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51.
We herein present a compact disc (CD) microfluidic chip based hybridization assay for phenylketonuria (PKU) screening. This CD chip is composed of a polydimethylsiloxane (PDMS) top layer containing 12 DNA hybridization microchannels, and a glass bottom layer with hydrogel pad conjugated DNA oligonucleotides. Reciprocating flow was generated on the CD chip through a simple rotation-pause operation to facilitate rapid DNA hybridization. When rotated the CD chip, the sample solution was driven into the hybridization channel by centrifugal force. When stopped the CD chip, the sample plug was pulled backward through the channel by capillary force. The hybridization assay was firstly validated with control samples and was then used to analyze 30 clinical samples from pregnant women with suspected PKU fetus. The on-chip DNA hybridization was completed in 15 min with a sample consumption as low as 1.5μL, and the limit-of-detection (LOD) of DNA template was 0.7ng/μL. Among the 30 samples tested, V245V mutation was identified in 4 cases while R243Q mutation was detected in one case. Results of the hybridization assay were confirmed by DNA sequencing. This CD-chip based hybridization assay features short analysis time, simple operation and low cost, thus has the potential to serve as the tool for PKU screening. 相似文献
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54.
半导体荧光量子点因其独特的一元激发/多元发射、耐光漂白、发射波长可调等光学性质在细胞生物学研究、生物化学传感、药物筛选及示踪、环境监测等诸多领域都得到广泛的应用.本文简述了量子点的基本特性,重点介绍了近年来基于量子点的荧光特性及其与荧光共振能量转移、分子信标、荧光原位杂交等分析技术相结合而发展起来的一些新技术,以及基于QDs的阳极溶出伏安法和电化学发光在多组分分析方面的研究进展,最后就该研究领域现存的问题和将来的发展方向提出了拙见. 相似文献
55.
《Magnetic resonance in chemistry : MRC》2003,41(9):714-717
An NMR study of ketones 5–12 was undertaken to gain insight into the low electrophilicity of the carbonyl moiety of butenones 9–11. Initial IR studies on compounds 9–12 indicated that there is relatively strong double bond character (and hence low electrophilicity) in the carbonyl of saturated and unsaturated cyclobutyl ketones. The 13C chemical shifts confirm that the carbonyl moiety is highly conjugated with the fused benzene ring in 9, and with the olefinic linkage in 10 and 11. Partial positive charge is distributed away from the carbonyl carbon, which is also expected to lower the electrophilicity of the carbonyl carbon atoms of 9–11. One‐bond carbon–proton coupling constants (1JCH) depend directly on carbon hybridization. In the four‐membered ring ketones 9–12 the experimental values are larger than in cyclobutane, probably as a result of the additional strain of the extra trigonal centers in the ring. A similar trend is seen in the case of the olefinic CH in 10 and 11 (ca 175 Hz), for which the coupling constant is larger than for the corresponding carbon in cyclobutene. 1JCC values between the ring carbon atoms of the cyclobutenones are some 20% lower than in the models—a bigger difference than in cyclobutanes, again indicative of the increased ring strain. The very low 42.4 Hz coupling between C‐1 and C‐2 in 9 might well indicate a measure of bond localization. 2JCC and 3JCC values are also discussed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
56.
According to empirical electron theory of solids and molecules (EET), an equation for calculating the cohesive energy of actinide
metals is given, the cohesive energy of 9 actinide metals with known crystal structure is calculated, which is identical with
the experimental values on the whole, and the cohesive energy of 6 actinide metals with unknown crystal structure is forecast. 相似文献
57.
Chinese Spring Tal kr phlb plants were developed by hybridizing Tal common wheat and Chinese Spring phlb mutant and backcrosses. When Chinese Spring Tal kr phlb plants were crossed with some wild species of Triticeae, much more seeds of wide hybridization can be obtained without artificial emasculation and pollination because of the existence of Tat and kr genes. The homoeologous chromosomes between common wheat and the wild species of Triticeae can also pair and exhibit cross-over in the hybrid F1 plants because of the existence of the phlb gene. So that more alien desirable genes can be transferred to common wheat rapidly. Therefore, Chinese Spring Tal kr phlb plants become a powerful tool for wide hybridization and transferring alien desirable genes to common wheat. 相似文献
58.
