylsilane.

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.

Alkylation↗

PubMed2006

Structural property and enzymatic response of oxanine in DNA strands.

Oxanine (Oxa, O), one of the major products generated from guanine (Gua) by nitrosative oxidation has been expected as mutagenic lesion involved in NO- or HNO(2) -induced genotoxicity. Here, to elucidate the biological meaning of Oxa in DNA strands, several kinds of Oxa-containing oligodeoxynucleotides (Oxa-ODNs) were synthesized and applied to biophysical and biochemical characterization. CD and NMR analyses revealed that the conformations of all the Oxa-containing duplexes are basically B-type without causing any severe distortion in the whole DNA structure. It was also determined that restriction endonucleases recognize and cleave the specific base-sequence even when Gua was substituted by Oxa in the sequence. When Oxa-ODN was testified as substrates for other DNA-relevant enzymes, the enzymatic functions were not largely affected by Oxa.

Alkaline Phosphatase↗

PubMed2006

Synthesis and application of new amine-modified oligonucleotides using H-phosphonate chemistry.

Oligodeoxynucleotide probes tethered with amine linkers are commonly used for development of DNA based biosensor tools for studying gene expression and biological assays. However, the current preparation methods for synthesizing amine tethered probes often show defects during acid deprotection and during hydrophobic purification with the amine linker protecting groups. Here, we developed a prospective preparation method of using modified H-phosphonate chemistry to prepare amine tethered oligonucleotide probes. The present developed method will be helpful for preparing efficient amine tethered oligodeoxynucleotide probes that can be used in DNA biosensor applications.

Amines↗

PubMed2006

Development of DNA-arrayed column for sensitive and selective analysis of DNA.

Quantitative separation of target DNA molecules was performed by DNA-arrayed silica capillary column on the basis of base pairing interaction of nucleic acids. We prepared DNA-arrayed silica capillary column by conjugating 5'-amniohexyl oligonucleotide (probe) on inner surface of the capillary column pre-treated with 3-aminopropyltriethoxysilane (APS) and disuccinimidyl glutarate (DSG) cross-linker. Sufficient resolution was observed by controlling of target-DNAs concentration, salt gradients, and temperature gradients. Finally, we succeeded to separate two different DNA targets even with same melting temperature according to their own concentrations. These results would be useful for developing quantitative analysis of cDNA, which is related to mRNA levels in biological sample.

Chromatography, Affinity↗

PubMed2005

Fabrication of efficient DNA microarray by additional surface modification and functional probe design.

DNA microarray, which exploits the preferential binding of complementary single stranded nucleic acids, is a powerful tool for obtaining high-throughput characterization of gene expression. Although this system is evolving rapidly, low-reproducibility of hybridization data is a major drawback to be overcome. Here, we developed additional surface modification step to reduce the hydrolysis of silyl ether bond between glass surface and linker molecule. In addition, we designed functional DNA probe for reducing the chemical treatments of glass surface. These surface/probe modifications will be helpful in fabricating more efficient DNA microarray system.

DNA Probes↗

PubMed2005

Biophysical and biochemical properties of oxanine-containing oligodeoxynucleotide.

Since oxanine (Oxa) was found as one of the major products from nitrosative oxidation of guanine, Oxa has been expected as mutagenic lesion related to NO-induced DNA damage. Here, to elucidate the mutagenic significance of Oxa in vitro, several Oxa-containing oligodeoxynucleotides (Oxa-ODNs) were synthesized and subjected to biophysical and biochemical characterization. Oxa-ODNs were analyzed in terms of their duplex stabilities and DNA polymerase responses. These results will be helpful in understanding the genotoxic pattern induced by Oxa.

DNA Polymerase I↗