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Vilaivan C.,Organic Synthesis Research Unit | Srisuwannaket C.,King Mongkuts University of Technology Thonburi | Ananthanawat C.,Organic Synthesis Research Unit | Suparpprom C.,Naresuan University | And 4 more authors.
Artificial DNA: PNA and XNA | Year: 2011

We describe herein a new conformationally constrained analog of PNA carrying an alternating α/β amino acid backbone consisting of (2′R,4′R)-nucleobase-subtituted proline and (1S,2S)-2-aminocyclopentanecarboxylic acid (acpcPNA). The acpcPNA has been synthesized and evaluated for DNA, RNA and self-pairing properties by thermal denaturation experiments. It can form antiparallel hybrids with complementary DNA with high affinity and sequence specificity. Unlike other PNA systems, the thermal stability of acpcPNA·DNA hybrid is largely independent of G+C contents, and is generally higher than that of acpcPNA·RNA hybrid with the same sequence. Thermodynamic parameters analysis suggest that the A·T base pairs in the acpcPNA·DNA hybrids are enthalpically stabilized over G·C pairs. The acpcPNA also shows a hitherto unreported behavior, namely the inability to form self-pairing hybrids. These unusual properties should make the new acpcPNA a potentially useful candidate for various applications including microarray probes and antigene agents. © 2011 Landes Bioscience. Source

Ananthanawat C.,Chulalongkorn University | Vilaivan T.,Organic Synthesis Research Unit | Hoven V.P.,Organic Synthesis Research Unit | Su X.,Institute of Materials Research and Engineering of Singapore
Biosensors and Bioelectronics | Year: 2010

Pyrrolidinyl peptide nucleic acid bearing a d-prolyl-2-aminocyclopentanecarboxylic acid backbone (acpcPNA) has been evaluated as a new sensing probe for detection of DNA hybridization. In this study, the biotinylated acpcPNA was immobilized on surface plasmon resonance (SPR) sensor chips via biotin-streptavidin interactions for solid-phase DNA hybridization. A critical comparison between acpcPNA, DNA and conventional peptide nucleic acid (aegPNA) probes of the same sequence was made by means of SPR on various important aspects. These include the effect of ionic strength on hybridization efficiency, the specificity to detect the mismatch(es) in target DNAs, the direction of binding (parallel or antiparallel) to target DNAs, and the effect of target DNA concentration on hybridization efficiency. Results indicated that the immobilized acpcPNA probe possesses distinct hybridization properties relative to aegPNA (and/or DNA) counterparts, including a higher single-base mismatch sensitivity, antiparallel selectivity and low ionic strength dependence of target hybridization. These properties substantiate the acpcPNA applicability as sensor probes for clinical and diagnostic applications. With a proper selection of regeneration conditions (10 mM NaOH, 2 min exposure), the sensor can be reused for multiple cycles of hybridization with as little as 1.3% loss in hybridization activity per regeneration cycle. © 2009 Elsevier B.V. All rights reserved. Source

Pisuchpen T.,Organic Synthesis Research Unit | Chaim-Ngoen N.,Program in Petrochemistry and Polymer Science | Chaim-Ngoen N.,China National Petroleum Corporation | Intasanta N.,Chulalongkorn University | And 3 more authors.
Langmuir | Year: 2011

Electrospinning and silanization were synergistically employed to fabricate poly(vinyl alcohol) (PVA) and PVA/silica mixtures into flexible and chemically modifiable nanostructured surfaces with varying degrees of hydrophobicity and water adhesion. Surfaces possessing the greatest advancing water contact angle yet exhibiting a high level of water adhesion (θA/ θR ≈ 168°/0°) were achieved by the reaction of PVA fiber mats with multiple cycles of SiCl4/H2O treatment, followed by silanization with (1H,1H,2H,2H-perfluorooctyl)trichlorosilane. It is postulated that the strong pinning effect and hence the water adhesion originated from the collapse of the underlying fibrous structures and the removal of air pockets. The addition of silica to the PVA matrix improved the rigidity and thus prevented the fibers from collapsing, allowing air to remain trapped within the fibrous structure and giving the surface greater water repellency. Throughout the investigation, the three wetting models-Wenzel's, Cassie-Baxter's, and the Cassie-impregnating-were regularly referred to as a conceptual framework. The hydrophobic surface that exhibited strong water adhesion, or the so-called "Petal effect", was elucidated in correlation with the fibrous structure of the film, as reviewed by microscopic analysis. In summary, electrospinning as a facile and cost-effective method provides promising opportunities for investigating the mechanistic character of nanowetting, nanoprinting, and nanocoating where the precise control of the dynamical three-phase contact line is of paramount importance. © 2011 American Chemical Society. Source

Punthasee P.,Organic Synthesis Research Unit | Vanitcha A.,Organic Synthesis Research Unit | Wacharasindhu S.,Organic Synthesis Research Unit
Tetrahedron Letters | Year: 2010

A new approach to synthesize 3-alkylquinazolin-4-ones is developed. Treatment of quinazolin-4-ones with Mukaiyama's reagent, a base and a primary amine nucleophile results in the formation of 3-alkylquinazolin-4-ones in moderate to good yields under mild conditions. Using this methodology, a one-step synthesis of the natural alkaloid, echinozolinone, is accomplished. © 2010 Elsevier Ltd. All rights reserved. Source

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