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Selected papers from the latest issue:Microfluidics for the deposition of density gradients of immobilized oligonucleotide probes; developing surfaces that offer spatial control of the stringency of DNA hybridization (Highlighted Copy)
09 October 2011, 22:23:57
Publication year: 2011
Source: Analytica Chimica Acta, Available online 8 October 2011
M. Omair Noor, Ulrich J. Krull
A method for the development of continuous density gradients of immobilized oligonucleotide probes (20mer) along the length of microfluidic channels is demonstrated. The development of continuous density gradients was achieved using variable electrokinetic transport of probes in hybrid glass-polydimethylsiloxane microfluidic chips. The probes were terminated with an amine functional group, and were delivered by electrokinetic pumping to the flat glass channel wall after it had been densely coated with covalently immobilized aldehyde groups. This method provided probe immobilization densities ranging from 4.5(±0.8) ×10to 2.5(±0.8) ×10molecules/cm, with longitudinal dilution and differential mass transport of the injected plug of probes being the primary factors responsible for the gradient of density. The utility of the resulting density gradient of immobilized probes to control the selectivity of hybridization was demonstrated at room temperature by discrimination between a fully complementary oligonucleotide target, and a target strand containing 3 base pair mismatches (3 BPM) based on the spatial pattern of hybridization for sub-picomole quantities of targets. Single nucleotide polymorphism (SNP) discrimination was possible when temperature control was implemented to improve resolution of the mismatch discrimination, allowing SNP discrimination at 35 °C with a contrast ratio of almost 5 to 1.
Source: Analytica Chimica Acta, Available online 8 October 2011
M. Omair Noor, Ulrich J. Krull
A method for the development of continuous density gradients of immobilized oligonucleotide probes (20mer) along the length of microfluidic channels is demonstrated. The development of continuous density gradients was achieved using variable electrokinetic transport of probes in hybrid glass-polydimethylsiloxane microfluidic chips. The probes were terminated with an amine functional group, and were delivered by electrokinetic pumping to the flat glass channel wall after it had been densely coated with covalently immobilized aldehyde groups. This method provided probe immobilization densities ranging from 4.5(±0.8) ×10to 2.5(±0.8) ×10molecules/cm, with longitudinal dilution and differential mass transport of the injected plug of probes being the primary factors responsible for the gradient of density. The utility of the resulting density gradient of immobilized probes to control the selectivity of hybridization was demonstrated at room temperature by discrimination between a fully complementary oligonucleotide target, and a target strand containing 3 base pair mismatches (3 BPM) based on the spatial pattern of hybridization for sub-picomole quantities of targets. Single nucleotide polymorphism (SNP) discrimination was possible when temperature control was implemented to improve resolution of the mismatch discrimination, allowing SNP discrimination at 35 °C with a contrast ratio of almost 5 to 1.
Highlights
► Mass transport reaction kinetics generate a density gradient of immobilized probes ► Targets with similar sequence identified by spatial pattern of hybridization ► Interactions of probes with surface ameliorated by temperature or use of formamideSensitivity evaluation of rhodamine B hydrazide towards nitric oxide and its application for macrophage cells imaging
09 October 2011, 22:23:57
Publication year: 2011
Source: Analytica Chimica Acta, Available online 8 October 2011
Chi-Ming Wu, Yen-Hao Chen, Kasala Dayananda, Tsun-Wei Shiue, Chen-Hsiung Hung, ...
A colorless and non-fluorescent rhodamine derivative, rhodamine B hydrazide (RH), is applied to detect nitric oxide and form fluorescent rhodamine B (RB). The reaction mechanism of RH with NO is proposed in this study. The probe shows good stability over a broad pH range (pH > 4). Furthermore, fluorescence intensity of RH displays an excellent linearity to the NO concentration and the detection limit is as low as 20 nM. A 1000-fold fluorescence turn-on from a dark background was observed. Moreover, the selectivity study indicated that the fluorescence intensity increasing in the presence of NO was significantly higher than those of other reactive oxygen/nitrogen species. In exogenously generated NO detection study, clear intracellular red fluorescence was observed in the presence of S-nitroso-N-acetyl-D,L-penicillamine (SNAP, a kind of NO releasing agent). In endogenously generated NO detection study, increasing incubation time of RH with lipopolysaccharied (LPS) pre-treated cells could obtain a highly fluorescent cell image. These cell imaging results demonstrated that RH can efficiently penetrate into Raw 264.7 cells and be used for detection of exogenously and endogenously generated nitric oxide.