A novel protocol for the synthesis of dye-encapsulating liposomes tagged with DNA oligonucleotides at their outer surface
was developed. These liposomes were optimized for use as signal enhancement agents in lateral-flow sandwich-hybridization
assays for the detection of single-stranded RNA and DNA sequences. Liposomes were synthesized using the reverse-phase evaporation
method and tagged with oligonucleotides by adding cholesteryl-modified DNA probes to the initial lipid mixture. This resulted
in a greatly simplified protocol that provided excellent control of the probe coverage on the liposomes and cut the preparation
time from 16 hours to just 6 hours. Liposomes were prepared using probe concentrations ranging from 0.00077 to 0.152 mol%
of the total lipid, several hydrophobic and polyethylene glycol-based spacers between the cholesteryl anchor and the probe,
and liposome diameters ranging from 208 nm to 365 nm. The liposomes were characterized by dynamic light scattering, visible
spectroscopy, and fluorescence spectroscopy. Their signal enhancement functionality was compared by using them in lateral-flow
optical biosensors for the detection of single-stranded DNA sequences. In these assays, an optimal reporter probe concentration
of 0.013 mol%, liposome diameter of 315 nm, and liposome optical density of 0.4–0.6 at 532 nm were found. The spacer length
between the cholesteryl anchor and the probe showed no significant effect on the signals in the lateral-flow assays. The results
presented here provide important data for the general use of liposomes as labels in analytical assays, with specific emphasis
on nucleic acid detection via lateral flow assays. 相似文献
59.
Nobuko Ohmido Kiichi Fukui Toshiro Kinoshita 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2010,86(2):103-116
Fluorescence in situ hybridization (FISH) is an effective method for the physical mapping of genes and repetitive DNA sequences on chromosomes. Physical mapping of unique nucleotide sequences on specific rice chromosome regions was performed using a combination of chromosome identification and highly sensitive FISH. Increases in the detection sensitivity of smaller DNA sequences and improvements in spatial resolution have ushered in a new phase in FISH technology. Thus, it is now possible to perform in situ hybridization on somatic chromosomes, pachytene chromosomes, and even on extended DNA fibers (EDFs). Pachytene-FISH allows the integration of genetic linkage maps and quantitative chromosome maps. Visualization methods using FISH can reveal the spatial organization of the centromere, heterochromatin/euchromatin, and the terminal structures of rice chromosomes. Furthermore, EDF-FISH and the DNA combing technique can resolve a spatial distance of 1 kb between adjacent DNA sequences, and the detection of even a 300-bp target is now feasible. The copy numbers of various repetitive sequences and the sizes of various DNA molecules were quantitatively measured using the molecular combing technique. This review describes the significance of these advances in molecular cytology in rice and discusses future applications in plant studies using visualization techniques. 相似文献
60.
Elodie Decuypere Anastasia Lepikhina Franois Halloy Jonathan Hall 《Helvetica chimica acta》2019,102(12)
Structural modification at the 2′‐O‐position of riboses in oligonucleotide therapeutics is of critical importance for their use as drugs. To date, the methoxyethyl (MOE) substituent is the most important and features in dozens of antisense oligonucleotides that have been tested in clinical trials. Yet, the search for new improved modifications continues in a quest for increased oligonucleotide potency, improved transport in vivo and favorable metabolism. Recently, we described how the conjugation of spermine groups to pyrimidines in oligonucleotides vastly increases their affinity for complementary RNAs through accelerated binding kinetics. Here we describe how spermines can be linked to the exocyclic amino groups of cytidines in MOE‐oligonucleotides employing a straightforward ‘convertible nucleoside approach’ during solid phase synthesis. Singly‐ or doubly‐modified oligonucleotides show greatly enhanced affinity for complementary RNA, with potential for a new generation of MOE‐based oligonucleotide drugs. 相似文献