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1.
Two protocols for functionalization of glass supports with hexaethylene glycol (HEG)-linked oligonucleotides were developed.
The first method (standard amidite protocol) made use of the 2-cyanoethyl-phosphoramidite derivative of 4,4′-dimethoxytrityl-protected
HEG. This was first coupled to the support by standard solid-phase phosphoramidite chemistry followed by extension with a
thymidylic acid icosanucleotide. Stepwise addition of the linker phosphoramidite graduated at 1% (relative to the total sites
available) perstep at 50°C resulted in an optimal yield of immobilized oligonucleotides at a density of 2.24 × 1010 strands/mm2. This observed loading maximum lies well below the theoretical maximum loading owing to nonspecific adsorption of HEG on
the glass and subsequent blocking of reactive sites. Surface loadings as high as 3.73 × 1010/mm2 and of excellent sequence quality were achieved with a reverse amidite protocol. The support was first modified into a 2-cyanoethyl-N,N-diisopropylphosphoramidite analog followed by coupling with 4,4′-dimethoxytrityl-protected HEG. This protocol is conveniently
available when using a conventional DNA synthesizer. The reverse amidite protocol allowed for control of the surface loading
at values suitable for subsequent analytical applications that make use of immobilized oligonucleotides as probes for selective
hybridization of sample nucleic acids of unknown sequence and concentration. 相似文献
2.
在前文工作的基础上,结合MNDO/EHMO分子轨道方法和自然杂化轨道方法,具体计算了CC键和CP键的核自旋偶合常数.计算结果表明,1JCC和1JCP主要由成键原子的轨道杂化作用和键极性这两种结构因素所决定.为从简单价键理论角度解释和计算1JCC和1JCP值提供了简便直观的方法. 相似文献
3.
P. Wust W. von Oertzen H. Ossenbrink H. Lettau H.G. Bohlen W. Saathof K. Wannebo C.A. Wiedner 《Physics letters. [Part B]》1979,80(3):208-211
High resolution for the 27Al(16O, 15N)28Si reaction were measured with a Q3D magnetic spectrometer. The broadened line shape of the (6.33 MeV) state after γ-decay in flight was analysed. The m-state population of this state was deduced taking the E2/M1 mixing ratio of δ = +0.1 into account. The connection between spin alignment and the dynamics of the transfer process is discussed. 相似文献
4.
Watterson JH Piunno PA Wust CC Raha S Krull UJ 《Fresenius' Journal of Analytical Chemistry》2001,369(7-8):601-608
The immobilization of oligonucleotides to solid surfaces can provide a platform of chemistry that is suitable for the development of biosensor and microarray technologies. Experiments were performed using a fiber optic nucleic acid biosensor based on total internal reflection fluorescence to examine the effects of the presence of non-complementary DNA on the detection of hybridization of complementary target DNA. The work has focused on the rates and extent of hybridization in the presence and absence of non-selective adsorption using fluorescein-labeled DNA. A stop-flow system of 137 microL volume permitted rapid introduction and mixing of each sample. Response times measured were on the order of seconds to minutes. Non-selective adsorption of non-complementary oligonucleotides (ncDNA) was found to occur at a significantly faster rate than hybridization of complementary oligomers (cDNA) in all cases. The presence of ncDNA oligonucleotides did not inhibit selective interactions between immobilized DNA and cDNA in solution. The presence of high concentrations of non-complementary genomic DNA had little effect on the extent of hybridization of complementary oligonucleotides, but actually reduced the response times of sensors to cDNA oligonucleotides. 相似文献
5.
赵乃良 《高校应用数学学报(A辑)》1996,(1):91-96
Nira Dyn等提出的四点插值法是一种典型的自由曲线离散造型方法,但该方法不能控制插值点的切向。本文利用薄板样很可能 量的极小化原理给出了具有切向控制的四点分插值条件。用户可以方便地交互控制任一插值点的切向,使得四点插值法更为有效和实用。 相似文献
6.
Influences of non-selective interactions of nucleic acids on response rates of nucleic acid fiber optic biosensors 总被引:1,自引:0,他引:1
James H. Watterson Paul A. E. Piunno Christopher C. Wust Sandeep Raha U. J. Krull 《Analytical and bioanalytical chemistry》2001,369(7-8):601-608
The immobilization of oligonucleotides to solid surfaces can provide a platform of chemistry that is suitable for the development
of biosensor and microarray technologies. Experiments were performed using a fiber optic nucleic acid biosensor based on total
internal reflection fluorescence to examine the effects of the presence of non-complementary DNA on the detection of hybridization
of complementary target DNA. The work has focused on the rates and extent of hybridization in the presence and absence of
non-selective adsorption using fluorescein-labeled DNA. A stop-flow system of 137 μL volume permitted rapid introduction and
mixing of each sample. Response times measured were on the order of seconds to minutes. Non-selective adsorption of non-complementary
oligonucleotides (ncDNA) was found to occur at a significantly faster rate than hybridization of complementary oligomers (cDNA)
in all cases. The presence of ncDNA oligonucleotides did not inhibit selective interactions between immobilized DNA and cDNA
in solution. The presence of high concentrations of non-complementary genomic DNA had little effect on the extent of hybridization
of complementary oligonucleotides, but actually reduced the response times of sensors to cDNA oligonucleotides.