Source: Analytica Chimica Acta, Available online 8 October 2011
Chi-Ming Wu, Yen-Hao Chen, Kasala Dayananda, Tsun-Wei Shiue, Chen-Hsiung Hung, ...
A colorless and non-fluorescent rhodamine derivative, rhodamine B hydrazide (RH), is applied to detect nitric oxide and form fluorescent rhodamine B (RB). The reaction mechanism of RH with NO is proposed in this study. The probe shows good stability over a broad pH range (pH > 4). Furthermore, fluorescence intensity of RH displays an excellent linearity to the NO concentration and the detection limit is as low as 20 nM. A 1000-fold fluorescence turn-on from a dark background was observed. Moreover, the selectivity study indicated that the fluorescence intensity increasing in the presence of NO was significantly higher than those of other reactive oxygen/nitrogen species. In exogenously generated NO detection study, clear intracellular red fluorescence was observed in the presence of S-nitroso-N-acetyl-D,L-penicillamine (SNAP, a kind of NO releasing agent). In endogenously generated NO detection study, increasing incubation time of RH with lipopolysaccharied (LPS) pre-treated cells could obtain a highly fluorescent cell image. These cell imaging results demonstrated that RH can efficiently penetrate into Raw 264.7 cells and be used for detection of exogenously and endogenously generated nitric oxide.
Highlights
► RH shows good stability over a broad pH range ► RH possesses excellent linearity between fluorescence intensity and NO concentration ► RH shows ca. 1000-fold fluorescence enhancement after reacting with 5 equiv. NO ► RH can be used to detect exogenous NO and to trace endogenous NO.A colorimetric probe for online analysis of sulfide based on the red shifts of longitudinal surface plasmon resonance absorption resulting from the stripping of gold nanorods
09 October 2011, 22:23:57
Publication year: 2011
Source: Analytica Chimica Acta, Available online 8 October 2011
Jia-Ming Liu, Fei-Ming Li, Li-Ping Lin, Xin-Xing Wang, Wen-Liang Cai, ...
A gold nanorods (GNRs) nonaggregation-based colorimetric probe has been developed for the detection of Sbased on that the longitudinal surface plasmon resonance absorption wavelength (LPAW) of GNRs red shifts (Δλ) and the color of the solution distinctly changes on account of the faster stripping of GNRs along longitudinal axis than transverse axis in the process of GNRs reacting with Sions to form Au2S complexes on the GNRs surfaces. The GNRs probe exhibits highly sensitive and selective response toward Swith a wide linear range from 10.0 to 10000.0 μM. The proposed colorimetric probe can be used to visibly detect Sin water samples on line in fifteen minutes with the results agreeing well with those of the optical sensor, showing its great practicality. Moreover, the detection mechanism of the probe is also discussed.
Source: Analytica Chimica Acta, Available online 8 October 2011
Jia-Ming Liu, Fei-Ming Li, Li-Ping Lin, Xin-Xing Wang, Wen-Liang Cai, ...
A gold nanorods (GNRs) nonaggregation-based colorimetric probe has been developed for the detection of Sbased on that the longitudinal surface plasmon resonance absorption wavelength (LPAW) of GNRs red shifts (Δλ) and the color of the solution distinctly changes on account of the faster stripping of GNRs along longitudinal axis than transverse axis in the process of GNRs reacting with Sions to form Au2S complexes on the GNRs surfaces. The GNRs probe exhibits highly sensitive and selective response toward Swith a wide linear range from 10.0 to 10000.0 μM. The proposed colorimetric probe can be used to visibly detect Sin water samples on line in fifteen minutes with the results agreeing well with those of the optical sensor, showing its great practicality. Moreover, the detection mechanism of the probe is also discussed.
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