Received: 26 September 2000 / Revised: 24 November 2000 / Accepted: 30 November 2000 相似文献
7.
P. Wust W. von Oertzen H. Ossenbrink H. Lettau H. G. Bohlen W. Saathoff C. A. Wiedner 《Zeitschrift für Physik A Hadrons and Nuclei》1979,291(2):151-161
The spin alignment of the15N 3 2/* (6.33 MeV) state was measured in the88Sr(16O,15N)89Y reaction atE L =96 MeV using theγ-recoil method. Angular distributions of excited states in15N and89Y were measured with high accuracy. The analysis in terms of DWBA shows that the spin alignment is correctly described by the usual reaction models. The polarisation of the outgoing15N1/2(GS) and15N 3 2/* (6.33 MeV) is discussed. It is shown that cross section differences for transitions to final states with different configurations are sensitive to a spin-orbit potential of15N. The strength and sign of the spin-orbit potential for15N is determined. 相似文献
8.
H. G. Bohlen W. von Oertzen P. Wust 《Zeitschrift für Physik A Hadrons and Nuclei》1979,292(1):105-106
The spin alignment of the12C2 + state in inelastic scattering of12c on64zn at EL=65 MeV has been measured using the γ-recoil-in-flight method. Good agreement with coupled channel calculations are obtained. The sensitivity of the spin alignment to reaction models is discussed. 相似文献
9.
Paul A. E. Piunno James Watterson Christopher C. Wust Ulrich J. Krull 《Analytica chimica acta》1999,400(1-3):73-89
Immobilized single-stranded DNA (ssDNA) can be used as a selective ‘reagent’ to bind complementary DNA or RNA for applications such as the detection of pathogenic organisms, gene therapy agents and genetic mutations. The density of ssDNA on a surface will determine the charge density due to ionizable phosphate groups. Such a negatively charged interface will attract positive counter-ions from solution, which may result in a local ionic strength, pH and dielectric constant on the surface that is substantially different from that in bulk electrolyte solution. It is the local conditions which influence the thermodynamics of hybridization, and this can studied by the melt temperature (Tm) of double-stranded DNA (dsDNA). Experimental work and theoretical models have been used to examine whether hybridization reactions on a surface can cause dynamic changes in local charge density, and therefore, changes in selectivity and drift in calibration for quantitative analysis. Organosilane chemistry has been used to covalently immobilize hexaethylene glycol linkers and to control the subsequent density of dT20 that was prepared by automated synthesis. Fiber-optic biosensors based on fused silica that was coated with DNA were used in a total internal reflection fluorescence instrument to determine Tm from the dissociation of duplexes of fluorescein-labeled dA20 : dT20. The experimental results suggest that the thermodynamic stability of duplexes that are immobilized on a surface is dependent on the density of immobilized DNA and on the extent of hybridization of DNA. The experimental results show that the thermodynamic stability of immobilized dsDNA is significantly different than that of dsDNA in bulk solution, and include observations of the variation of enthalpy at different ionic strengths, asymmetry in the melt curves, and the possibility of a reduced dielectric constant within a DNA layer relative to that in bulk solution. 相似文献
10.
H. G. Bohlen H. Ossenbrink W. von Oertzen P. Wust H. Hafner K. Wannebo 《Zeitschrift für Physik A Hadrons and Nuclei》1978,285(4):379-388
Measuring energy spectra of nuclei afterγ-decay of excited states in flight the spin alignment of12C2+ states has been measured. Inelastic scattering,16O(16C,12C2+)16O and the reaction12C(16O,12C2+)16O leading to12C2+ (4.43 MeV) state have been studied. Characteristic line shapes of the12C2+ peak were observed using a Q3D magnetic spectrometer. The magnetic substate (m-states) population has been deduced from the spectra as function of reaction angle. A comparison of the measuredm-state population with reaction models shows that the first reaction is consistent with inelastic scattering although discrepancies remain. Discrepancies are also obtained if the reaction12C(16O,12C2+)16O is interpreted using a FRDWBA transfer calculation. At least 1/3 of the cross section can be attributed toα-transfer. A calculation which couples transfer and inelastic scattering channels seems to be necessary. 相似文献